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10 April 2014 Comprehensive Database on Induan (Lower Triassic) to Sinemurian (Lower Jurassic) Marine Bivalve Genera and Their Paleobiogeographic Record
Sonia Ros-Franch, Ana Márquez-Aliaga, Susana E. Damborenea
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Abstract

Marine bivalve genera that were described or mentioned for Triassic and Lower Jurassic deposits worldwide are reviewed in terms of their validity, stratigraphic range, paleogeographic distribution, paleoautecology, and shell mineralogy. Data were originally compiled at species level and are arranged systematically. A brief discussion for each genus includes synonymy, taxonomic status, and included subgenera, as well as current uncertainties about their validity and range. The distribution of each genus is also shown on paleogeographic maps. Type species and first and last appearances of each genus are also mentioned. We recognize as valid 281 genera and their included subgenera, and we further discuss 148 genera (arranged alphabetically) that were mentioned for the study interval but are not included for different reasons. The purpose of this paper is to provide an updated critical assessment of all available basic information for each genus, in order to obtain a sound database to study the generic paleodiversity of marine bivalves in the time interval from the Induan (Early Triassic) to the Sinemurian (Early Jurassic). This was a critical time for bivalve evolution and diversification, which began with the recovery from the Permian—Triassic extinction and ended with the recovery from the Triassic—Jurassic extinction.

INTRODUCTION

In order to study the generic paleodiversity of marine bivalves in the time interval from Induan (Early Triassic) to Sinemurian (Early Jurassic) (In-Sin), which begins with the recovery from the Permian—Triassic extinction and ends with the recovery from the Triassic-Jurassic extinction, a significant critical review of each genus was badly needed. The purpose of this paper is not merely to offer such a compendium of data extracted from the published literature, but to provide an updated critical assessment of all available information for each genus as well.

This paper is thus a review of all marine bivalve genera that were described for Triassic and Lower Jurassic deposits worldwide, in terms of their validity, stratigraphic range, paleogeographic distribution, paleoautecology, and shell mineralogy. We include marine bivalves only, and thus the families Pachycardiidae, Unionidae, and Neomiodontidae are not considered. Data were compiled at species level, with the purpose being to contrast the assignment of each species to the genera. Only published monographs and papers that include images and descriptions of the taxa were considered. This paper is a revised version of part of a Ph.D. thesis (Ros, 2009).

Methodology

We based our study mostly on bibliographic data, but the different records attributed to each genus were revised, checked, and critically updated as far as possible from systematic, stratigraphic, and geographic points of view.

First, we looked for all genera described in our study interval. The Treatise on Invertebrate Paleontology (Cox & others, 1969; Stenzel, 1971) was taken as reference for the period previous to 1965, accepting in most cases the proposed synonyms, although in some genera, subsequent literature that changed the Treatise views was also taken into account. However, we frequently used literature prior to the Treatise to try to elucidate some pending questions. For the time span between 1965 and the present, an exhaustive literature search was performed. To carry out this task, we referred to Zoological Record from 1965 to 2005 and other sources (Diener, 1923; Kutassy, 1931; Neave, 1939; Cox & others, 1969; Sepkoski, 2002; and several electronic sources, such as Paleobiology Database [PBDB] and Nomenclator Zoologicus).

Then we compiled all references into a bibliography about these genera and reviewed it. Since the amount of literature and data discussed here is quite large, we first proceeded to develop a bibliographic database that allowed us to handle them rapidly and effectively. This database was made using the computer program FileMaker Pro 8.5. The selection of this program was based on the simplicity of its construction, handling, and relation of information. The introduction of the species with author and year in the database is very important, instead of compiling the genera directly, since it allows us to control the different scope given to them over time. For example, the species decidens Bittner, 1899, was described in the genus Pseudomonotis, assigned later to Streblochondria and Claraia, in the end to be assigned by Newell and Boyd (1995) to Crittendenia and also as type species of Claraia (Bittnericlaraia) by Gavrilova (1996). If we had not introduced the species in the database, it would have been impossible to continue the history of this species, and we would have had the occurence of the same species in four different genera.

Through a careful revision of the literature, we eliminated all genera that, for one reason or other, should not be considered, including those with only doubtful occurrence in our study interval. These are treated in the section Genera not Included (see p. 156), listed alphabetically, with a brief explanation of the reason for their exclusion. Specifically, we do not include; (1) genera convincingly placed in synonymy; (2) subgenera for which we did not find any publication elevating them to genus level; (3) genera with no solid presence during the temporal study range, although they could have been mentioned for the study range; and (4) generic homonyms. Finally, there are some taxa that were listed in the Compendium of Fossil Marine Genera published by Sepkoski (2002), but which were not included in this analysis because they are regarded as subgenera.

Taxonomic data were reviewed as far as possible in order to assign all species to genera. We compared the generic diagnosis with the species descriptions and figures offered in the literature, and, in some instances, we consulted different specialists. We are aware that, even considering these meticulous analyses, it is impossible to eliminate all mistakes, and taxonomic decisions are always subjective, so the opinion of different authors is frequently indicated in the genus discussion. For the assignment of genera to different families, we followed Cox and others (1969) for genera described earlier than the Treatise, but more recent bibliographies that proposed changes in assignation are discussed and listed for each case. For genera described after 1965, we follow critically the assignment published in the literature. The survey includes only papers published before 2011.

Data Organization

Stratigraphic Ranges.—We follow the stratigraphic chart of Gradstein and Ogg (2004), using their stage names, except for the Permian, which is subdivided into three epochs: Cisuralian, Guadalupian, and Lopingian, here listed as early, middle, and late Permian, respectively.

For the equivalence between the different charts used in the reviewed bibliography, we used the conversion tables provided by the Paleobiology Database ( http://www.paleodb.org/) and Geo When Database ( http://www.stratigraphy.org/geowhen/index.html).

We had some problems distinguishing between Rhaetian and Norian in papers older than the redefinition of Rhaetian by Dagys and Dagys (1994). At least the Kössen Formation in Austria and the Gabbs Formation in the United States can be regarded as Rhaetian in age (Dagys & Dagys, 1994; Hallam, 2002).

We used H. J. Campbell and Raine (in Cooper, 2004) and H. J. Campbell, Raine, and Wilson (in Cooper, 2004) for the correlation of New Zealand stages with the Global Geochronological Scale.

For each genus, we indicate the entire stratigraphic range observed after reviewing the literature, and the two records we regard as the first and last appearances. Stratigraphic ranges are compared with those in Cox and others (1969), which is the most recent published review with a thorough taxonomic revision and stratigraphic data. In most cases, those ranges are changed with the new information here considered. We also compared our data with Sepkoski's (2002) compilation.

It should be pointed out that the stratigraphic ranges offered are observed, i.e., the first and last occurrences of a taxon are the limits of its stratigraphic range, which is only an approximation to the real range, and therefore also to the moment of origination and extinction. The effects of sampling, stratigraphic hiatuses, transgressions and regressions, Signor-Lipps effect, and other factors may greatly influence or distort the actual ranges (Holland, 1995). We must also bear in mind that the distribution of fossil bivalves is particularly dependent on facies.

Paleogeographic distribution.—For each genus, we provide the paleogeographic distribution during the time interval considered in this review. For those genera present in the Paleozoic, the paleogeographic distribution during the late Permian is also given. This section is not intended as a paleobiogeographic study, although the domains considered were established both in a paleogeographic and a paleobiogeographic sense (Westermann, 2000). We merely review the distribution of each genus and represent it on paleogeographic maps. Consequently, the term domain as used here has no paleobiogeographic implication.

The distribution of each genus in space and time is shown in three maps, for Permian—Triassic, Middle Triassic, and Triassic—Jurassic intervals. These representations sketch the position of continents at the three time moments selected, but they are not strictly faithful to all recent knowledge in every detail. The maps are based on and adapted from various sources. The first map was compiled mainly following Ziegler, Huiver, and Rowley (1997) and Christopher Scotese's maps available on his website Paleomap Project ( http://www.scotese.com) ; the following two maps were based on Golonka and Ford (2000) and Golonka (2004, 2007). We introduced some changes, especially in the configuration of Cimmerian block, Lhasa block, and southern part of the Tethys following Dèzes (1999), Nicoll (2002), J. Yin and Grant-Mackie (2005), and J. Yin and McRoberts (2006).

The paleogeographic distribution for each genus was recorded by using contemporary country names, which were then grouped into the following paleogeographic informal domains: Tethys, Circumpacific, Boreal, and Austral. As here understood, the Tethys domain covers the entire length of the Tethys Sea during the time interval here considered, without differentiating between Neotethys and Paleotethys. The Boreal domain includes mainly the northern part of Russia, Greenland, northern Canada, and Alaska. The Austral domain comprises the southern part of South America (part of Argentina and Chile), New Zealand, New Guinea, and Antarctica. Finally, the Circumpacific domain covers the Paleopacific, being limited to the north and south by the Boreal and Austral domains, respectively. For the location of countries in the different domains, we mostly follow Nakazawa (1991), Dercourt, Ricou, and Vrielynck (1993), Metcalfe (1998, 1999), Gaetani and others (2000a, 2000b, 2000c), Acharyya (2000), Stampfli and others (2001), Stampfli and Borel (2002, 2004), Chumakov and Zharkov (2003), and Klets (2005), in addition to those cited above for construction of the maps. Every genus, even those with localized occurrences, was referred to one or more of these domains.

Although we indicate the distribution of each genus only during the time interval considered in this review, in some cases, we also discuss their paleogeographic range before or after this interval, if we find this relevant for any reason. The distribution of each genus is listed according to the domains just mentioned, and each indicates the countries in which the genus was found with the relevant bibliographic data sources. If a distribution for a genus in the literature is uncertain, we use a question mark (?) herein for that record. We occasionally discuss data included in papers with no illustrations of the specimens, but these records were not taken into account for the distribution of genera. These are mostly related to Russia and China, especially to some pre-1980 literature that we could not see for this study.

Paleoautecology.—The modes of life of the genera included are assigned according to the original bibliographic source, and, when this was not possible, they were inferred by functional morphology or analogy with related Recent species. The categories recognized here are based mainly on S. M. Stanley (1968, 1969, 1970, 1972), Kauffman (1969), Bambach (1977, 1983), Bambach, Bush, and Erwin (2007), and others. We are aware that there are many exceptions to the general guidelines given for the recognition of modes of life, so they will necessarily be tentative and always referred to adult specimens (the different modes of life that a bivalve can display along its ontogeny were not taken into account). Sometimes it was not possible to assign a unique mode of life to one genus, because the included species may differ in this aspect. When there was not enough information about the genus morphology or about the environment in which it is recorded, we refer to the predominant mode of life within the family.

The following aspects were taken into account for establishing the different modes of life: life position in relation to water column and substrate, trophic group, mobility, and fixation. The mode of life assigned to each genus is coded by letters, as follows:

Position on the water column: benthic [B] or pseudoplanktonic [Ps].

Trophic group: suspensivorous [S] and detritivoraus [D]. Carnivorous bivalves are mostly beyond our study interval, because septibranchs appeared in the Jurassic (later than Sinemurian). In addition, we indicate possible photosymbiotic [Ph] and chemosymbiotic [Ch] relationships with microorganisms.

Life position in relation to the substrate: epifaunal [E], shallow infaunal [Is], deep infaunal [Id] or semi-infaunal [Se].

Mobility, sedentary [Sed], facultative mobile [FaM], slow mobile [SM], and fast mobile [FM], Regarding mobility, SM and FM are categories only considered for burrower bivalves, while FaM refers to swimmer and pseudoplanktonic bivalves.

Fixation: we consider if they lived attached to the substrate or unattached [Un]; attached bivalves can be byssate (endobyssate [Endo] or epibyssate [Epi]) or cemented [C].

Several modes of life are then defined by the intersection of the categories just mentioned: shallow burrower in soft substrate [Sb], deep burrower [Db], borer [Bo], byssate [By], cemented [C], recliner [R], swimmer [Sw], nestler [N].

Mineralogy.—Shell mineralogy data provided here are taken mostly from J. D. Taylor, Kennedy, and Hall (1969, 1973), Carter (1990a, 1990b, 1990c), Carter, Lawrence, and Sanders (1990), and Carter, Barrera, and Tevesz (1998). In specific cases, we used other sources that are indicated in the discussion of each genus.

Mineralogy of shell layers is given for each genus, when this information is available; alternatively, we assign the predominant mineralogy for the family. Three types of mineralogy are considered: aragonitic, when all shell layers are fully formed by aragonite; bimineralic: when at least one of the shell layers is calcitic and the others ar agoni tic; and calcitic, when all shell layers are formed by calcite.

INCLUDED GENERA

The systematic arrangement used here follows Amler (1999), Amler, Fischer, and Rogalla (2000), and Bouchet and Rocroi (2010) with some modifications. Those are the most complete general Bivalve mollusk classifications that include fossil families introduced after the Treatise on Invertebrate Paleontology. The changes introduced here are: Lipodonta is recognized as a subclass following Cope (1995) and including the Solemyoidea; family Pichleriidae is included with the Limopsoidea; superfamilies Dimyoidea and Plicatuloidea are included within the Ostreida rather than the Pectinida; the name Terquemiidae Cox, 1964, is replaced by Prospondylidae Ptchelincev, 1960 (Hautmann 2001a), the classification of the superfamily Kalenteroidea Marwick, 1953, has been emended, according to Z. Fang and Morris (1997) and Damborenea (2004).

The genera included in this review are listed in systematic order below (Table 1). Each of them is then briefly discussed separately, with indication of type species, possible synonym names, and details of stratigraphic and paleogeographic distribution, mode of life, and shell structure.

Table 1.

Summary of various data for included genera, arranged in the order in which they are discussed herein. Abbreviations: (1) Stratigraphic range: O, Ordovician; Tre, Tremadocian; Dev, Devonian; Llan, Llanvirnian; Fam, Famennian; Car, Carboniferous; Miss, Mississippian; Vis, Visean; Penn, Pennsylvanian; Pe, Permian; Sak, Sakmarian; Art, Artinskian; Guad, Guadalupian; Wuch, Wuchiapingian; Chang Changhsingian; Tr, Triassic; In, Induan; Ol, Olenekian; Ani, Anisian; Lad, Ladinian; Car, Carnian; Nor, Norian; Rha, Rhaetian; J, Jurassic; Hett, Hettangian; Sin, Sinemurian; Plie, Pliensbachian; Toa, Toarcian; Aal, Aalenian; Baj, Bajocian; Call, Callovian; Oxf, Oxfordian; Kim, Kimmeridgian; Tit, Tithonian, Cret, Cretaceous; Berr, Berriasian; Val, Valanginian; Haut, Hauterivian; Apt, Aptian; Alb, Albian; Cen, Cenomanian; Tur, Turanian; Cam, Campanian; Maa, Maastrichtian; P, Paleocene; Dan, Danian; L., Lower; M., Middle; U., Upper; (2) Paleoautoecology: B; benthic, Ps, pseudoplanktonic, D, detritivorous, S, suspensivorous, Ph, photo-symbiotic; Ch, chemosymbiotic, E, epifaunal, Is, shallow infaunal, Id, deep infaunal, SI, semi-infaunal, FM, fast mobile, SM, slow mobile, FaM, facultative mobile, Sed, sedentary, Un, unattached, Endo, endobyssate, Epi, epibyssate, C, cemented, Sb, burrower in soft substrate, Db, deep burrower, Bo, borer, By, byssate, R, recliner, Sw, swimmer, N, nestler.

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Figure 1.

Paleogeographical distribution of Nuculidae (Palaeonucula, Trigonucula, Nuculoma). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

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Superfamily NUCULOIDEA Gray, 1824
Family NUCULIDAE Gray, 1824
Genus PALAEONUCULA Quenstedt, 1930, p. 110

  • Type species.—Nucula hammeri Defrance, 1825b, p. 217.

  • Remarks.—Palaeonucula was regarded as subgenus of Nuculoma, Nucula, and Nuculopsis (see Hodges, 2000, p. 13) and even as a synonym of the last (Nakazawa & Newell, 1968); it is here regarded as a valid genus, following Carter (1990a) and Hodges (2000).

  • Stratigraphic range.—Middle Triassic (lower Anisian)—Lower Cretaceous (Aptian) (Komatsu, Chen, & others, 2004; Gang, 2001). The stratigraphic range was here extended, both with respect to the Triassic—Jurassic range in Cox and others (1969), and also to Sepkoski (2002), who assigned a Triassic (Ladinian)—Jurassic (Tithonian) age. The oldest records we accept are Anisian (Tamura & others, 1975; Wen & others, 1976; Komatsu, Chen, & others, 2004). Although Bailey (1978) mentioned the species Palaeonucula strigilata from the Mississippian of Arkansas, this will not be taken into account because the source is an abstract in a conference proceedings volume, and we did not find any reference where the author figured or described the species. The genus was widely mentioned throughout the interval Middle to Late Jurassic (Pugaczewska, 1986; Sha & Fürsich, 1994; Holzapfel, 1998; Harries & Little, 1999; Gahr, 2002; Delvene, 2003; J. Yin & Grant-Mackie, 2005).

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 1).

  • Tethys domain; Middle Triassic; northern Vietnam (Komatsu, Huyen, & Huu, 2010); Anisian of China (Wen & others, 1976; Komatsu, Chen, & others, 2004), Spain (Márquez-Aliaga, 1985), Malaysia (Tamura & others, 1975); Ladinian of Germany (Ürlichs, 1992), Spain (Márquez-Aliaga, 1985; Niemeyer, 2002), Malaysia (Tamura & others, 1975); Late Triassic; of China (Gou, 1993); Carnian of China (Wen & others, 1976), Italy (Fürsich & Wendt, 1977), Malaysia (Tamura & others, 1975); Norian of China (Lu, 1981), Iran (Repin, 2001; Hautmann, 2001b); Rhaetian of Iran (Hautmann, 2001b), Hungary (Vörös, 1981); Early Jurassic: Hettangian—Sinemurian of England (Liu, 1995; Hodges, 2000); Sinemurian of Turkey (M. A. Conti & Monari, 1991); Sinemurian of southwestern France, Spain, & Portugal (Liu, 1995).

  • Circumpacific domain; Middle Triassic; Anisian of Chile (Barthel, 1958); Late Triassic; Carnian of Japan (Hayami, 1975); Early Jurassic: Hettangian—Sinemurian of Chile (Aberhan, 1994a; Damborenea, 1996a); Sinemurian of Canada (Aberhan, 1998a).

  • Boreal domain; Late Triassic; northeastern Siberia (Yakutia Region) (Kurushin, 1987); Triassic—Jurassic; northeastern Asia (Kurushin, 1990).

  • Paleoautoecology.—B, D, Is, FM; Sb. Holocene nuculids dig into the surface layers of the sediment and remain very close to its surface. They actively use the foot to dig and move around and use the palp proboscis to feed on detritus (Reid, 1998). A similar mode of life is suggested for Palaeonucula. Its external form would facilitate a fairly quick movement through the sediment. Pallial sinus is not observed, and thus it probably did not have siphons. Living nuculids are commonly found in shallow waters and fine-grained sandy sediments, and this is consistent with the associated lithology of fossil species (Hodges, 2000). All previous authors considered Palaeonucula as an infaunal, mobile, and shallow burrowing detritivorous bivalve (see e.g., Pugaczewska, 1986; Damborenea, 1987a; M. A. Conti & Monari, 1991; Holzapfel, 1998; Delvene, 2003).

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 150). Outer shell layer: aragonite (irregular prismatic). Middle and inner shell layers; aragonite (homogeneous).

  • Genus TRIGONUCULA Ichikawa, 1949, p. 267

  • Type species.—Trigonucula sakawana Ichikawa, 1949, p. 268.

  • Stratigraphic range.—Upper Triassic (Carnian—upper Rhaetian) (Hayami, 1975; Hautmann, 2001b). Both Cox and others (1969) and Sepkoski (2002) assigned a Upper Triassic range to this genus. This is here maintained, despite references from the Jurassic and Cretaceous: Trigonucula yunshanensis Yu & Li (in Z. Li & Yu, 1982, p. 94, fig. 13–14) and Trigonucula? yunshanensis (Gu, Li, & Yu, 1997, p. 15, pl. 2,8–9). Nevertheless, both the hinge and shell outline of these species are totally different from those described for Trigonucula sakawana and therefore probably do not belong to the genus (Jingeng Sha, personal communication, 2008). Dickins and McTavish (1963) mention the genus (Trigonucula sp.) in the Lower Triassic (Scythian), but this will not be taken into account for two reasons; (1) it was not included in Cox and others (1969); and (2) the figures in Dickins and McTavish (1963) are impossible to compare due to their poor quality; also the authors pointed out in their discussion (p. 129): “In shape Trigonucula sp. is not unlike Nucula sp. juv. ind. Spath (1930, p. 53, pl. 12,12) from the Lower Triassic (Otoceratan) of Greenland.”

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 1).

  • Tethys domain; Late Triassic; Norian of Iran (Hautmann, Aghababalou, & Krystyn, 2011); Rhaetian of Iran (Hautmann, 2001b).

  • Circumpacific domain; Late Triassic; Carnian of Japan (Ichikawa, 1949; Hayami, 1975; Kobayashi & Tamura, 1983b).

  • Paleoautecology.—B, D, Is, FM; Sb. A relatively quick shallow burrower and detritivorous mode of life is attributed to this genus, similar to the living nuculids (Reid, 1998). Hautmann (2001b, p. 26) described divaricate ornamentation of the shell in his emended diagnosis of the genus. This type of ornamentation has been studied from a functional point of view by several authors (e.g., S. M. Stanley, 1969; Seilacher, 1972), and it is now known that it facilitates excavation (Checa & Jiménez-Jiménez, 2003b).

  • Mineralogy.—Aragonitic. No specific data about the Trigonucula mineralogy and shell microstructure is known, but a totally aragonitic mineralogy is assumed, according to the diagnosis of subclass Paleaeotaxodonta given by Allen and Hannah (1986).

  • Genus NUCULOMA
    Cossmann in Cossmann & Thièry, 1907, p. 124

  • Type species.—Nucula castor d'Orbigny, 1850, p. 339.

  • Stratigraphic range.—Upper Triassic (Rhaetian)—Lower Cretaceous (Valanginian) (Laws, 1982; Kaim, 2001). Although Nuculoma was regarded as a typical Jurassic genus (Cox & others, 1969; Sepkoski, 2002), it was found in the Rhaetian of New York Canyon (Laws, 1982; Guex & others, 2003, 2004; Lucas & Tanner, 2004; Lucas & others, 2007) and in the Lower Cretaceous of several localities (Kaim, 2001; Marinov & others, 2006; X. Li, 1990). Accordingly, its stratigraphic range is here extended.

  • Although originally used for Jurassic forms, several Recent species were also included in Nuculoma. There is no revision of these living species to test which ones are really consistent with the diagnosis, but they will not be taken into account here, because, according to Hansson (1998, p. 93), living species should be included in Ennucula Iredale, 1931 [“Ennucula Iredale, 1931 = Nuculoma: auct., non Cossmann in Cossman & Thièry, 1907 (Nucula castor d'Orbigny, 1850 - Jurassic fossil)”].

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 1). Available information suggests that the genus appeared in the Circumpacific domain, specifically in the Rhaetian of Nevada (Guex & others, 2004), and, during the Early Jurassic, it spread to the Tethys (Hallam, 1972, 1977) and Boreal domains (Zakharov & others, 2006). Later, during the Jurassic, its distribution expanded not only to the European Tethys (X. Li & Grant-Mackie, 1994; Holzapfel, 1998), but also to the Proto-Atlantic (Liu, 1995).

  • Circumpacific domain; Late Triassic; Rhaetian of Nevada (Hallam & Wignall, 2000); Early Jurassic; Hettangian of Nevada (Hallam & Wignall, 2000).

  • Tethys domain; Early Jurassic; Sinemurian of Europe (Hallam, 1977).

  • Paleoautoecology.—B, D, Is, FM; Sb. Fürsich (1982) compared Nuculoma with Recent Nucula, and he assigned it a similar mode of life, moving just below the sediment surface, feeding on the detritus taken with palp proboscis, like other nuculids.

  • Mineralogy.—Aragonitic (Carter, 1990b, p. 307). Outer shell layer: aragonite (prismatic). Middle and inner shell layers; aragonite (nacreous).

  • Superfamily NUCULANOIDEA
    Adams & Adams, 1858 in 1854–1858
    Family NUCULANIDAE Adams & Adams, 1858 in 1854–1858
    Genus NUCULANA Link, 1807, p. 155

  • Type species.—Arca rostrata Chemnitz, 1784, pl. 55, fig. 550–551.

  • Remarks.—Nuculana is a genus especially difficult to identify since the external characters alone, in absence of inner views, are undistinguishable from those of other genera, such as Phaenodesmia Bittner, 1894, Phestia Chernyshev, 1951, Veteranella (Veteranella) Patte, 1926, or V. (Glyptoleda) Fletcher, 1945; hence many Paleozoic and Mesozoic specimens attributed to Nuculana probably belong to other genera (Boyd & Newell, 1979; Damborenea, 1987a; Carter, 1990a; Z. Fang & Cope, 2004).

  • Leda Schumacher, 1817, is a junior objective synonym of Nuculana (both genera have the same type species). Although this was pointed out by Cox and others (1969), some authors still use the name Leda (e.g., Fürsich & Wendt, 1977; Ruban, 2006a).

  • Stratigraphic range.—Middle Triassic (Anisian)—Holocene (Tamura & others, 1975). Although there are references for this genus from the Paleozoic, we follow McAlester (in Cox & others, 1969), who considered its range to be from the Triassic to the present (see Nakazawa & Newell, 1968, p. 37–38 for discussion of this genus). Sepkoski (2002) extended it to the lower Induan, but the only mention from the Lower Triassic is Nuculana (Dacryomya) sp. from Japan in Nakazawa (1961); however, this was referred to as Phestia sp. by Nakazawa and Newell (1968). Therefore, the first appearance is regarded as Anisian (Tamura & others, 1975). Furthermore, the record is fairly continuous throughout the entire study interval (see Paleogeographic Distribution, below). However, not all authors agree about the presence of Nuculana in this time interval. Carter (1990a, p. 151) stated that Nuculana did not appear until the Cretaceous. In our opinion, a thorough review of this genus is needed, but it is beyond the scope of this paper, and we will tentatively use the proposed range.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 2). Although the genus is also present in the Early Jurassic from both the Circumpacific and the Austral domains, these records are Pliensbachian in age (Damborenea, 1987a; Aberhan, 1994a, 1998a).

  • Tethys domain; Middle Triassic: Anisian of Malaysia (Tamura & others, 1975), northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of Afghanistan (Farsan, 1975), Spain (Niemeyer, 2002), western Caucasus (Ruban, 2006a); Late Triassic: China (Cowper-Reed, 1927); Carnian of Italy (S. Conti, 1954), Slovenia (Jurkovsek, 1978), China (Wen & others, 1976; Lu, 1981; Gou, 1993; J. Yin, Enay, & Wan, 1999); Norian of Iran (Hautmann, 2001b; Repin, 2001); Norian—Rhaetian of England (Hallam & El Shaarawy, 1982; Hallam, 2002); Rhaetian of Italy (Sirna, 1968), Iran (Hautmann, 2001b; Repin, 2001), Spain (Márquez-Aliaga, Plasencia, & Ros, 2005), China (J. Yin, Enay, & Wan, 1999), Austria (Tomášových, 2006a, 2006b); Early Jurassic: Hettangian of China (J. Yin, Enay, & Wan, 1999); Hettangian—Sinemurian of England (Liu, 1995); Sinemurian of Turkey (M. A. Conti & Monari, 1991).

  • Circumpacific domain: Late Triassic: Carnian of Mexico (Alencaster de Cserna, 1961), Peru (Jaworski, 1922; Cox, 1949); Norian of Nevada (Laws, 1982).

  • Boreal domain: Middle Triassic: northern Siberia (Dagys & Kurushin, 1985), Primorie (Kiparisova, 1972); Late Triassic: Carnian of Primorie (Kiparisova, 1972); Triassic-Jurassic: northeastern Asia (Kurushin, 1990). Holocene species have a wide distribution in the boreal domain and in cold-temperate regions.

  • Austral domain: Late Triassic: Carnian of New Zealand (Marwick, 1953), Carnian—Norian of New Guinea (Skwarko, 1967); Rhaetian of New Zealand (Grant-Mackie, 1960).

  • Paleoautoecology.—B, D, Is, FM; Sb. Holocene species of this genus are very fast burrowers (Gordillo & Aitken, 2000), moving in the surface of the sediment, with a detritivorous trophic regime (Damborenea, 1987a; M. A. Conti & Monari, 1991; Holzapfel, 1998; Hautmann, 2001b).

  • Mineralogy.—Aragonitic (Carter, 1990b, p. 311–312, for Recent species). All shell layers: aragonite (homogeneous).

  • Figure 2.

    Paleogeographical distribution or Nuculanidae (Nuculana, Phestia, Veteranella, Eleganuculana, Xiaoschuiculana). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f02_01.jpg

    Genus PHESTIA Chernyshev, 1951, p. 9

  • Type species.—Leda inflatiformis Chernyshev, 1939, p. 116.

  • Remarks.—We regard Polidevcia Chernyshev, 1951, p. 25, as a subgenus of Phestia (see discusion for Polidevcia in Genera not Included, p. 168).

  • The generic name was first proposed in Chernyshev, 1943, p. 35, but no type species was designated, and it remained a nomen nudem until the type was designated by this author in 1951.

  • Stratigraphic range.—Middle Ordovician (lower Llanvirn)—Upper Triassic (Carnian) (Carter, 1990a; Z. Fang & Cope, 2004). Cox and others (1969) assigned this genus a Devonian—Lower Triassic range, and Sepkoski (2002), considered it was present from the Devonian (Givetian) to Lower Triassic (data taken from Skelton & Benton, 1993), but the range is extended in this paper. The first occurrence of the genus was Middle Ordovician (Llanvirnian [=overlaps with Darriwilian stage]), according to Z. Fang and Cope (2004), although doubtfully because the figured specimen is an external mold, and the internal features are unknown. Thus, although reference to Phestia seems justified, the same authors note that it externally resembles Glyptoleda (regarded in this paper as a subgenus of Veteranella). Carnian is used here as the upper limit, based on data provided by Carter (1990a, p. 153). This author considered that “Nuculana“sulcellata, from the Italian Carnian, would be better located within Phestia, since its form, ligament structure, and nacreous interior are typical of this genus. Nakazawa and Newell (1968) included Nuculana (Dacryomya) sp., figured by Nakazawa (1961, p. 270, pl. 14,5–7), in Phestia, and thus extended the range of this genus to the Triassic of southwestern Japan. Hautmann and others (2005) mentioned Phestia? cf. perlonga (Mansuy) from the upper Rhaetian of southern Tibet, but this is the type species of Mesoneilo Vu Khuc, 1977a, p. 676, to which the authors did not refer in their paper. This very doubtful record will not be taken into account here.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 2). Cox and others (1969) regarded Phestia as a cosmopolitan genus, but, although it was very widespread during the Paleozoic, during the studied time interval, it was only present in the Tethys, the Boreal, and the Circumpacific domains.

  • Tethys domain: late Permian: Iran (Teichert, Kummel, & Sweet, 1973), Tunisia and India (Boyd & Newell, 1979), southern China (L. Li, 1995; Clapham & Bottjer, 2007), Oman (Dickins, 1999); Late Triassic: Carnian of Italy (Carter, 1990a).

  • Circumpacific domain: late Permian: Japan (Nakazawa & Newell, 1968; Murata & Bando, 1975; Hayami & Kase, 1977); Early Triassic: Japan (Nakazawa & Newell, 1968).

  • Boreal domain: late Permian: northeastern Russia (Biakov, 1998, 2002, 2006, 2007; Klets & others, 2006).

  • Paleoautoecology.—B, D, Is, FM; Sb. Phestia most probably had a mode of life similar to the living Nuculana, but it lacked a pallial sinus, so it possibly did not have true siphons (as Nuculana has). Instead, it may have had pseudosiphons created by ciliary connections between the undulations of the mantle (see Bradshaw, 1999, p. 75–76). The genus was regarded as a superficial burrowing detritivore that used the palp proboscis to collect food particles (Hoare, Heaney, & Mapes, 1989; Bradshaw, 1999). R. Zhang and Yan (1993) agreed with this and provided a reconstruction of its mode of life, showing the similarity to Palaeoneilo. The elongated anterior part and the anterior pedal muscle scars, which can be observed in some specimens, suggest it had a large foot that would allow it to burrow effectively (Mángano & others, 1998). These authors associated the ichnofossil Lockeia ornata with Phestia, from which they concluded that Phestia was a vagrant detritivorous capable of moving subhorizontally in the sediment.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 154–155). Outer shell layer: aragonite (prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus VETERANELLA Patte, 1926, p. 158

  • Type species.—Nuculana (Veteranella) strenua Patte, 1926, p. 158.

  • Stratigraphic range.—lower Permian (Artinskian)—Upper Triassic (Norian) (Kutassy, 1931; Waterhouse, 1964). The stratigraphic range is here extended with respect to Sepkoski (2002), because we include Glyptoleda and Nucundata as subgenera of Veteranella, according to Cox and others (1969) (see discussion for Glyptoleda and Nucundata in Genera not Included, p. 161, 166).

  • Cox and others (1969) assigned a Permian—Triassic range to Veteranella; Sepkoski (2002) considered Nucundata to be present in the Permian following Cox and others (1969), Glyptoleda in the late Guadalupian following Waterhouse (1987), and a Norian range for Veteranella following Hallam (1981). J. Chen, Liu, and Lan (1983) mentioned Glyptoleda and other genera attributed to their new subfamily Veteranellinae from Devonian to Permian, but none of these genera was listed as being present before the Carboniferous (Z. Fang & Cope, 2004).

  • The oldest record of the genus (referred to Nucundata and Glyptoleda) is lower Permian (Artinskian—Kunguarian) of New Zealand (Waterhouse, 1964). The genus was also mentioned from Lower Jurassic age; e.g., Kurushin (1990) quoted Veteranella from the Triassic—Jurassic boundary, confirming its presence in lower Hettangian beds, and Zhakarov and others (2006) mentioned Glyptoleda from the Pliensbachian, but none of them justified the presence of this genus in the Lower Jurassic, because they neither figured the specimens nor included the original source of their data. The youngest record is Upper Triassic: Veteranella (Ledoides) Chen, Wen, & Lan in Wen & others, 1976, from Carnian—Norian of Tibet (Kobayashi & Tamura, 1983a), from Carnian of China (Wen & others, 1976), and from Norian of eastern Tethys (Hallam, 1981).

  • Paleogeographic distribution.—Tethys (Fig. 2). Veteranella had a wide distribution in Boreal and Austral domains during the early and middle Permian (Waterhouse, 1964, 1983; Biakov, 1998, 2006), but it was not found there during the late Permian.

  • Tethys domain: late Permian: Changhsingian of Nepal (Waterhouse & Chen, 2006); Late Triassic: China (Kutassy, 1931); Carnian of China (Wen & others, 1976); Carnian and Norian of southern Tibet (Kobayashi & Tamura, 1983a); Norian of Xizang (Tibet) (Z. Fang & others 2009).

  • Paleoautoecology.—B, D, Is, FM; Sb. Veteranella reidi (Fletcher, 1945) (Permian) is the oldest species with oblique chevron-type ornamentation, which became common among bivalves during the Cenozoic, and is interpreted as an adaptation to rapid escape from potential predators and for minimizing shell damage during burrowing (Checa & Jiménez-Jiménez, 2003a). Numerous studies demonstrated that this type of ornamentation facilitates excavation (S. M. Stanley, 1969, 1970; Seilacher, 1972), so this genus is regarded as a fast burrower.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998). Data provided for subclass Protobranchia. All shell layers: aragonite. Inner shell layer: usually nacreous.

  • Genus ELEGANUCULANA
    J. Chen & Yang, 1983, p. 355 [358]

  • Type species.—Eleganuculana nyeruensis J. Chen & Yang, 1983, p. 356.

  • Stratigraphic range.—Upper Triassic (Norian) (J. Chen & Yang, 1983). J. Chen and Yang (1983) described Eleganuculana including only the type species from Norian of Knagmar region in Xizang province (southern China). J. Chen, Liu, and Lan (1983) mentioned the same species from the Norian of Tibet.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 2).

  • Tethys domain: Late Triassic: Norian of southern China (J. Chen & Yang, 1983), Tibet (J. Chen, Liu, & Lan, 1983).

  • Paleoautoecology.—B, D, Is, FM; Sb. Similar to Nuculana.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998). No data are available for Eleganuculana. Protobranchia shell mineralogy is fully aragonitic (Carter, Barrera, & Tevesz, 1998).

  • Genus XIAOSHUICULANA J. Chen in J. Chen, Liu, & Lan, 1983, p. 622, 626

  • Type species.—Reticulana elegansa Li & Li in R. Zhang, Wang, & Zhou, 1977, p. 9.

  • Stratigraphic range.—Upper Triassic. Xiaoshuiculana was described by J. Chen (in J. Chen, Liu, & Lan, 1983) from Upper Triassic of China (Guangdong province), including only the type species. McRoberts (1997a) described a new species: X. tozeri McRoberts, 1997a, from the lower Rhaetian Antimonio Formation of Sonora (Mexico).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 2).

  • Tethys domain: Late Triassic: China (J. Chen, Liu, & Lan, 1983). Circumpacific domain: Late Triassic: Rhaetian of Mexico (McRoberts, 1997a).

  • Paleoautoecology.—B, D, Is, FM; Sb. Xiaoshuiculana is externally similar to Nuculana, but its rostrum is more elongated, and the shell bears oblique ribs (McRoberts, 1997a). These ribs would primarily strengthen the shell and probably also favored efficient excavation (Checa & Jiménez-Jiménez, 2003a).

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998). Data provided for subclass Protobranchia.

  • Family MALLETIIDAE Adams & Adams, 1858 in 1854–1858 Genus PHAENODESMIA Bittner, 1894, p. 188

  • Type species.—Phaenodesmia klipsteiniana Bittner, 1894, p. 188.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Rhaetian) (Hallam, 1981; F. Stiller, personal communication, 2008). Cox and others (1969) assigned a Triassic range in Europe to this genus. Sepkoski (2002), allegedly based on data provided by Hallam (1981), assigned it an Anisian—Norian range. However, Hallam (1981) considered that Phaenodesmia Was present in Carnian and Norian (including Rhaetian) deposits. The oldest record is from Anisian beds of the Alps (Diener, 1923) and southwestern China (F. Stiller, personal communication, 2008).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 3).

  • Tethys domain; Middle Triassic: Anisian of southwestern China (F. Stiller, personal communication, 2008), southern Alps (Diener, 1923); Late Triassic: Carnian of southern Alps (Diener, 1923).

  • Circumpacific domain; Late Triassic; South America (Hallam, 1981), Peru (Jaworski, 1922; Körner, 1937); Carnian of Chile (Nielsen, 2005).

  • Paleoautoecology.—B, D, Is, FM; Sb. We assign to this genus the same mode of life as other nuculids.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998). Data provided for subclass Protobranchia.

  • Figure 3.

    Paleogeographical distribution of Malletiidae (Phaenodesmia, Prosoleptus, Palaeoneilo, Lapteviella, Dianucula, Ningliconcha, Yongshengia). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f03_01.jpg

    Genus PROSOLEPTUS Beushausen, 1895, p. 95

  • Type species.—Nucula lineata Goldfuss, 1837 in 1833–1841, p. 153.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Fürsich & Wendt, 1977; Komatsu, Huyen, & Huu, 2010). Cox and others (1969) considered that Prosoleptus was present in the European Triassic. Sepkoski (2002) assigned it a Middle Triassic(?)—Carnian range following Hallam (1981), who mentioned Prosoleptus from Ladinian and Carnian deposits of western Tethys.

  • Fürsich and Wendt (1977) found P. lineata (Goldfuss, 1837 in 1833–1841) in the Cassian Formation of the southern Alps. This formation is regarded as upper Ladinian—Carnian in age, and probably for this reason, Hallam (1981) mentioned it from the Ladinian. Although Fürsich (in PBDB, 2005) confirmed that P. lineata occurs only in Carnian beds, it was recently reported from Anisian beds of northern Vietnam (Komatsu, Huyen, & Huu, 2010).

  • Paleogeographic distribution.—Tethys and ?Boreal (Fig. 3). Prosoleptus was present in the Tethys domain and probably also in northern Siberia (Carnian) (Kurushin, 1984).

  • Tethys domain; Middle Triassic; Anisian—Ladinian of northern Vietnam (Komatsu, Huyen, & Huu, 2010); Late Triassic; Carnian of Italy (south of the Alps) (Fürsich & Wendt, 1977), Germany (Goldfuss, 1863).

  • Paleoautoecology.—B, D, Is, FM; Sb. We assign the same mode of life as other nuculids.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 159–160; Carter, Lawrence, & Sanders, 1990, p. 315–316). All layers; aragonite (homogeneous).

  • Genus PALAEONEILO Hall & Whitfield, 1869, p. 6

  • The original spelling was Palaeaneilo Hall & Whitfield, 1869, p. 6, see McAlester, 1968, p. 41. For the authorship of the paper where this genus was named, see McAlester, 1968, p. 62.

  • Type species.—Nuculites constricta Conrad, 1842, p. 249.

  • Remarks.—There is some confusion in the literature among the genera Palaeoneilo, Praesaccella Cox, 1940, and Mesosaccella Chavan, 1947, p. 197 (see discussion in Damborenea, 1987a, p. 54). The problem stems from the fact that there are both Paleozoic and Mesozoic records of this genus and in the presence or absence of resilifer in different species referred to it. Some authors (cf. Damborenea, 1987a, p. 54; Aberhan, 1998a, p. 67) referred Paleozoic species to Palaeoneilo and Mesozoic species to Mesosaccella, but Cox (1937a) stated that there is no reason to separate the Paleozoic and Mesozoic species in different genera; this last criterion is followed here (but see Duff, 1978). Hodges (2000) regarded Palaeoneilo as a morphologically conservative genus that changed very little in general external shape through time.

  • Stratigraphic range.—Lower Ordovician (Tremadocian)—Lower Jurassic (Toarcian) (Gahr, 2002; Sánchez, 2002). Cox and others (1969) mentioned the range of this genus as Ordovician to the end of the Mesozoic, with a cosmopolitan distribution. Later, Sepkoski (2002) assigned it an Ordovician (upper Arenigian)—Jurassic (?upper Pliensbachian) range, following Pojeta (1971).

  • The first appearance is from the Lower Ordovician of Argentina (Sánchez, 2002). However, there are some problems with its last appearance. We accept Gahr's youngest record (2002) from the Toarcian; other younger records will not be taken into account, since almost all have some descriptive problems. For instance, Sha and Fürsich (1993) mentioned Palaeoneilo sp. from the Upper Jurassic and Lower Cretaceous of China, but they did not figure or systematically describe it. Later (Sha & Fürsich, 1994; Sha & others, 1998), they studied specimens from the same area and referred them to several species of Nuculana (Praesaccella) and Mesosaccella, but none to Palaeoneilo, although they discussed the problems of differentiating Palaeoneilo and Mesosaccella, and they even gave a series of guidelines to distinguish them. Hu, Jansa, and Wang (2008) also mentioned the genus from the Upper Jurassic—Lower Cretaceous interval, but not only did they not figure it, but they listed it as an ammonoid.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 3). Palaeoneilo was a cosmopolitan genus during part of Paleozoic and Mesozoic, at least during the study interval considered.

  • Tethys domain; late Permian; southern China (L. Li, 1995; Y. Wang & others, 2006; Y. Yin & others, 2006; He, Feng, & others, 2007); Early Triassic; China (Z. Yang & Yin, 1979; L. Li, 1995; Sha & Grant-Mackie, 1996); Middle Triassic; Tethys (Hallam, 1981); Muschelkalk and Buntsandstein of Poland (Senkowiczowa, 1985); Anisian of southern China (Komatsu, Chen, & others, 2004); Anisian—Norian of Malaysia and Thailand (Tamura & others, 1975); Ladinian of Afghanistan (Farsan, 1975); Late Triassic; Tethys (Hallam, 1981); Carnian of China (Sha & Grant-Mackie, 1996), southern Alps (Diener, 1923; Kutassy, 1931; Fürsich & Wendt, 1977); Carnian—Norian of China (Wen & others, 1976; Lu & Chen, 1986; Gou, 1993); Norian of southwestern China (Lu, 1981), Singapore (Kobayashi & Tamura, 1968a); Rhaetian of Burma (Diener, 1923); Early Jurassic; Hettangian—Sinemurian of southwestern England (Hodges, 2000); Sinemurian—Pliensbachian of Europe (Hallam, 1987).

  • Circumpacific domain; late Permian; Japan (Nakazawa & Newell, 1968; Hayami & Kase, 1977); Late Triassic; Mexico, Chile, and Peru (see references in Damborenea, 1987a); Carnian of Mexico (Diener, 1923), Japan (Hayami, 1975); Carnian—Norian of Japan (Onoue & Tanaka, 2005); Early Jurassic; Sinemurian of Chile (Covacevich, Pérez, & Escobar, 1991).

  • Boreal domain; late Permian; northeastern Russia (Biakov, 1998, 2007); Late Triassic; northeastern Russia (Polubotko & Repin, 1990).

  • Austral domain; Late Triassic; New Zealand (see references in Damborenea, 1987a), Rhaetian of New Zealand (MacFarlan, 1998) and Argentina (Damborenea & Manceñido, 2012); Early Jurassic; Pliensbachian of New Zealand (MacFarlan, 1998).

  • Paleoautoecology.—B, D, Is, FM; Sb. Palaeoneilo is regarded as a detritivorous bivalve, a superficial burrower living completely buried, very close to the sediment surface, like some living species of Yoldia (Damborenea, 1987a). It used a palp proboscis to feed on organic particles dispersed in the sediment (Hodges, 2000). Since in some species (e.g., P. elliptica) there is a shallow pallial sinus, presumably it had short siphons. Life position within the substrate most probably was with the posterior end up near the surface of the sediment, as interpreted for Phestia (see R. Zhang & Yan, 1993, p. 854, fig. 2). According to Hodges (2000), shell morphology indicates that Palaeoneilo was a quick burrower, and the foot could help to increase excavation speed.

  • Mineralogy.—Aragonitic (Carter & Tevesz, 1978; Carter, 1990a, p. 159–161; Carter, Lawrence, & Sanders, 1990, p. 315; Zhu & others, 1990). Outer shell layer: aragonite (homogeneous + fibrous prismatic). Middle and inner shell layers; aragonite (homogeneous).

  • Figure 4.

    Paleogeographical distribution of Yoldiidae (Rollieria) and Polidevciidae (Ryderia, Dacryomya). Late Triassic—Early Jurassic.

    f04_01.jpg

    Genus LAPTEVIELLA Kurushin in Dagys & Kurushin, 1985, p. 47

  • Type species.—Lapteviella prontchistshevi Kurushin in Dagys & Kurushin, 1985, p. 47.

  • Stratigraphic range.—Middle Triassic (Anisian) (Dagys & Kurushin, 1985). Lapteviella is a monospecific genus described by Kurushin (in Dagys & Kurushin, 1985) from the Anisian of northern Central Siberia. It is similar to Mesoneilo Vu Khuc, 1977a, but it differs by having a palliai sinus, prosogyrous beaks, and the anterior part of hinge shorter than the posterior. It is also comparable to Palaeoneilo (both have prosogyrous beaks, a similar arrangement of hinge teeth, shallow pallial sinus, concentric ornamentation, adductor muscle scars of similar shape, size, and position) (see fig. 6 and 10 in Dagys & Kurushin, 1985, and fig. 31 in Hodges, 2000). On the other hand, Lapteviella figures in Dagys and Kurushin (1985) show neither an internal septum nor the typical radial groove of Palaeoneilo.

  • Paleogeographic distribution.—Boreal (Fig. 3).

  • Boreal domain; Middle Triassic; Anisian of Siberia (Dagys & Kurushin, 1985; Klets, 2006) and northeastern Russia (Konstantinov, Sobolev, & Yadernkin, 2007).

  • Paleoautoecology.—B, D, Is, FM; Sb. Dagys and Kurushin (1985) indicated the presence of a smooth palliai sinus, from which the presence of short siphons could be inferred. We assign a mode of life similar to other members of the family Malletiidae, i.e., detritivorous, feeding from the substrate surface, and constantly moving to find new food sources.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998), data provided for the subclass Protobranchia.

  • Genus DIANUCULA Guo, 1988, p. 113

  • Type species.—Dianucula sulcata Guo, 1988, p. 113.

  • Remarks.—Guo (1988) included Dianucula in the family Malletiidae and we follow him, although Z. Fang and others (2009) included it in the family Afghanodesmatidae Scarlato & Starobogatov, 1979.

  • Stratigraphic range.—Upper Triassic (Norian) (Guo, 1988). Guo (1988) proposed Dianucula from upper Upper Triassic beds, and included two new species, the type and Dianucula ovata Guo, 1988. The genus was recorded from Dapingzhang formation, which is Norian in age (Feng & others, 2005). Sepkoski (2002) did not consider it in his compendium.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 3). Tethys domain: Late Triassic: Norian of southwestern China (Yunan province) (Guo, 1988).

  • Paleoautoecology.—B, D, Is, FM; Sb. We assign a mode of life similar to other members of the family Malletiidae, i.e., detritivorous, feeding from the substrate surface, and constantly moving to find new food sources.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998), data provided for subclass Protobranchia.

  • Genus NINGLICONCHA J. Chen & Stiller, 2008, p. 364

  • Type species.—Ningliconcha ningliensis J. Chen & Stiller, 2008, p. 365.

  • Stratigraphic range.—Upper Triassic (lower Norian) (J. Chen & Stiller, 2008). J. Chen and Stiller (2008) proposed the monospecific genus Ningliconcha and reported it from upper lower Norian of China (Yunnan province).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 3).

  • Tethys domain: Late Triassic: Norian of southwestern China (Yunnan province) (J. Chen & Stiller, 2008).

  • Paleoautoecology.—B, D, Is, FM; Sb. We assign this genus a mode of life similar to the rest of nuculids. The cancellate shell sculpture, characteristic of Ningliconcha (J. Chen & Stiller, 2008), probably aided in burrowing, as it does in other nuculids. The palliai line is integripalliate, and it either did not have siphons or they were short.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998), data provided for subclass Protobranchia.

  • Genus YONGSHENGIA J. Chen & Stiller, 2008, p. 360

  • Type species.—Palaeoneilo cuneata Chen in Ma & others, 1976, p. 195.

  • Stratigraphic range.—Upper Triassic (middle Norian) (J. Chen & Stiller, 2008). J. Chen and Stiller (2008) proposed Yongshengia based on P. cuneata Chen in Ma & others, 1976 (lower middle Norian of Yunnan) and tentatively included Palaeoneilo mundeni Fleming (in Fleming, Munden, & Suggate, 1954) from the Norian of New Zealand.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 3).

  • Tethys domain: Late Triassic: Norian of southwestern China (Yunan province) (Ma & others, 1976; Guo, 1985; Zhu & others, 1990; J. Chen & Stiller, 2008).

  • Austral domain: Late Triassic: Norian of New Zealand (Fleming, Munden, & Suggate, 1954).

  • Paleoautoecology.—B, D, Is, FM; Sb. Similar to Palaeoneilo. Yong-shengia is one of the largest nuculanoids and had a large posterior pedal muscle scar (J. Chen & Stiller, 2008). Its large size was probably inconvenient to fast burrowing, but this could be compensated for by a large foot (inferred by the pedal muscle scar).

  • Mineralogy.—Aragonitic. Zhu and others (1990) studied the shell microstructure of “Palaeoneilo“ cuneata, and they described a probable aragonitic outer shell layer of homogeneous microstructure and aragonitic inner layers.

  • Family YOLDIIDAE Dall, 1908b
    Genus ROLLIERIA Cossmann, 1920, p. 82

  • Type species.—Nucula palmae J. de C. Sowerby, 1824, p. 117.

  • Remarks.—Cox and others (1969) and other workers (Liu, 1995; Gahr, 2002) considered Rollieria as a subgenus of Nuculana Link, 1807, but here we regard it as a separate genus, following Hodges (2000, p. 36), who remarked that Rollieria lacks some of the characters of Nuculana: “... it does not possess the characteristic elongated posterior, lacks an escutcheon and is suboval in outline.” The name Rollieria also was used for an ammonoid genus, Rollieria Jeannet, 1951, p. 98, but Rollieria Cossman, 1920, has priority.

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Lower Cretaceous (Hodges, 2000; Jingeng Sha, personal communication, 2008). Cox and others (1969) assigned it a Jurassic range, as did Sepkoski (2002), based on data from Hallam (1977). The oldest record is Hettangian (Hallam, 1972, 1976, 1977, 1987, 1990; Hodges, 2000). Sowerby described the type species from sediments of Carboniferous age, but Hodges (2000, p. 35–36) doubted the presence of Rollieria at that time, based on the fact that the genus was never found again in sediments older than Jurassic.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 4). Tethys domain: Early Jurassic: Hettangian—Sinemurian of southwestern Britain (Hodges, 2000; Mander, Twitchett, & Benton, 2008; Hallam & Wignall, 2000), Europe (Hallam, 1976, 1977, 1987).

  • Circumpacific domain: Early Jurassic: South America (Damborenea, 2002b).

  • Paleoautoecology.—B, D, Is, FM; Sb. We assign a mode of life similar to other nuculanoids. General morphology of the species of this genus suggests that it was a quick burrower (Hodges, 2000). Rollieria had a shallow palliai sinus, and thus probably had short siphons. We assume that the Rollieria mode of life was similar to Palaeoneilo.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998), data provided for subclass Protobranchia.

  • Family POLIDEVCIIDAE Kumpera, Prantl, & Růžička, 1960
    Genus RYDERIA Wilton, 1830, p. 72

  • Type species.—Leda renevieri Oppel, 1856 in 1856—1858, p. 215.

  • Remarks.—Although several authors include Ryderia as a subgenus of Nuculana, it is considered here as an independent genus, following Cox and others (1969). However, we regard Teinonuculana Zhang in Zhang, Wang, & Zhou, 1977, p. 9, as a synonym of Ryderia (see discussion of Teinonuculana in Genera not Included, p. 171).

  • Stratigraphic range.—Upper Triassic (Rhaetian)—Lower Jurassic (Toarcian) (Liu, 1995; J. Yin & McRoberts, 2006). Cox and others (1969) indicated that this genus was present in Europe during the Jurassic. Sepkoski (2002) restricted its range to the Lower Jurassic (lower Hettangian—upper Pliensbachian), following Hallam (1977, 1987). The oldest record we accept here is Rhaetian, according to Ivimey-Cook and others (1999) and J. Yin and McRoberts (2006). Hodges (2000) considered that the genus was present from Carboniferous to Early Jurassic times, but we did not find any mention older than Rhaetian nor any paper quoting this genus before the Late Triassic. Hodges did not provide references to his statement, and thus it will not be taken into account here. The youngest record is from Toarcian beds (Liu, 1995; Fürsich & others, 2001).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 4). Tethys domain; Late Triassic; Rhaetian of Tibet (China) (J. Yin & McRoberts, 2006), northeastern England (Ivimey-Cook & others, 1999), southwestern United Kingdom (Mander, Twitchett, & Benton, 2008), southern Germany (Hodges, 2000); Early Jurassic; Germany and China (Hodges, 2000); Hettangian and Sinemurian of Europe (Hallam, 1976, 1977, 1987), eastern Asia and Australasia—Indonesia (Hallam, 1977), southwestern England (Hodges, 2000), southern England (Liu, 1995); Sinemurian of Portugal (Liu, 1995).

  • Circumpacific domain; Early Jurassic; Canada (Aberhan, 1998a), South America (Hodges, 2000), western Japan (Hodges, 2000).

  • Paleoautoecology.—B, D, Is, FM; Sb. According to Hodges (2000), Ryderia was a fast burrower. Puri in Cox and others (1969) mentioned a wide and shallow pallial sinus, but Hodges remarked that he did not observe such a feature in any of the specimens he studied, after making a thorough revision of the genus. Moreover, Hodges (2000, p. 45) indicated that “The lack of a pallial sinus and the extremely elongated rostrum suggest that the exposed siphons were short and that the tip of the rostrum lay just below the sediment surface.” Like other nuculanids, it was probably detritivorous.

  • Mineralogy.—Aragonitic (Carter, Lawrence, & Sanders, 1990, p. 313; Carter, Barrera, & Tevesz, 1998). Outer and middle shell layers; aragonite (?). Middle shell layer: aragonite (?).

  • Figure 5.

    Paleogeographical distribution of Ctenodontidae (Mesoneilo), Nudnellidae (Nucinella) and Solemyidae (Solemya). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f05_01.jpg

    Genus DACRYOMYA Agassiz, 1842–1844, p. 500

  • Type species.—Nucula lacryma J. de C. Sowerby, 1824, p. 119. Remarks.—Dacryomya is a particularly problematical genus for several reasons. For a long time this genus has been (and still is) regarded as a subgenus of Nuculana. Externally, it is very similar to other nuculanoids, such as Ryderia, Nuculana, or Phestia, and the differences between these genera and Dacryomya are often subjective when internal structures are not seen. For example, the four genera have a rostrate posterior, but in different degree: Ryderia has the longest rostrum, while Dacryomya has the shortest. Hodges (2000, p. 21) pointed out that Dacryomya is very similar to Ryderia and Nuculana and they can be confused, but Dacryomya “is distinguishable from Ryderia by its much greater inflation and shorter rostrum and from Nuculana by its much shorter rostrum and lack of marked ridges bordering the escutcheon.” Moreover, in Cox and others (1969, p. 239), Phestia was described as “Like Nuculana, but with prominent internal ridges,” but Dacryomya and Ryderia also have internal ridges. A thorough review of this genus is needed.

  • Furthermore, there is no consensus about the family affiliation of this genus: it was referred to Nuculanidae (Cox & others, 1969; Hayami, 1975), Nuculidae (Ivimey-Cook & others, 1999; Hodges, 2000) or Polidevciidae (Carter, 1990a; Delvene, 2000), where we provisionally include it.

  • Stratigraphic range.—Upper Triassic (Norian)—Upper Jurassic (Kimmeridgian) (Okuneva, 1985; Delvene, 2000). There are some Lower Triassic records of this genus (Nakazawa, 1961; Hayami, 1975), but they will not be taken into account here because Puri in Cox and others (1969) ignored them and assigned it a Middle Jurassic range. Carter (1990a) and Hodges (2000) regarded the first appearance as Lower Jurassic, but Ivimey-Cook and others (1999) reported it from the Rhaetian and Okuneva (1985) from Norian beds. Sepkoski (2002) assigned it a Lower Triassic—Lower Jurassic range, following Hayami (1975), but these data will not be taken into account due to the descriptive issues already mentioned. The youngest age accepted is Upper Jurassic, according to Delvene (2000).

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 4).

  • Tethys domain: Late Triassic: Rhaetian of England (Ivimey-Cook & others, 1999). Early Jurassic: England (Watson, 1982); Sinemurian of Europe (Hallam, 1976, 1977, 1987), England and Portugal (Liu, 1995), England, Germany, Switzerland, France, and Portugal (Hodges, 2000); Hettangian of China (Hodges, 2000).

  • Circumpacific domain: Early Jurassic: Japan (Goto, 1983). Boreal domain: Late Triassic: Norian of Transbaykal region (Siberia) (Okuneva, 1985). Early Jurassic: northern Siberia and Arctic region (Zakharov & others, 2006).

  • Paleoautoecology.—B, D, Is, FM; Sb. Similar to Palaeonucula. Mineralogy.—Aragonitic (Carter, 1990a, p. 153–156). Outer shell layer: aragonite (prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Superfamily CTENODONTOIDEA Wöhrmann, 1894
    Family CTENODONTIDAE Wöhrmann, 1894
    Genus MESONEILO Vu-Khuc, 1977a, p. 676

  • Type species.—Leda perlonga Mansuy, 1914, p. 82.

  • Remarks.—Vu Khuc (1977a) included this new genus in the family Ctenodontidae because it possesses a continuous hinge; in other words, the hinge is not interrupted below the umbo. He distinguished Mesoneilo from Phaenodesmia or Palaeoneilo because the first has opisthogyrous beaks and more teeth in the anterior part of the hinge. However, other authors included the type species of Mesoneilo in Nuculana (Gou, 1993; Hautmann, 2001b, p. 30) or in Phestia (Hautmann and others, 2005), but none of them mentioned Mesoneilo. A review of this species is needed to solve this question. Furthermore, some authors suggested that the family Ctenodontidae was exclusively Paleozoic and it is not well defined (Carter, 1990a); all these provide strong arguments to revise the familial affiliation of this genus.

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (Vu Khuc, 1977a). The genus was reported from Norian of northern Vietnam but a Norian to Rhaetian (Upper Triassic) range was given (Vu Khuc, 1977a). Later Okuneva (1985) referred a specimen from Norian beds of Siberia (Transbaykal region) to Mesoneilo perlonga, but she did not see its hinge and assigned it on the basis of its external shape alone. We think this assignation is very uncertain due to the external similarity with other nuculanoid genera.

  • Paleogeographic distribution.—Tethys and ?Boreal (Fig. 5).

  • Tethys domain: Late Triassic: China (Gou, 1993); Norian—Rhaetian of northern Vietnam, Laos, Burma, and southern China (Vu Khuc, 1977a; Vu Khuc & Huyen, 1998), Iran (Hautmann, 2001b).

  • ?Boreal domain: Late Triassic: Norian of Transbaykal region (northern Siberia) (Okuneva, 1985).

  • Paleoautoecology.—B, D, Is, FM; Sb. Similar to Nuculana.

  • Mineralogy.—Aragonitic (Carter, Barrera, & Tevesz, 1998). Data about the shell mineralogy of the genus and the family are not available. We assign an aragonitic mineralogy following Carter, Barrera, and Tevesz (1998) for subclass Protobranchia.

  • Superfamily MANZANELLOIDEA Chronic, 1952
    Family NUCINELLIDAE Vokes, 1956
    Genus NUCINELLA Wood, 1851 in 1851–1882, p. 72

  • Type species.—Pleurodon ovalis Wood, 1840, p. 230.

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Holocene (Vokes, 1956; McRoberts, Newton, & Allasinaz, 1995). The oldest record of Nucinella is N. liasina (Bistram, 1903) from Hettangian beds of the border between Switzerland and Italy (near lake Lucano) (Vokes, 1956). McRoberts, Newton, and Allasinaz (1995) mentioned the same species from Hettangian beds of the Lombardian basin (Alps). Cox and others (1969), as well as Skelton and Benton (1993) and Sepkoski (2002), agreed with the same time range.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 5). The genus is now widely distributed geographically (see Cox & others, 1969, p. 269), as it was during older times (e.g., Cretaceous of Georgia [Pojeta, 1988] or Japan [Amano, Jenkins, & Hikida, 2007]). Nevertheless, during the study interval, the genus was only reported from Italy. During the Toarcian, it was also reported from Germany and England (Aberhan, 1993; Harries & Little, 1999).

  • Tethys domain; Early Jurassic; Hettangian of Italy (Vokes, 1956; McRoberts, Newton, & Allasinaz, 1995).

  • Paleoautoecology.—B, D-Ch, Is, FM; Sb. Nucinella was a nonsiphonate, active burrower, as indicated by the lack of pallial sinus. It was most probably detritivorous, and it possibly had chemosymbiotic bacteria. According to Allen and Sanders (1969), at least the living species possesses large gills and tiny palps, similar to Solemya, which is not considered as detritivorous (S. M. Stanley, 1970). This suggests that Nucinella may have had a similar feeding habit, but the wide bathymetric range of the living species (between 9 and 900 m, though most live at approximately 400 m) challenges this assumption. The possibility that they have symbiotic relations with chemosynthetic bacteria is strongly supported by the fact that some living species do not even possess palps or intestine (e.g., N. viridula Kuznetzov & Schileyko, 1984, N. maxima (Thiele & Jaeckel, 1931) (Beesley, Ross, & Wells, 1998).

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 178). Outer shell layer: aragonite (prismatic). Middle and shell layers; aragonite (homogeneous).

  • Superfamily SOLEMYOIDEA Gray, 1840
    Family SOLEMYIDAE Gray, 1840
    Genus SOLEMYA Lamarck, 1818, p. 488

  • Type species.—Solemya mediterranea Lamarck, 1818, p. 488.

  • Remarks.—Cox and others (1969) regarded Janeia King, 1850, p. 177, as a subgenus of Solemya, but Pojeta (1988, p. 214–215) advised not to use that name since the generic concept lacks meaning. The genus Acharax Dall, 1908a, p. 2, is not included in the study interval, because no records from Triassic or Lower Jurassic deposits were found (see discussion in Genera not Included, p. 156).

  • Stratigraphic range.—Carboniferous (Upper Pennsylvanian)—Holocene (Pojeta, 1988). Cox and others (1969) assigned Solemya a Devonian—Holocene range, but Pojeta (1988) made an exhaustive revision of Paleozoic solemyoids and concluded that this genus extended from Pennsylvanian to Recent. We follow Pojeta, although other authors (Cope, 1997) extended its range back to the Devonian (Cope did not discuss this matter further), while others considered that the Paleozoic records are doubtful and regard the Jurassic as the first certain appearance (Imhoff & others, 2003; Little & Vrijenhoek, 2003). Ciriacks (1963) mentioned Solemya sp. from upper Permian deposits, but his assignation was only based on external shape. Seilacher (1990) described a new ichnofossil, Solemyatuba, that might be produced by Solemya or other related genera that live in a similar way. This ichnogenus has a wide distribution from Ordovician to Holocene (see Seilacher, 1990, p. 306–309). The only solemyoid genera known during Permian and Triassic times are Solemya and supposedly Acharax, and both have Recent representatives that are able to build Y-shaped tubes (S. M. Stanley, 1970; K. A. Campbell, Nesbitt, & Bourgeois, 2006); therefore, both are good candidates for Solemyatuba builders.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 5). During the time range of this review, Solemya was only reported from the Tethys, whereas it is mentioned from a wider geographic range at other moments of geologic time. Nevertheless, there is certain evidence (ichnogenus Solemyatuba) of its possible presence in Rhaetian beds of Germany and the Permian of Russia (Seilacher, 1990). During the middle Permian, it was reported from Russia and Siberia (Biakov, 2006; Ganelin & Biakov, 2006; Klets & others, 2006) and also from Middle and Late Jurassic from the Tethys (Fürsich, 1982; Komatsu, Saito, & Fürsich, 1993; Sha & Fürsich, 1994) and Austral domains (N. Hudson, 2003). There is a doubtful reference from the Late Triassic of Argentina (Damborenea & Manceñido, 2012).

  • Tethys domain; late Permian; Changhsingian of China (Teichert, 1990; M. Lin & Yin, 1991); Middle Triassic; Anisian of Hungary (Vörös & Pálfy, 2002); Early Jurassic; Germany (Seilacher, 1990).

  • Circumpacific domain; late Permian; Wyoming (United States) (Ciriacks, 1963).

  • Paleoautoecology.—B, Id, S-Ch, FM; Db. Solemya species have elongated and cylindrical shells with which they burrow deep Y-shaped tunnels (S. M. Stanley, 1970). Although their feeding behavior is not fully understood, and many strategies have been proposed: detritivorous (Cope, 1997), filter feeder (S. M. Stanley, 1970; Fürsich, 1982), or the use of both strategies (Liljedahl, 1984), it is clear that most of their food requirements are provided by chemosynthetic symbiotic bacteria (Cavanaugh, 1983). Many Holocene species have very small gut and palp proboscides (Reid, 1998) but have disproportionately large gills where they lodge the chemosymbiotic bacteria (Stewart & Cavanaugh, 2006). They live most of their life inside the Y-shaped tunnels and have a well-developed foot used for burrowing and swimming (Reid, 1998). In addition to the typical Y- or U-shaped galleries (described for Solemya), other types of burrows, such as I- and J-shaped, were attributed to Acharax (Campbell, Nesbitt, & Bourgeois, 2006). Even though they can swim, this is not their main mode of life; and the foot may also be functional to move inside their galleries (S. M. Stanley, 1970). The known species usually live in shallow water areas and are almost always associated with low-oxygen environments rich in sulfur and organic matter (S. M. Stanley, 1970; Pojeta, 1988; Seilacher, 1990). This habitat provides a barrier against oxygen-dependent predators (A. G. Fischer & Bottjer, 1995).

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 174). Outer shell layer: aragonite (prismatic). Middle and inner shell layers: aragonite (homogeneous).

  • Superfamily MYTILOIDEA Rafinesque, 1815
    Family MYTILIDAE Rafinesque, 1815
    Genus MODIOLUS Lamarck, 1799, p. 87

  • Type species.—Mytilus modiolus Linnaeus, 1758, p. 706.

  • Stratigraphic range.—Upper Devonian (Famennian)—Holocene (Cox & others, 1969). Modiolus is a long-ranging genus: having its origin in the Devonian, it is one of the oldest mussel genera with a good living representation (Cox & others, 1969). However, some authors believe that only Cenozoic to Holocene species should be referred to Modiolus (see Hodges, 2000).

  • Paleogeographic Distribution.—Cosmopolitan.

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. As suggested by comparison with living Modiolus species, most fossil species are thought to have been semi-infaunal and endobyssate (S. M. Stanley, 1970, 1972). There are many examples of fossil Modiolus found in life position that confirm that they were gregarious and lived semiburied and fixed by their byssus to pebbles and other hard objects buried in the sediment (Fürsich, 1980, 1982). The byssus emerges from the anterior part of the shell. They tend to inhabit intertidal and subtidal, high-energy environments (S. M. Stanley, 1970; Hodges, 2000). Seilacher (1984, p. 228–229), in his own terminology, qualified this genus as a “mud-sticker.”

  • Mineralogy.—Bimineralic (Hayami, Maeda, & Ruiz-Fuller, 1977; Carter, 1990a, p. 283). Outer shell layer: calcite (prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Figure 6.

    Paleogeographical distribution or Mytilidae (Promytilus, Inoperna, Falcimytilus, Lycettia, Lithophaga). 1, late Permian—Early Triassic; 2, Late Triassic—Early Jurassic.

    f06_01.jpg

    Genus PROMYTILUS Newell, 1942, p. 37

  • Type species.—Promytilus annosus Newell, 1942, p. 38.

  • Stratigraphic range.—Carboniferous (Mississippian)—Lower Triassic (Induan) (Newell, 1942; Waller & Stanley, 2005). Cox and others (1969) assigned Promytilus a Carboniferous (Mississippian)—Permian range; Sepkoski (2002) assigned it to the Carboniferous (Mississippian)—Permian (upper Guadalupian), following Hayami and Kase (1977). But these last authors mentioned several Promytilus species reported by Nakazawa and Newell (1968) from middle and upper Permian (Changhsingian) of Japan (Tenjinnoki and Gujo formations), although Hayami and Kase (1977, p. 86) only indicate upper Permian (stage unknown). Boyd and Newell (1997) considered Gujo Formation to be of upper Permian age. The presence of Promytilus in Lower Triassic deposits was mentioned by Waller (in Waller & Stanley, 2005) based on P. borealis Kurushin, the original reference is Kurushin (in Dagys & others, 1989). In his original proposal of the genus, Newell (1942) noted that some Triassic and Jurassic specimens attributed to Modiolus could belong to Promytilus instead.

  • Paleogeographic distribution.—Boreal (Fig. 6). Promytilus had a cosmopolitan distribution during Carboniferous and early Permian times, and lived in the Tethys domain in the late Permian (Wuchiapingian of China: Clapham, & Bottjer, 2007; Malaysia; Nakazawa, 1973), but during the study interval, we only found references from the Boreal domain.

  • Boreal domain: Early Triassic: Taimyr Peninsula (Russia) (Kurushin in Dagys & others, 1989).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to S. M. Stanley (1972), Promytilus represents an intermediate stage between Mytilus and Modiolus and most probably lived attached by its byssus to hard substrates in the intertidal zone, by analogy with the extant species “Modiolus” pulex (Lamarck, 1819), with which it has a great similarity (see fig. 8 and 9 in S. M. Stanley, 1972). As described by Newell (1942), Promytilus had a well-defined byssal sinus. According to Waller (in Waller & Stanley, 2005), Promytilus is mytiliform in most shell features but possesses an anterior lobe that is smaller and less developed than in Modiolus species.

  • Mineralogy.—Bimineralic (Newell, 1942; Nakazawa & Newell, 1968). Newell (1942) and Nakazawa and Newell (1968) indicated the presence of a calcitic outer shell layer with prismatic microstructure, but Carter (1990a) doubts that this was the original mineralogy. Outer shell layer: ?calcite (prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus INOPERNA Conrad in Kerr, 1875, p. 5

  • Type species.—Modiolus (Inoperna) carolinensis Conrad in Kerr, 1875, p. 5.

  • Stratigraphic range.—Upper Triassic (Rhaetian)—Upper Cretaceous (Maastrichtian) (Abdel-Gawad, 1986; Repin, 1996). Cox and others (1969) assigned it a Lower Jurassic (upper Liassic)—Upper Cretaceous range. However, findings referred to the subgenus Triasoperna Repin, 1996, p. 367 [7], indicate that the stratigraphic range of this genus should be extended back to the Upper Triassic (Repin, 1996; Hautmann, 2001b).

  • Paleogeographic distribution.—Tethys and ?Austral (Fig. 6). Although Inoperna was not widely distributed during our study interval, from Pliensbachian times and throughout all the Jurassic and Cretaceous, it had a cosmopolitan distribution (Freneix, 1965; Vörös, 1971; Hayami, 1975; Wen, 1982; Abdel-Gawad, 1986; Damborenea, 1987a; Liu, 1995; Holzapfel, 1998; Sha & others, 1998; Fürsich & others, 2001; Gahr, 2002; Delvene, 2003; Valls, Comas-Rengifo, & Goy, 2004).

  • Tethys domain: Late Triassic: Rhaetian of Iran (Repin, 1996; Hautmann, 2001b), northern Caucasus (Repin, 1996), Austria (Tomašových, 2006a, 2006b; Siblík & others, 2010); Early Jurassic: Hettangian of southwestern Great Britain (Hodges, 2000); Sinemurian of Portugal (Liu, 1995).

  • Austral domain: Early Jurassic: Hettangian—Sinemurian of Argentina (Damborenea, 1996a; Damborenea & Manceñido, 2005b).

  • Paleoautoecology.—B, Se, S, Endo, Sed; ?Bo. because Inoperna was referred to the subfamily Lithophaginae, several authors suggested the possibility that it was a borer (Damborenea, 1987a; Hodges, 2000; Hautmann, 2001b). However, Pojeta and Palmer (1976) warned that although its morphology is similar to the current Lithophaga, which has a borer mode of life, this particular life habit cannot be certain unless we find the specimens within their holes. In addition, one of those authors found Inoperna plicata J. Sowerby (Middle Jurassic of England) in life position that indicates a semi-infaunal habit. Hodges (2000, p. 64) compared Inoperna with members of the living genus Adula H. Adams & A. Adams, 1857 in 1854—1858, and he suggested that, like them, Inoperna could be a mechanical borer, boring into the substrate with its anterior part and then fixed inside it by the byssus. Most authors regard Inoperna as semi-infaunal endobyssate (Fürsich & others, 1995, 2001; Hautmann, 2001b; Gahr, 2002; Delvene, 2003).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 185). There is no information about Inoperna shell mineralogy. We use the data provided for the subfamily Lithophaginae.

  • Outer shell layer: calcite (homogeneous-prismatic). Middle shell layer: aragonite (nacreous). Inner shell layer: aragonite (nacreousprismatic).

  • Genus FALCIMYTILUS Cox, 1937c, p. 343

  • Type species.—Mytilus suprajurensis Cox, 1925, p. 142.

  • Stratigraphic range.—Upper Triassic (Carnian)—Upper Jurassic (Tithonian) (Kelly, 1984). Cox and others (1969) assigned it a Jurassic range, regardless of previous records that reported the genus from the Upper Triassic of Japan (Kobayashi & Ichikawa, 1950; Nakazawa, 1956; Hayami, 1958a). The latest undoubted record accepted here dates from Tithonian times (Kelly, 1984). Other authors, such as J. D. Taylor, Cleevely, and Morris (1983), mentioned Falcimytilus lanceolatus Sowerby from Lower Cretaceous (Albian), but they neither figured nor described the specimens, they just included them in a list of bivalve shells perforated by gastropods.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 6). During the study interval, the genus was known from the eastern Tethys, and later in the Jurassic, it was reported also from western Tethys (Hallam, 1976, 1996). The genus is often recorded from this area from Middle and Upper Jurassic beds (Fürsich, 1982; Kelly, 1984; Jaitly, 1988; Liu, 1995, 1999; Holzapfel, 1998; Sha & others, 1998).

  • Tethys domain: Late Triassic: Carnian—Norian of China (J. Chen, 1982a).

  • Circumpacific domain: Late Triassic: Carnian of Japan (Kobayashi & Ichikawa, 1950; Nakazawa, 1956; Hayami, 1975); Early Jurassic: Mexico (Damborenea in Damborenea & Gonzalez-León, 1997); Hettangian of Japan (Hayami, 1958a); Hettangian—Sinemurian of ?South America (Damborenea, 1996a).

  • Boreal domain: Late Triassic: northern Siberia (Dagys & Kurushin, 1985) and eastern Siberia (Kobayashi & Tamura, 1983b); Carnian of Primorie (Kiparisova, 1972); Norian of Russia (Zabaykal region) (Okuneva, 1985).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. As indicated by its mytiliform outline and its triangular cross section, Falcimytilus probably lived as epibyssate on hard substrates, as living Mytilus species do (Fürsich, 1982; Damborenea, 1987a).

  • Mineralogy.—Unknown (Carter, 1990a, p. 283; 1990b, p. 400). Outer shell layer: calcite and/or aragonite (?). Middle shell layer: aragonite (nacreous). Inner shell layer: aragonite (nacreous-prismatic).

  • Genus LYCETTIA Cox, 1937c, p. 345

  • Type species.—Mytilus lunularis Lycett, 1857, p. 128.

  • Stratigraphic range.—Lower Jurassic (Sinemurian)—Upper Cretaceous (Maastrichtian) (Cox & others, 1969; Damborenea, 1996a). Cox (1937c) proposed Lycettia and reported it from the Jurassic. Cox and others (1969) considered it was present in the Jurassic and Upper Cretaceous. This discontinuous range is due to the fact that Cuneolus Stephenson, 1941, p. 156, is regarded as a synonym of Lycettia in Cox and others (1969). The type species of Cuneolus (Dreissena tippana Conrad, 1858, p. 328) is typical from Upper Cretaceous beds (Carter, 1990a). Since then, the genus was also reported from Lower Cretaceous deposits (Hayami, 1975; Villamil, Kauffman, & Leanza, 1998; Komatsu & Maeda, 2005).

  • Paleogeographic distribution.—Austral (Fig. 6). During the earliest Jurassic, Lycettia was only present in the Austral Domain, but during the rest of the Jurassic, it was also reported from the Tethys (Damborenea, 1987a; Liu, 1995; Fürsich & others, 2001; Gahr, 2002).

  • Austral domain: Early Jurassic: Sinemurian of Argentina (Damborenea, 1996a; Damborenea & Manceñido, 2005b; Damborenea & Lanés, 2007).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Lycettia presents some characters that indicate an epibyssate mode of life: external shape triangular in lateral view, the absence of anterior lobe and triangular cross section (S. M. Stanley, 1972). These features are taken to the extreme in this genus, which most probably lived fixed by the byssus to hard substrates in high-energy environments (Damborenea, 1987a). These hard substrates may be other bivalve shells, as Myoconcha from Middle Jurassic (Damborenea, 1987a), or Steinmanella quintucoensis (Weaver) from the Lower Cretaceous (Villamil, Kauffman, & Leanza, 1998).

  • Mineralogy.—Aragonitic (Carter, 1990b, p. 395–396). Outer shell layer: aragonite (prismatic). Middle shell layer: aragonite (nacreous). Inner shell layer: aragonite (prismatic-nacreous).

  • Genus LITHOPHAGA Röding in Bolten, 1798, p. 156

  • Type species.—Mytilus lithophagus Linnaeus, 1758, p. 705.

  • Stratigraphic range.—Upper Triassic (Norian)—Holocene (Kleemann, 1994). Cox and others (1969) considered the reports of this genus from Carboniferous age to be doubtful, and thus they attributed it a continuous range from Miocene to Recent. These doubtful data are surely from Newell (1942), who pointed out that, although Lithophaga was not very common in the Paleozoic, several species were described from Carboniferous and Permian beds around the world. However, Kleemann (1990) argued that the specimens attributed to Lithophaga from Carboniferous and Triassic age are indeed more than doubtful: they are externally similar to Lithophaga, but they probably did not have an endolithic mode of life. Kleemann (1994) and Carter and Stanley (2004) found specimens of Lithophaga in life position in holes bored inside Upper Triassic corals (as happens in many living species). Since the presence of Lithophaga in pre-Upper Triassic sediments cannot be assured, we will consider that the genus ranges from Upper Triassic to the present. Linck (1972) reported Lithophaga sp. cf. vermiculata Linck from Carnian beds, but he only assigned his specimen to Lithophaga on the basis of its external features, and he did not find it in life position, so we cannot really be sure that it was Lithophaga. Ivimey-Cook and others (1999) found borings that could belong to Lithophaga in Rhaetian deposits from England.

  • Paleogeographic distribution.—Tethys (Fig. 6). If finding specimens within their borings is a prerequisite to refer them to Lithophaga, then it is very difficult to know what the actual distribution of the genus was. In our study interval, it was reported from Tethys, but at other times (and also Recent), it had a cosmopolitan distribution (Cox & others, 1969).

  • Tethys domain: Late Triassic: Norian of Germany (Carter & Stanley, 2004); Rhaetian of Austria (Kleemann, 1994; Carter & Stanley, 2004), Iran (Hautmann, 2001b).

  • Paleoautoecology.—B, Is, S, By, Sed; Bo. Living Lithophaga species are borers in hard substrates, especially in dead and live coral skeletons (Kleemann, 1994; Scott, 1988). They are regarded as chemical borers, because they disaggregate the substrate with the aid of special chemical substances, although it appears that in some species, like Lithophaga nigra (d'Orbigny, 1853), this is supplemented by mechanical boring (L. Fang & Shen, 1988). Regarding fossil species, Lithophaga shells are reported in coral boreholes (Kleemann, 1994; Waller & Stanley, 2005), so the same mode of life is assumed for them. Savazzi (2001) mentioned a possible macrosymbiotic relationship between Lithophaga species burrowing into live corals and the corals themselves, as the coral provides protection and reduces competition with other borers that only bore on nonliving substrates. There is no evidence that the bivalve uses the coral as a food source.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 285). Outer shell layer: calcite (homogeneous-prismatic). Middle shell layer: aragonite (nacreous). Inner shell layer: aragonite (nacreous-prismatic).

  • Family MYSIDIELLIDAE Cox, 1964

  • Although Hautmann (2008) proposed that this family should be included in the superfamily Ambonychioidea, we follow Cox and others (1969), Carter (1990a), Amler (1999), Amler, Fischer, and Rogalla (2000), Waller and Stanley (2005), and Bouchet and Rocroi (2010) to refer it to the Mytiloidea (see discussions in Hautmann, 2001b, 2008; Waller & Stanley, 2005). Some disagreement has arisen in recent years about which genera should be included in this family, and this is summarized below.

  • Cox (1964) proposed the family and included within it Protopis Kittl, 1904, p. 718 (=Joannina Waagen, 1907, p. 94) and two new genera, Mysidiella Cox, 1964, p. 44 (pro Mysidia Bittner, 1891, p. 113, non Westwood, 1840) and Tommasina Cox, 1964, p. 44 (nom. nov. for Mytiliconcha Tommasi, 1911, non Mytiloconcha Conrad, 1862). Waller (in Waller & Stanley, 2005) proposed the synonymy Protopis (= Tommasina) and advised the exclusion of Protopis and its synonyms (Joannina and Tommasina) from the family Mysidiellidae, but he did not suggest a new allocation. Waller (in Waller & Stanley, 2005) proposed the inclusion of Botulopsis Reis, 1926 (emended by him) and his new genus Promysidiella Waller in Waller & Stanley, 2005. Stiller and Chen (2006), following Cox but without mentioning Waller's paper (in Waller & Stanley, 2005), added to the genera in the family (Protopis, Mytiliconcha, and Mysidiella), their three new genera from the Anisian of China: Leidapoconcha Stiller & Chen, Waijiaoella Stiller & Chen, and Qingyaniola Stiller & Chen. These authors regarded the name Mytiliconcha as valid, and, since Conrad's and Tommasi's names differ in one letter, we agree with Vokes (1980) in regarding Tommasina as an unnecessary name.

  • On the other hand, Hautmann (2008) proposed the new family Healeyidae, which includes Healeya Hautmann, 2001b, Joannina (which he regarded as valid for substantial differences with Protopis), and, with some hesitation, Protopis and the three genera created by Stiller and Chen (2006): Leidapoconcha, Waijiaoella, and Qingyaniola. In turn, he suggested that Mysidiella, Promysidiella, and Botulopsis should remain in Mysidiellidae, following Waller (in Waller & Stanley, 2005), but including this family within the Ambonychiodea. Hautmann (2008) based these conclusions on the study of the microstructure of one of his specimens of Mysidiella imago Hautmann, 2001b, where he found that the outer shell layer was subdivided into several sublayers (from outside to inside); prismatic, foliar, and coarsely prismatic. He argued that the foliar sublayer and the size of the prisms of the outer sublayer support an origin from myalinids rather than from mytilids. Nevertheless, although no microstructure studies are known for Promysidiella cordillerana (Newton), Newton (in Newton & others, 1987, fig. 13, p. 16) proposed that “abraded specimens exhibit an inner, very fine radial structure, representing silica replacement of primary fibrous prismatic microstructure, homologous to that occurring in outer ostracum of modern Mytilus, as well as Permian mytiloids (Newell, 1942).”

  • Waller (in Waller & Stanley, 2005) differentiated Mysidiellidae from Myalinidae, because they had different microstructure in the outer shell layers (fibrous prismatic and columnar prismatic, respectively) and different types of ligament (opisthodetic and duplivincular, respectively). But he did not study the microstructural shell details under the electronic microscope, and based his assumption on; “it superficially appears very similar to the microstructure of the outer shell layer of many modern mytilids” (Waller in Waller & Stanley, 2005, p. 8). Hautmann's (2008) proposal seems more solidly supported because it is based on microstructural studies and also on the revision of holotypes and several collections but, in our view, a lot of work is still needed to clarify this question. It is evident that the problems of this family are far from settled, and we therefore include all related genera in this family without further systematic discussions.

  • We follow Waller and Stanley (2005) and Stiller and Chen (2006) in the allocation of their genera into Mysidiellidae, and we also maintain the inclusion of Protopis and its synonyms. Meanwhile, in the absence of new studies, we believe it is still risky to accept the new family proposed by Hautmann (2008) with its original generic composition. We regard Joannina as a valid genus, following Hautmann (2008).

  • Genus MYSIDIELLA Cox, 1964, p. 44

  • nom. nov. pro Mysidia Bittner, 1891, non Westwood, 1840, p. 83

  • Type species.—Mysidia orientalis Bittner, 1891, p. 113.

  • Stratigraphic range.—Upper Triassic (Carnian—Rhaetian). Cox and others (1969) assigned this genus a Ladinian—Rhaetian range, as did also Sepkoski (2002) and Stiller and Chen (2006). The Ladinian record surely refers to Mysidia taramellii De Toni, 1913, because it is the only one from that stage (data from Diener, 1923); but Waller (in Waller & Stanley, 2005), in his revision of family Mysidiellidae and based on the illustrations provided by De Toni, assigned this species to Botulopsis Reis, 1926, p. 124. Moreover, they also considered that Mysidiella cordillerana Newton in Newton and others, 1987, p. 16, and Mysidiella americana (Körner, 1937) should belong to Promysidiella Waller in Waller & Stanley, 2005, p. 10. They renamed the specimens described by Newton (in Newton & others, 1987) as Krumbeckiella sp. cf. timorensis (Krumbeck, 1924) as their new species Mysidiella newtonae Waller & Stanley, 2005. Szente and Vörös in Budai and others (2003) reported ?Mysidiella sp. from Anisian beds, but this will not be taken into account because the material was not figured.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 7).

  • Tethys domain: Late Triassic: Carnian of Greece (Diener, 1923), China (Wen & others, 1976); Norian of Turkey (Diener, 1923), China (Kobayashi & Tamura, 1983a); Norian—Rhaetian of Iran (Hautmann, 2001b).

  • Circumpacific domain: Late Triassic: Carnian of British Columbia (Waller & Stanley, 2005), of Japan (Nakazawa, 1994); Norian of Oregon, United States (Wallowa Terrane) (Waller & Stanley, 2005).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The deep byssal notch (see diagnosis in Waller & Stanley, 2005) present in species attributed to this genus indicates an epibyssate mode of life. Their external morphology is similar to mytilid shells, and thus they probably lived in high-energy environments (Newton in Newton & others, 1987). The anterior part of the valves is flat, suggesting the animal lived orthothetically rested, i.e., with the commissure at a nearly right angle to the substrate surface (Hautmann, 2001b, 2008).

  • Mineralogy.—Bimineralic (Hautmann, 2008). According to Hautmann (2001b), the outer shell layer consists of foliated calcite, but Waller (in Waller & Stanley, 2005) did not find evidence of this type of microstructure in their specimens referred to Mysidiella species. Hautmann (2008), following a suggestion by Waller (in Waller & Stanley, 2005), studied the microstructure in tangential section (rather than in radial section, as he had done previously: Hautmann, 2001b) and found that the outer shell layer of Mysidiella imago Hautmann, 2001b, had several sublayers with prismatic, foliar, and coarsely prismatic microstructure (from outer to inner sublayers). Outer shell layer: calcite (prismatic). Middle and inner shell layers: aragonite (?).

  • Figure 7.

    Paleogeographical distribution or Mysidiellidae (Mysidiella, Botulopsis, Promysidiella, Protopis, Joannina, Leidapoconcha, Waijiaoella, Qingyaniola). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f07_01.jpg

    Genus BOTULOPSIS Reis, 1926, p. 124

  • Type species.—Botulopsis reisi Waller in Waller & Stanley, 2005, p. 13 [=Botulopsis cassiana Reis, 1926, non Botulopsis cassiana (Bittner, 1895)].

  • Remarks.—We include Botulopsis in Mysidiellidae following Waller (in Waller & Stanley, 2005).

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Carnian) (Waller & Stanley, 2005). Cox and others (1969) assigned this genus an Upper Triassic range; Sepkoski (2002) considered Botulopsis present in Lanidian and Carnian times, based on data provided by Hallam (1981). Waller (in Waller & Stanley, 2005) emended the generic diagnosis and renamed the type species Botulopsis cassiana Reis, 1926, as Botulopsis reisi Waller in Waller & Stanley, 2005, present in Ladinian beds. Furthermore, Waller (in Waller & Stanley, 2005) included other two species within the genus: Botula? cassiana Bittner, 1895 (Carnian) and Mysidia taramellii De Toni, 1913 (Ladinian). Hautmann (2008) pointed out that Botulopsis was reported from Rhaetian deposits of Germany, and if that reference is correct, the range for this genus should be extended. Stiller (2001) mentioned Botulopsis cassiana from the Anisian of China, but this assignation is wrong (Stiller, personal comnunication, 2008).

  • Paleogeographic distribution.—western Tethys (Fig. 7).

  • Tethys domain: Middle Triassic: Ladinian of Austria (Kutassy, 1931), Italy (Reis, 1926; Waller & Stanley, 2005); Late Triassic: Carnian of the Alps (Bittner, 1895; Diener, 1923; Waller & Stanley, 2005).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Botulopsis was probably an epibyssate bivalve, on account of its external shell shape, which is quite inflated, and its shallow byssal gape, but possibly it did not inhabit high-energy environments, as Mysidiella did.

  • Mineralogy.—Bimineralic (Waller & Stanley, 2005). Botulopsis shell microstructure is not known; data used here are taken from the diagnosis of the family Mysidiellidae in Waller and Stanley (2005). Outer shell layer: calcite (fibrous prismatic). Middle and inner shell layers: aragonite (?).

  • Genus PROMYSIDIELLA
    Waller in Waller & Stanley, 2005, p. 10

  • Type species.—Mysidiella cordillerana Newton in Newton & others, 1987, p. 16.

  • Stratigraphic range.—Middle Triassic (lower Anisian)—Upper Triassic (lower Norian) (Waller in Waller & Stanley, 2005; Newton in Newton & others, 1987). The type species comes from lower Norian beds, but Waller (in Waller & Stanley, 2005) included also the following species: Mysidia americana Körner, 1937, Mytilus eduliformis Schlotheim, 1820, Mytilus otiosus McLearn, 1947, and two new species: Promysidiella planirecta Waller in Waller & Stanley, 2005, and P. desatoyensis Waller in Waller & Stanley, 2005. Waller (in Waller & Stanley, 2005) also pointed out that some species attributed to Mytilus Linnaeus, 1758, from the European Muschelkalk could be included in Promysidiella. In the same paper (Waller in Waller & Stanley, 2005, p. 10), he assigned it a Lower Triassic (Spathian)—Upper Triassic (Norian) range, but this is probably an error, because in the discussion he said, “… the oldest known Promysidiella, P. eduliformis (Schlotheim, 1820) from the lower Middle Triassic.” Hautmann (2008) stated that eduliformis did not appear until early Anisian. There is, however, a Lower Triassic record of this species, although its systematic affiliation needs confirmation: Z. Yang & Yin (1979) mentioned Mytilus eduliformis from the upper Scythian Shihchienfeng Group of Shaanxi province (northern China), and Hautmann and others (2011) mentioned Promysidiella? sp. from southern China.

  • Paleogeographic distribution.—Tethys, Circumpacific, and ?Boreal (Fig. 7).

  • Tethys domain: Middle Triassic: Anisian—Ladinian of Spain (Mallada, 1880; Schmidt, 1935; Virgilli, 1958; Márquez-Aliaga, 1983, 1985; Budurov & others, 1991), Italy (Posenato, 2002; Posenato & others, 2002), Germany (Urlichs, 1992), Jordan (Hautmann, 2008); Late Triassic: China (Gou, 1993), Germany (Warth, 1990).

  • Circumpacific domain: Middle Triassic: Ladinian of Nevada (United States) (Waller & Stanley, 2005); Late Triassic: Carnian of Peru (Körner, 1937), British Columbia (Canada) (Waller & Stanley, 2005); early Norian of Oregon (United States) (Newton, 1986; Newton & others, 1987).

  • ?Boreal domain: Middle Triassic: Anisian of northern Siberia (Dagys & Kurushin, 1985), although we should check if this is taxonomically correct.

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Newton (in Newton & others, 1987) suggested that the type species was epibyssate with a life style similar to Recent mytilids; based on its external shape, she inferred that it probably lived on hard substrates in high-energy open environments. Some species, such as P. desatoyensis, probably lived gregariously as the living Mytilus edulis Linnaeus does, according to taphonomic analysis of several individuals found in proximity to each other (Waller in Waller & Stanley, 2005). Waller (in Waller & Stanley, 2005) also argued that this species could have had a pendent mode of life, because some features (broad and flat anterior part, anterior margin concave, deep byssal invagination, and byssal notch) indicate that it was strongly attached by the byssus. However, he also suggested an epibyssate mode of life on hard substrates, but solitary (i.e., not forming clusters) for another species, P. planirecta.

  • Mineralogy.—Bimineralic (Newton in Newton & others, 1987, p. 16; Carter, 1990a, p. 286; Waller & Stanley, 2005, p. 10; but see Hautmann, 2008, p. 556). Outer shell layer: calcite (fibrous prismatic). Middle and shell layers: aragonite (?).

  • Genus PROTOPIS Kittl, 1904, p. 718

  • Type species.—Opis (Protopis) triptycha Kittl, 1904, p. 718.

  • Remarks.—We regard Mytiliconcha Tommasi, 1911 (=Tommasina Cox, 1964) as a synonym of Protopis following Waller (in Waller & Stanley, 2005) (see discussion for Tommasina in Genera not Included, p. 171). Waller (in Waller & Stanley, 2005, p. 9) removed Protopis from the Mysidiellidae and this was further discussed by Hautmann (2008, p. 559), who reillustrated the original specimens of the type species and placed Protopis within the Modiomorphoidea (p. 562).

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Waller & Stanley, 2005; Hautmann, 2008). Hautmann (2008) reviewed the genus Protopis and included there only the type species. Some species traditionally placed within this genus were transferred to Joannina by the author (see discussion for Joannina below). Therefore he assigned the genus to the Anisian. However, he did not refer to other species, as Protopis qinghaiensis Wen, from Carnian—Norian of Qinghai (data provided by Stiller & Chen, 2006). These authors suggested that this species might be included in Waijiaoella Stiller & Chen, 2006, based on its overall shape, but they noted a revision was needed. Waller (in Waller & Stanley, 2005) included Tommasina Cox, 1964 (see discussion in Genera not Included, p. 171) as a synonym of Protopis. Tommasina, or more correctly Mytiliconcha Tommasi, 1911, p. 35 (see Vokes, 1980), is also monospecific, including only the type, Mytiliconcha orobica Tommasi, 1911, from Carnian beds (Cox, 1964; Cox & others, 1969; Stiller & Chen, 2006). Waller (in Waller & Stanley, 2005) indicated its presence in Ladinian times, but this is most probably an error, because the only data source is Tommasi, 1911. Skelton and Benton (1993, p. 243) mentioned as first appearance of the family Mysidiellidae Protopis triptycha Kittl, 1904, from Scythian of the Werfen layers in the Austrian Alps, but it is not possible to verify this record because the authors did not indicate the original source.

  • Paleogeographic distribution.—Tethys (Fig. 7).

  • Tethys domain: Middle Triassic: Anisian of the Balkans (Hautmann, 2008); Late Triassic; Carnian of the Alps (Italy) (Cox, 1964; Cox & others, 1969; Stiller & Chen, 2006), China (Stiller & Chen, 2006) .

  • Paleoautoecology.—B, E, S, Epi, Sed; By. We assign this genus an epibyssate mode of life, like most mysidiellids. The species here recognized within Protopis are Opis (Protopis) triptycha Kittl, 1904 (type species of Protopis) and Mytiliconcha orobica Tommasi, 1911 (type species of Tommasina, considered synonym of Protopis). These species lack the typical anterior lobe of Joannina species and show morphological features similar to other Mysidiellidae, so we suggest they had the same mode of life.

  • Mineralogy.—Bimineralic(?). There are no data about shell mineralogy and microstructure of this genus. Provisionally, we assign it bimineralic mineralogy.

  • Genus JOANNINA Waagen, 1907, p. 94

  • Type species.—Joannina joannae Waagen, 1907, p. 94.

  • Remarks.—Krumbeck (1924) included Joannina as a synonym of Protopis and Cox (1964) and Cox and others (1969), among others, accepted this situation, which Waagen (1907) already suspected (Hautmann, 2008). However, Hautmann (2008, p. 559–560) revised the holotypes of the type species of Joannina and Protopis, and he found differences that justify the separation of both genera. This author included within Joannina its type species and tentatively Protopis timorensis Krumbeck, 1924, from the Lower Triassic of Timor, Joannina waageni Schnetzer, 1934, and Joannina aberrans Schnetzer, 1934, both from the Anisian of Austria.

  • Stratigraphic range.—Lower Triassic (?Induan)—Upper Triassic (Carnian) (Krumbeck, 1924; Stiller & Chen, 2006). The oldest record is from the Lower Triassic (Krumbeck, 1924), and the youngest, Protopis joannae, from Carnian beds (Waagen, 1907; Stiller & Chen, 2006). This species was also mentioned by Hautmann (2008) from Ladinian [data provided by Waagen, 1907], and although Kochanová, Mello, and Siblík (1975, pl. 8,5) mentioned Protopis sp. cf. joannae from the Carnian of the Carpathians, the figured material is only a very poorly preserved fragment, not enough to ascertain if it really belongs to this species. Sha, Chen, and Qi (1990) also mentioned Protopis? sp. cf. P. timorensis Krumbeck, but according to Stiller and Chen (2006), this specimen is badly preserved and thus of doubtful relationship.

  • Paleogeographic distribution.—Tethys (Fig. 7).

  • Tethys domain; Early Triassic: ?Induan of Timor (Krumbeck, 1924); Middle Triassic: Anisian of Austrian Alps (Hautmann, 2008), China (Komatsu, Chen, & others, 2004), Hungary (Szente & Vörös in Budai & others, 2003); Ladinian of the Alps (Hautmann, 2008); Late Triassic: Carnian of the Alps (Stiller & Chen, 2006).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. According to Hautmann (2008, fig. 5), one of the main differences between Joannina and Protopis is that the former has a distinct anterior lobe. Furthermore, he pointed out that Joannina is modioliform, and thus he suggested an endobyssate mode of life, with the byssus emerging “between this anterior shell lobe and the main body of the shell, a faint radial shell fold creates a gape between both valves for the passage of the byssus” (Hautmann, 2008, p. 559, and see his fig. 5.1). Joannina is externally similar to Leidapoconcha, which probably had also an endobyssate mode of life.

  • Mineralogy.—Bimineralic(?). Joannina shell mineralogy or microstructure has not been studied. Due to the taxonomic problems already discussed, we cannot refer to the predominant mineralogy in the family (see explanation in Mineralogy of Leidapoconcha below). We provisionally assign it bimineralic mineralogy.

  • Genus LEIDAPOCONCHA Stiller & Chen, 2006, p. 215

  • Type species.—Leidapoconcha gigantea Stiller & Chen, 2006, p. 216.

  • Stratigraphic range.—Middle Triassic (Anisian) (Stiller & Chen, 2006). Leidapoconcha has only been reported from sediments dated as lower upper Anisian (Stiller & Chen, 2006). It is a monotypic genus.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 7).

  • Tethys domain: Middle Triassic: Anisian of southwestern China (Guizhou) (Stiller & Chen, 2006).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. According to the environment suggested for the deposits where Leidapoconcha, Waijiaoella, and Qingyaniola were found, they lived in fully marine, shallow water, and low-energy settings (Stiller & Chen, 2006). The authors also suggested an endobyssate or epibyssate mode of life for these genera, on the basis of their external morphology, since all of them have byssal gapes. Nevertheless, we think that a semi-infaunal, endobyssate, and sedentary mode of life is more feasible, similar to that proposed for Healeya by Hautmann (2001b).

  • Mineralogy.—Bimineralic(?). No data about the shell mineralogy and microstructure of this genus are available. Both Waller (in Waller & Stanley, 2005) and Hautmann (2008) agree that the family Mysidiellidae probably had a bimineralic shell, with calcitic outer shell layer and ar agonitic middle and inner layers, but they disagree about the outer shell layer microstructure. However, Hautmann (2008) included Leidapoconcha, Waijiaoella, and Qingyaniola in his new family Healeyidae. No microstructural studies have been done on its type genus (Healeya), but an original aragonitic mineralogy is suggested by the fact that the shell is often found completely recrystallized (Hautmann, 2008). Stiller and Chen (2006) indicated the presence of recrystallized calcite in the shell of the specimens they studied.

  • Figure 8.

    Paleogeographical distribution of Parallelodontidae (Macrodontella, Catella, Grammatodon, Bapristodia). 1, late Permian; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f08_01.jpg

    Genus WAIJIAOELLA Stiller & Chen, 2006, p. 218

  • Type species.—Waijiaoella elegans Stiller & Chen, 2006, p. 219.

  • Stratigraphic range.—Middle Triassic (Anisian) (Stiller & Chen, 2006). Waijiaoella was only reported from sediments dated as lower upper Anisian (Stiller & Chen, 2006). The genus includes two species, the type and Waijiaoella speciosa Stiller & Chen, 2006.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 7). See Leidapoconcha (p. 26).

  • Paleoautoecology.—B, Se, S, Endo, Se. See Leidapoconcha (p. 26).

  • Mineralogy.—Bimineralic(?). See Leidapoconcha (p. 26).

  • Genus QINGYANIOLA Stiller & Chen, 2006, p. 222

  • Type species.—Qingyaniola mirabilis Stiller & Chen, 2006, p. 223.

  • Stratigraphic range.—Middle Triassic (Anisian) (Stiller & Chen, 2006). See Leidapoconcha (p. 26).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 7). See Leidapoconcha (p. 26).

  • Paleoautoecology.—B, Se, S, Endo, Se. See Leidapoconcha (p. 26).

  • Mineralogy.—?Bimineralic. See Leidapoconcha (p. 26).

  • Superfamily ARCOIDEA Lamarck, 1809
    Family PARALLELODONTIDAE Dall, 1898

  • Newell in Cox and others (1969, p. 256) pointed out that the phylogeny of this group is not well known, and several decades later, the problems to distinguish their genera still persist, although many authors have recently discussed this topic (see e.g., Damborenea, 1987a; Amler, 1989; Carter, 1990a; Stiller, 2006). The trouble is mainly focused on Parallelodon Meek & Worthen, 1866, Grammatodon Meek & Hayden, 1860, and Cosmetodon Branson, 1942. The general shell shape, the teeth (especially their arrangement), and ornamentation are features that were commonly used as criteria to distinguish these taxa (Manceñido, González, & Damborenea, 1976). Although it seems that the orientation of hinge teeth is a good criterion, it is not enough, since, as has been shown, in some Parallelodon species, the teeth may change their orientation during ontogeny (Newton in Newton & others, 1987; Hautmann, 2001b). In this regard, Stiller (2006, p. 12) concluded that “the convergence direction of the long posterior pseudolaterals appears to be taxonomically more reliable than the direction of the short anterior cardinals; the anterior ends of the posterior teeth intersect the dorsal shell margin in the Parallelodontinae and the ventral margin of the hinge plate in the Grammatodontinae.” The difficulty of applying these criteria is that hinge teeth are not observed in most specimens. A thorough review of this family is needed, but it is beyond the scope of this paper.

  • Genus MACRODONTELLA Assmann, 1916, p. 616

  • Type species.—Macrodontella lamellosa Assmann, 1916, p. 616.

  • Remarks.—Although Assmann (1916) included Macrodontella in the family Arcidae, we follow Newell in Cox and others (1969) and later authors (e.g., Sha, Chen, & Qi, 1990) and refer it to the Parallelodontidae.

  • Stratigraphic range.—Middle Triassic (Anisian). Assmann (1916) described this monotypic genus from lower Muschelkalk (probably Anisian) from the Erzführender Dolomit Formation in Silesia (Poland). Cox and others (1969) assigned it a Middle Triassic range. Macrodontella was reported from middle Anisian beds from Poland (Malinowskiej, 1979). The genus was also doubtfully recorded from Chinese Anisian deposits (Sha, Chen, & Qi, 1990).

  • Paleogeographic distribution.—Tethys (Fig. 8).

  • Tethys domain: Middle Triassic: Poland (Assmann, 1916; Cox & others, 1969), Anisian of Poland (Malinowskiej, 1979), China (?Qinghai province) (Sha, Chen, & Qi, 1990).

  • Paleoautoecology.—B, E-Se, S, Epi-Endo, Sed; By. Sha, Chen, and Qi (1990) suggested an epibyssate and suspensivorous mode of life; however, Aberhan and others (2004) assigned it a semi-infaunal mode of life. Because it is a monotypic genus with reduced distribution, it is difficult to obtain good illustrations to help settle this question.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 189). No data about shell mineralogy-microstructure of Macrodontella are available. Data provided for the family Parallelodontidae (Carter, 1990a).

  • Genus CATELLA Healey, 1908, p. 13

  • Type species.—Gramatodon (Catella) laticlava Healey, 1908, p. 13.

  • Stratigraphic range.—Upper Triassic (Carnian)—Lower Paleogene (Danian) (Wen & others, 1976; Heinberg, 1999). Healey (1908) described Catella as a subgenus of Grammatodon from the Rhaetian of Burma. Cox and others (1969) assigned it an Upper Triassic—Jurassic range, and Sepkoski (2002) assigned a Triassic (Norian)—Paleocene (Thanetian) range, and presumably got his data from Heinberg (1978), but in this last paper, the figure with the ranges of genera seems to indicate Danian, not Thanetian. The youngest record is Paleocene (Danian) (Heinberg, 1999), because we were not able to corroborate the range offered by Sepkoski (2002). The oldest record considered for almost all authors for Catella is Norian (Wen & others, 1976; Hallam, 1981; J. Zhang, 1983; Hautmann, 2001b). Nevertheless, Guo (1988) proposed a new subgenus, Catella (Oceanopieris), from the Carnian of Yunnan (China), which was considered a junior synomym of Catella by Z. Fang and others (2009). Catella shows a seemingly discontinuous distribution through time. Although it was widely mentioned from the Upper Triassic (see next section), it is not reported again until the Upper Jurassic (X. Li, 1990; Monari, 1994) and later in the Upper Cretaceous (Heinberg, 1999).

  • Paleogeographic ditribution.—Eastern Tethys (Fig. 8).

  • Tethys domain: Late Triassic: Carnian of Yunnan (China) (Guo, 1988); Norian of Yunnan (China) (J. Zhang, 1983), Himalaya (southern Tibet) (Wen & others, 1976; J. Yin & Enay, 2000; Hautmann, 2001b); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Burma (Healey, 1908), Indochina (Kutassy, 1931).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Several aspects of the shell shape, such as the reduced anterior part of the shell, absence of ventral flattening, external modioliform appearance, and presence of byssal sinus, suggest that Catella was probably an endobyssate semi-infaunal bivalve (Heinberg, 1999; Hautmann, 2001b).

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 184–185). There are no data about Catella shell mineralogy or microstructure. Data provided for superfamily Arcoidea.

  • Genus PARALLELODON Meek & Worthen, 1866, p. 17
    nom. nov. pro Macrodon Buckman [Lycett MS] in Murchison, Buckman, & Strickland, 1844, non Schinz, 1822, p. 482, nec
    Müller, 1842, p. 308

  • Type species.—Macrodon rugosus Buckman in Murchison, Buckman, & Strickland, 1844, p. 99.

  • Stratigraphic range.—Middle Devonian—Upper Cretaceous (Amler & Winkler Prins, 1999). Traditionally, all Paleozoic members of the family Parallelodontidae were referred to Parallelodon (Newell in Cox & others, 1969); however, Manceñido, González, and Damborenea (1976) and Yancey (1985) noticed that many of these species should be referred to Grammatodon (Cosmetodon) instead. The same happens with some Mesozoic species referred to Parallelodon, which would better be allocated in Grammatodon (Grammatodon) (Damborenea, 1987a). Many Paleozoic species were described based on poorly preserved material or with little morphological discussion (Amler, 1989; Anelli, Rocha-Campos, & Simões, 2006). In practice, it is hard to distinguish between Parallelodon and Grammatodon (Boyd & Newell, 1979). For this reason, the range assigned here is provisional for these two genera, awaiting revision of Paleozoic material.

  • Paleogeographic distribution.—Cosmopolitan.

  • Paleoautoecology.—B, E, S, Epi, Sed; By. There are endobenthic and epibenthic species within this genus (S. M. Stanley, 1972). Those with a modioliform appearance are presumably endobyssate. Others are quadrangular and morphologically very similar to epifaunal Recent arcids. Some species, such as P. monobensis Nakazawa, 1955, have a large ventral sinus indicating an epibyssate mode of life. Other species, such as P. groeberi Damborenea, 1987a, and P. riccardii Damborenea, 1987a, were also epifaunal and probably attached to hard substrates with a strong byssus, as living Area species do (S. M. Stanley, 1970; Damborenea, 1987a). Parallelodon riccardii might even have been a nestler (Damborenea, 1987a), as suggested by its elongated and laterally compressed shell (Thomas, 1978). However, P. tenuistriatus (Meek & Worthen, 1866) and P. hirsonensis (Archiac, 1843) were probably endobyssate (Quiroz-Barroso & Perrilliat, 1998; Fürsich & others, 2001). They are often found associated with corals and sponges (Damborenea, 1987a; Newton in Newton & others, 1987). But they could also live attached on rocks in open substrates (Newton in Newton & others, 1987). J. Yin and McRoberts (2006) suggested that representatives of the genus had an epibyssate and suspensivorous mode of life. We assign Parallelodon the predominant mode of life of species attributed to this genus.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 189–190). Outer shell layer: aragonite (prismatic). Middle shell layer: aragonite (cross-lamellar). Inner shell layer: aragonite (complex cross-lamellar).

  • Genus GRAMMATODON Meek & Hayden, 1860, p. 419

  • Type species.—Arca (Cucullaea) inornata Meek & Hayden, 1859, p. 51.

  • Remarks.—We regard Cosmetodon Branson, 1942, p. 248, as a subgenus of Grammatodon, following most authors (Fürsich, 1982; Kelly, 1984; Yancey, 1985; Damborenea, 1987a; Gardner & Campbell, 1997; Ivimey-Cook & others, 1999; Hautmann, 2001b; Nakazawa, 2002; Delvene, 2003). Some authors (Tashiro, 1986; Stiller, 2006) argued that Cosmetodon is a separate genus. Two other subgenera are included in our study range: Grammatodon and Indogrammatodon Cox, 1937b.

  • Stratigraphic range.—lower Permian (Artinskian)—Upper Cretaceous (Maastrichtian) (Yancey, 1985; Carter, 1990a). Newell in Cox and others (1969) included all Paleozoic members of the family Parallelodontidae within Parallelodon, but as stated above, there are certain specimens that should be attributed to Grammatodon instead (Manceñido, González, & Damborenea, 1976; Yancey, 1985). In the absence of a good review of Paleozoic members of this family, the first appearance is from the Permian Pacific margin (Manceñido, González, & Damborenea, 1976; Yancey, 1985) and the last appearance is from Upper Cretaceous age (Carter, 1990a). Sepkoski (2002) assigned it a Jurassic (Hettangian)—Cretaceous (?Cenomanian) range, following Cox and others (1969) and Hallam (1977).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 8).

  • Tethys domain; late Permian: Malaysia (Nakazawa, 2002), Greece (Clapham & Bottjer, 2007); Middle Triassic: Anisian of Malaysia (Tamura & others, 1975); Late Triassic; Carnian of Malaysia (Tamura & others, 1975); Norian of Iran (Repin, 2001); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Burma (Healey, 1908), northeastern England (Penarth Group) (Ivimey-Cook & others, 1999), Tibet (Hautmann & others, 2005), Austria (Tomašových, 2006a); Early Jurassic: Tibet (Gou, 2003); Hettangian of Tibet (Hautmann & others, 2005); Sinemurian of Vietnam (Hayami, 1964; Sato & Westermann, 1991), Portugal and southern England (Liu, 1995), China (Stiller, 2006).

  • Circumpacific domain: Early Jurassic: western United States (Oregon) (Fraser, Bottjer, & Fischer, 2004); Hettangian of Japan (Hayami, 1958d); Hettangian—Sinemurian of Japan (Hayami, 1975); Sinemurian of Chile (Aberhan, 1994a) and Canada (Aberhan, 1998a).

  • Austral domain: Middle Triassic: Ladinian of New Zealand (Marwick, 1953); Early Jurassic: Argentina (Damborenea, 1987a; Damborenea & Lanés, 2007); Hettangian—Sinemurian of Neuquén Basin (Damborenea & Manceñido, 2005b).

  • Boreal domain: late Permian: Norway (Nakazawa, 1999); Early Jurassic: Hettangian of Greenland (Liu, 1995).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The assignation of one specific mode of life to this genus is difficult. Duff (1978) and Damborenea (1987a) found several inconsistencies, depending on which features of the shell were observed. According to authors and species, Grammatodon was interpreted as epibyssate (Fürsich, 1982; Fürsich & others, 2001; Hautmann, 2001b; Delvene, 2003; J. Yin & Grant-Mackie, 2005; Aberhan, Kiessling & Fürsich, 2006; Stiller, 2006; Tomašových, 2006a), semi-infaunal (Fürsich, 1982; Pugaczewska, 1986; Delvene, 2003) or infaunal (Duff, 1978; Damborenea, 1987a; Gardner & Campbell, 1997; Harries & Little, 1999). According to S. M. Stanley (1972), the members of the subfamily Grammatodontinae would be rather epibyssate as suggested by their elongated shell by comparison with living species. However, in the same genus, we find species (such as G. toyorensis Hayami, 1959) with dorsally inflated shells and no evidence of byssal gape, which could be interpreted as shallow burrowers (Damborenea, 1987a); others [such as G. (Cosmetodon) mediodepressum (Krumbeck, 1913)] with an elongated ventral margin, which were probably epibyssate (Hautmann, 2001b), and finally, others [such as G. (Cosmetodon) keyserlingii (d'Orbigny, 1850) or G. (C.) marshallensis (Winchell, 1862)] showing a modioliform shape with an expanded posterior part, which are interpreted as semi-infaunal (S. M. Stanley, 1972; Fürsich, 1982). Having said that, we assign the prevailing inferred mode of life, i.e., epibyssate, to the genus.

  • Mineralogy.—Aragonitic (Carter, 1990b, p. 326). Outer shell layer: aragonite (cross-lamellar). Middle shell layer: aragonite (?). Inner shell layer: aragonite (cross-lamellar).

  • Genus BAPRISTODIA Guo, 1988, p. 115

  • Type species.—Bapristodia serrata Guo, 1988, p. 116.

  • Stratigraphic range.—Upper Triassic (Norian) (Guo, 1988). Guo (1988) proposed Bapristodia, a monospecific genus, from the Maichuqing formation dated as Norian (H. Yao & others, 2007).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 8).

  • Tethys domain: Late Triassic: Norian of southwestern China (Yunan) (Guo, 1988).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. We assign it the most common mode of life in the family Parallelodontidae. The external morphology of B. serrata is similar to some epibyssate species of Grammatodon, although no evidence of byssal gape is mentioned in the diagnosis offered by Guo (1988) [translated English version in Z. Fang & others, 2009].

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 184–185). There are no data about the shell mineralogy or microstructure of Bapristodia. Data provided for superfamily Arcoidea (Carter, 1990a).

  • Family CUCULLAEIDAE Stewart, 1930
    Genus CUCULLAEA Lamarck, 1801, p. 116

  • Type species.—Cucullaea auriculifera Lamarck, 1801, p. 116.

  • Remarks.—One of the subgenera of Cucullaea lived during the study interval: Idonearca Conrad, 1862, p. 289 (type species, Cucullaea tippana Conrad, 1858, p. 328).

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Holocene (Hayami, 1958d; Beesley, Ross, & Wells, 1998). Cucullaea had its origin during the Early Jurassic and reached its greatest diversity during the Late Cretaceous, followed by a gradual decline until the present. Although Cox and others (1969) assigned it a discontinuous range [Jurassic (Liassic)—Cretaceous, Holocene], Cucullaea was present during the Cenozoic (Griffin, 1991; Griffin & Nielsen, 2008). The oldest record is from the Hettangian (Hayami, 1958d, 1975). It is currently represented by a single species, C. labiata (Lightfoot, 1786), with an Indo-Pacific distribution (Beesley, Ross, & Wells, 1998).

  • Paleogeographic distribution.—Circumpacific (Fig. 9). Although during other times this genus was widely distributed, during the Early Jurassic (Hettangian and Sinemurian), it was only found in northwestern Pacific. During the Pliensbachian and Toarcian, it was distributed in the Arctic region (Zakharov & others, 2006), South America (A. F. Leanza, 1940, 1942; Damborenea, 1987a; Aberhan, 1994a), and Europe (Fürsich & others, 2001; Gahr, 2002).

  • Circumpacific domain: Early Jurassic; Hettangian of Japan (Hayami, 1958d, 1975).

  • Paleoautoecology.—B, Is-Se, S, SM; Sb. The species referred to Cucullaea have a very inflated quadrangular shell, with a truncated posterior end, indicative of a slow shallow-burrowing mode of life, as in modern species of Anadara (S. M. Stanley, 1970). The only extant species, C. labiata, lives at depths down to 200 m, buried in sand, with the anterior part downward (Beesley, Ross, & Wells, 1998). Damborenea (1987a) noted that shells of C. jaworskii A. F. Leanza and C. rothi A. F. Leanza (Lower Jurassic) lack epizoan organisms, whereas other epifaunal invertebrates from the same beds bear abundant epifauna. Thus we regard Cucullaea as a shallow infaunal or even semi-infaunal bivalve (see Damborenea, 1987a, p. 75).

  • Mineralogy.—Aragonitic (Carter, 1990b, p. 326). Outer shell layer: aragonite (prismatic or cross-lamellar). Middle shell layer: aragonite (cross-lamellar). Inner shell layer: aragonite (complex cross-lamellar).

  • Superfamily LIMOPSOIDEA Dall, 1895
    Family PHILOBRYIDAE Bernard, 1897
    Genus EOPHILOBRYOIDELLA Stiller & Chen, 2004, p. 414

  • Type species.—Eophilobryoidella sinoanisica Stiller & Chen, 2004, p. 414.

  • Stratigraphic range.—Middle Triassic (upper Anisian) (Stiller & Chen, 2004). Eophilobryoidella is particularly abundant in the middle part of the Leidapo Member of Qingyan formation. Up to now, the family Philobryidae was believed to range from the Eocene to the present time, but this finding extends its stratigraphic range back to the Middle Triassic. Therefore, the idea that this family evolved from the family Limopsidae, which has a Cretaceous origin, is invalidated (Stiller & Chen, 2004; Oliver & Holmes, 2006).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 9).

  • Tethys domain: Middle Triassic: late Anisian of southwestern China (Guizhou province) (Stiller & Chen, 2004).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Living members of family Philobryidae are suspensivorous and live at depths that can exceed 1000 m, almost always attached (epibyssate) to other organisms (Beesley, Ross, & Wells, 1998). Stiller and Chen (2004) interpreted that Eophilobryoidella had a similar mode of life, although a byssal notch is not observed. These authors suggested that species of this genus were epibyssate, because they found epizoan organisms attached to the shells while the bivalve was alive. According to the environment in which these organisms lived, they concluded the species of Eophilobryoidella preferred shallow, low energy and normal salinity waters.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 195; Carter, 1990b, p. 328). There is no information about Eophilobryoidella shell mineralogy or microstructure. Data from Recent Philobryidae specimens are used. Outer shell layer: aragonite (?). Middle shell layer: aragonite (cross-lamellar). Inner shell layer: aragonite (complex cross-lamellar).

  • Figure 9.

    Paleogeographical distribution of Cucullaeidae (Cucullaea) and Philobryidae (Eophilobryoidella). 1, Middle Triassic; 2, Early Jurassic.

    f09_01.jpg

    Family PICHLERIIDAE Scarlato & Starobogatov, 1979
    Genus HOFERIA Bittner, 1894, p. 190

  • Type species.—Lucina duplicata Münster, 1841, in Goldfuss, 1833–1841, p. 227.

  • Stratigraphic range.—Upper Triassic (Carnian). There are some Hoferia records from the Ladinian (Hallam, 1981; Kobayashi & Tamura, 1983a; Sepkoski, 2002), but none of these figure or indicate the original source of the data, and all of them are referred to the Alps. Hoferia was listed from the Cassian Formation in the southern Alps; according to Fürsich and Wendt (1977, fig. 2), this unit is upper Anisian to the lower part of the upper Carnian in age. Nevertheless, Fürsich (in PBDB, 2005) provided data from this paper, and he clearly assigned a Carnian age to Hoferia specimens. In addition, Kobayashi and Tamura (1983a) also mentioned Hoferia from the Norian of Yunnan, but they did not provide any bibliographic reference. The only quotation of this genus from Yunnan is Cowper-Reed (1927), but from the Carnian. The last author only had a badly preserved internal mold of a right valve, and he included the specimen in Hoferia, because it shows a characteristic anterior lobe. We assign here a Carnian range to Hoferia.

  • Paleogeographic distribution.—Tethys (Fig. 10).

  • Tethys domain: Late Triassic: Carnian of the Italian Alps (Leonardi, 1943; Fürsich & Wendt, 1977), Yunnan (China) (Cowper-Reed, 1927).

  • Paleoautoecology.—B, Is, S, Endo, SM; Sb. The family Pichleriidae includes members of both shallow burrowers and those with epibyssate attached. Hoferia presents a byssal groove (see diagnosis in Cox & others, 1969, p. 265), and thus it must have been byssate. The globose shell suggests it was an endobyssate shallow burrower that lived near the surface or even semi-infaunally.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 196). There are no specific data for Hoferia, but we provisionally use those provided by Carter (1990a) for the family Pichleriidae, provided by the analysis of Pichleria, a genus closely related to Hoferia (see above).

  • Figure 10.

    Paleogeographical distribution of Pichleriidae (Hoferia, Pichleria, Elegantarca). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f10_01.jpg

    Genus PICHLERIA Bittner, 1894, p. 189

  • Type species.—Cucullaea auingeri Laube, 1865, p. 62.

  • Stratigraphic range.—Upper Triassic (Carnian) (Cox & others, 1969). Cox and others (1969) assigned Pichleria to the Upper Triassic, and Sepkoski (2002) to the Triassic (upper Ladinian—Carnian), following Hallam (1981) (see discussion for Hoferia). Wen and others (1976) mentioned Pichleria from the Norian of China, but the figured specimens (pl. 7,6–13) are members of family Limidae.

  • Paleogeographic distribution.—Tethys (Fig. 10).

  • Tethys domain: Late Triassic: Carnian of southern Alps (Italy) (Bittner, 1894, 1895; Diener, 1923; Leonardi, 1943; Corazzari & Lucchi-Garavello, 1980), southern Tunisia (Desio, Rossi Ronchetti, & Vigano, 1960).

  • Paleoautoecology.—B, Is-Se, S, Sed; ?. The shell morphology indicates that Pichleria probably lived semi-infaunally or infaunally near the substrate surface. Byssal notch and sinus appear to be absent.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 196). Outer shell layer: aragonite (prismatic). Middle shell layer: aragonite (nacreous). Inner shell layer: aragonite (prismatic).

  • Genus ELEGANTARCA Tomlin, 1930, p. 23

  • Type species.—Arcoptera elegantula Bittner, 1895, p. 126.

  • Remarks.—Cox and others (1969) regarded Elegantarca (nom. nov. pro Arcoptera Bittner, 1895, p. 126, non Heilprin, 1887, p. 98) as a synonym of Hoferia, but Stiller (personal communication, 2005) argued to maintain them as separate genera, due to differences in orientation, number, and shape of the hinge teeth and other morphological disparities. In his own words: “Elegantarca shows some distinct morphological differences to Hoferia. Outer shell shape: Elegantarca has a large posterodorsal wing separated from the body of shell by a distinct but generally blunt posterior umbonal ridge (this diagonal ridge is lacking in Hoferia); Elegantarca in many cases is distinctly produced posteroventrally, Hoferia generally is shorter and more rounded. However, more important are differences in the hinge structure: Hoferia has a hinge with at least 10 short, taxodont teeth, which are radially arranged in two groups (Bittner, 1895; Broili, 1904; Cox & others, 1969); Elegantarca has very few, strong, radial teeth below the umbo, and one anterior and one posterior elongated tooth (about parallel to the hinge margin) (Broili 1904). The Chinese Elegantarca subareata Chen, Ma, & Zhang, 1974 has a hinge like the bivalves figured by Broili (1904, Arcoptera).”

  • Vokes (1980) regarded Bittnerella Dall, 1898, p. 613 (nom. nov. pro Arcoptera Bittner, 1895) as a valid name with priority over Elegantarca, but Bittnerella was included in the synonymy of Hoferia by Cox and others (1969), and now the name Bittnerella Dagys, 1974, p. 77, is used for a brachiopod genus.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Bittner, 1895; Komatsu, Chen, & others, 2004). The oldest known record of Elegantarca dates from Anisian times (Komatsu, Chen, & others, 2004; Stiller, personal communication, 2005) and the youngest from the Carnian (Bittner, 1895).

  • Paleogeographic distribution.—Tethys (Fig. 10).

  • Tethys domain: Middle Triassic: Anisian of southern China (Anonymous, 1974; Komatsu, Chen, & others, 2004; Stiller, personal communication, 2005), Bosnia (Diener, 1923); Ladinian of southern Alps (Italy) (Diener, 1923); Late Triassic: Carnian of southern Alps (Italy) (Bittner, 1895; Broili, 1904; Waagen, 1907).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. See Hoferia. Komatsu, Chen, and others (2004) regarded it as endobyssate semi-infaunal.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 196). See Hoferia.

  • Superfamily AMBONYCHIOIDEA Miller, 1877
    Family MYALINIDAE Frech, 1891
    Genus MYALINA de Koninck, 1842 in 1841–1844, p.125

  • Type species.—Myalina goldfussiana de Koninck, 1842 in 1841– 1844, p. 126.

  • Stratigraphic range.—Carboniferous (lower Mississippian)—upper Permian, ?Lower Triassic (McRoberts, personal communication, 2005). Both Cox and others (1969) and Sepkoski (2002) assigned a Carboniferous (Lower Mississippian)—upper Permian range to this genus, but previously and subsequently, several authors mentioned Myalina from the Lower Triassic (e.g., Kiparisova, 1938; Newell & Kummel, 1942; Ciriacks, 1963; Dagys & Kurushin, 1985; Schubert, 1993; Schubert & Bottjer, 1995; McRoberts & Newell, 2005). All these references are better regarded as belonging to Promyalina, Myalinella, or even Promytilus (McRoberts, personal communication, 2005; McRoberts, 2005). So we leave the Triassic record of this genus as doubtful pending a good review of the problem. According to McRoberts (personal communication, 2005), no myalinid reached the Middle Triassic, since the only genus mentioned for that age (Aviculomyalina) should in fact be included in the Pteriidae or Malleidae.

  • Paleogeographic distribution.—Circumpacific (Fig. 11). Myalina had a cosmopolitan distribution, but from the late Permian, we only find records from the Tethys and Circumpacific domains. The family Myalinidae had significant diversity and abundance during the Carboniferous and Permian, but at the Permian—Triassic extinction, this family was decimated, later to disappear by the end of the Early Triassic (McRoberts, 2005). The doubtful Early Triassic records belong to the Circumpacific and Boreal domains.

  • Circumpacific domain: late Permian: western United States (Newell, 1942; Walter, 1953; McRoberts & Newell, 2005), Japan (Nakazawa & Newell, 1968; Hayami & Kase, 1977).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Species attributed to this genus have different morphologies and, consequently, their mode of life can be semi-infaunal (endobyssate) to epifaunal (epibyssate) (S. M. Stanley, 1972, fig. 12). Upper Permian specimens have reduced anterior lobes and, in some cases, bear a byssal sinus (M. lamellosa McRoberts & Newell, 2005; M. plicata McRoberts & Newell, 2005; M. copei Whitfield, 1902; see diagnosis in McRoberts & Newell, 2005), characters that indicate a byssate mode of life. Nevertheless, their thick and heavy shells were probably not functional for byssus attachment, and they were not active (Newell, 1942). According to McRoberts and Newell (2005), M. lamellosa probably lived lying on its anterior side, with an almost vertical commissure, lightly resting on its left valve. The species had a gregarious mode of life and is found in groups, as are many Recent mussels (Newell, 1942). Substrate type should also be taken into account: in soft substrates, they commonly adopt an endobyssate mode of life to become stable, while on hard substrates, they were frequently epibyssate.

  • Mineralogy.—Bimineralic (Newell, 1942, p. 33–34; Carter, 1990b, p. 331). Outer shell layer: calcite (prismatic-homogeneous). Inner shell layer: aragonite (nacreous).

  • Genus MYALINELLA Newell, 1942, 60

  • Type species.—Myalina meeki Dunbar, 1924, p. 201.

  • Remarks.—Newell (1942) described Myalinella as a subgenus of Myalina, pointing out the differences between Myalinella and other myalinids, such as Myalina (Myalina). Later, the same author (in Cox & others, 1969), raised Myalinella to genus level.

  • Stratigraphic range.—Carboniferous (Visean)—Lower Triassic (upper Olenekian) (R. Zhang & Pojeta, 1986; Fraiser & Bottjer, 2007a). Newell in Cox and others (1969) assigned a Carboniferous (Pennsylvanian)—Lower Triassic range to this genus and recorded it from Europe, United States, India, and Greenland. However, R. Zhang and Pojeta (1986) reported the first record of Myalinella from the Visean of China. The youngest record is Olenekian (Newell, 1942; Schubert, 1993; Schubert & Bottjer, 1995; Fraiser & Bottjer, 2007a).

  • Paleogeographic distribution.—Tethys, Boreal, and Circumpacific (Fig. 11). Myalinella had a wide distribution, but, during the late Permian, it seems restricted to few records; for instance, it was extensively mentioned from the western coast of the United States from the Permian until Guadalupian times (e.g., Newell, 1942; Ciriacks, 1963), but, from then on, it is only recorded from the Lower Triassic (e.g., Schubert, 1993), possibly due to lack of upper Permian deposits in this area. Even though during the early Permian it was present in the Tethys (e.g., Zheng, 1993), it seems to have been absent from this domain during the late Permian. However, it was recently reported from the Lower Triassic (Hautmann & others, 2011). Fraiser and Bottjer (2007a) studied several Lower Triassic sections from Japan and Italy, and they did not report Myalinella, but they did find another genus of the same family (Promyalina).

  • Tethys domain: Early Triassic: Induan of southern China (Hautmann & others, 2011).

  • Boreal domain: Early Triassic: Greenland (Newell, 1942).

  • Circumpacific domain: Early Triassic: United States (Schubert, 1993; Schubert & Bottjer, 1995; Fraiser & Bottjer, 2007a).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Specimens of this genus are usually found with closed valves, suggesting that they lived in low energy areas and/or were buried (Newell, 1942). They tolerated a wide salinity range (Newell, 1942), and they were found in fully marine (Kues, 2004) to estuarine environments (Mack & others, 2003). The shell shows some features indicative of a probable endobyssate and semi-infaunal mode of life: they have an anterior lobe and a byssal sinus, and their shells are small and fragile (Newell, 1942; McRoberts & Newell, 2005).

  • Mineralogy.—Bimineralic (Newell, 1942, p. 33–34). There are no available data about Myalinella shell microstructure. Newell (1942) indicated that, unlike most myalinids, Myalinella exhibits the same structure in both valves. We assign the type present in members of the family Myalinidae.

  • Figure 11.

    Paleogeographical distribution of Myalinidae (Myalina, Myalinella, Promyalina, Aviculomyalina). 1, late Permian—Early Triassic; 2, Middle Triassic.

    f11_01.jpg

    Genus PROMYALINA Kittl, 1904, p. 690

  • Type species.—Promyalina hindi Kittl, 1904, p. 690.

  • Stratigraphic range.—upper Permian (upper Changhsingian)—Lower Triassic (upper Olenekian) (Fraiser & Bottjer, 2007a; He, Feng, & others, 2007). Cox and others (1969) assigned a Lower Triassic range to this genus, and they also doubtfully considered its presence in upper Permian beds. Although some authors (Sepkoski, 2002; McRoberts, 2005; McRoberts & Newell, 2005) only took into account the Lower Triassic records, others (Farabegoli, Perri, & Posenato, 2007, fig. 7; He, Feng, & others, 2007, fig. 5.18) accepted the late Permian records (late Changhsingian) from the Tethys domain. Promyalina showed a maximum abundance at the beginning of the Early Triassic, and it went extinct at the end of the same epoch.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 11).

  • Tethys domain: late Permian: Italy (Farabegoli, Perri, & Posenato, 2007), Changhsingian of southern China (He, Feng, & others, 2007); Early Triassic: China (Z. Yang & Yin, 1979; C. Chen, 1982; F. Wu, 1985; Lu & Chen, 1986; Ling, 1988; Komatsu, Huyen, & Chen, 2006, 2007), northern Vietnam (Komatsu, Huyen, & Chen, 2006, 2007); Induan of Oman (Krystyn & others, 2003; Twitchett & others, 2004), south of China (Hautmann & others, 2011); Induan—early Olenekian of Italy (Broglio-Loriga & others, 1990; Fraiser & Bottjer, 2005a, 2007a; Posenato, 2008a).

  • Circumpacific domain: Early Triassic: early Olenekian of Japan (Nakazawa, 1961; Hayami, 1975; Fraiser & Bottjer, 2007a); Olenekian of western United States (Ciriacks, 1963; Boyd, Nice, & Newell, 1999; Boyer, Bottjer, & Droser, 2004; Fraiser & Bottjer, 2007a).

  • Boreal domain: Early Triassic: northern Siberia (Dagys & Kurushin, 1985); Induan of Greenland (Wignall, Morante, & Newton, 1998; Wignall & Twitchett, 2002).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Promyalina was one of the more widely distributed genera during the Early Triassic worldwide. Together with Eumorphotis and Unionites, it dominated the bivalve fauna of the seas at the beginning of the Triassic (Fraiser & Bottjer, 2005b, 2007a). It showed a typical opportunistic behavior, being more abundant when conditions were adverse but disappearing as soon as environmental conditions were restored, probably by competition with more specialized taxa. Morphological characteristics indicate a probable semi-infaunal and endobyssate mode of life, similar to Myalina (Schubert, 1993). Posenato (2008a) suggested an epibyssate mode of life.

  • Mineralogy.—Bimineralic (McRoberts & Newell, 2005). No data are available for shell mineralogy or microstructure of the species of this genus. We use data for the family Myalinidae (see McRoberts & Newell, 2005). Outer shell layer: calcite (prismatic-homogeneous). Inner shell layer: aragonite (nacreous).

  • Figure 12.

    Paleogeographical distribution of Inoceramidae (“Parainoceramus,“ Pseudomytiloides, Arctomytiloides). Late Triassic—Early Jurassic.

    f12_01.jpg

    Genus AVICULOMYALINA Assmann, 1916, p. 608

  • Type species.—Aviculomyalina lata Assmann, 1916, p. 608.

  • Remarks.—Both McRoberts (2005) and Waller (in Waller & Stanley, 2005) pointed out that Aviculomyalina could be better located within the Pteriidae or Malleidae. We keep it in Myalinidae until this matter is adequately discussed.

  • Stratigraphic range.—Middle Triassic (Anisian) (Cox & others, 1969). Assmann (1916) described the genus from the Lower Muschelkalk (probably Anisian), in the “Erzführender Dolomit” Formation of Silesia. Other authors also reported it from Anisian beds (Malinowskiej, 1979; Sepkoski, 2002). The range of this genus could be extended to Carnian and Norian if Aviculomyalina? williamsi (McLearn, 1941) were considered to belong to this genus, as proposed by Waller (in Waller & Stanley, 2005), rather than to Mysidioptera as proposed by Newton (in Newton & others, 1987).

  • Paleogeographic distribution.—Tethys (Fig. 11).

  • Tethys domain: Middle Triassic: Anisian of Poland (Assmann, 1916; Malinowskiej, 1979), Alps (?Switzerland) (Zorn, 1971).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. An epibyssate mode of life is suggested by some shell features, such as the external shell morphology, the presence of byssal gape, and the flattened anterior margin (Newton in Newton & others, 1987).

  • Mineralogy.—Bimineralic. There is no information about Aviculomyalina shell mineralogy or microstructure, but we regard it equivalent to Promyalina.

  • Family INOCERAMIDAE Giebel, 1852

  • The family Inoceramidae is especially problematic, due partly to its great morphological variability, and partly to the lack of consensus among specialists about the taxonomically significant characters. It is often difficult to discern between the different genera assigned to this family because, if internal characters are not shown, the external shape is extremely variable, even within species (Crame, 1982). This is the consequence of convergent evolution resulting from functional and ecological constraints, the presence of few easily distinguishable characters, the great variability within species, and also the high evolutionary rates they exhibit. As a result, the group has a rich fossil record with a long history but with the serious drawback of a wide disparity of concepts used by successive specialists (Harries & Crampton, 1998).

  • Genus “PARAINOCERAMUS“ Cox, 1954, p. 47

  • ex Voronetz, 1936, p. 23, 34, nom. nud.

  • Type species.—Parainoceramus bulkuriensis Voronetz, 1936, p. 24, 34.

  • Remarks.—The generic name Parainoceramus was proposed by Voronetz (1936, p. 23, 34) on the basis of badly preserved specimens from sediments then dated as Carnian from northern Siberia. The author included four species in this new genus, but he did not designate a type, and thus this name was not available. Years later, Cox (1954) completed the requirements for the validity of the name by designating P. bulkurensis Voronetz as the type (ICZN, 1999, Art. 13B, 50). He did not see Voronetz's material, but, nevertheless, he included within Parainoceramus two other species that are widely distributed in the European Jurassic: “Crenatulaventricosa J. de C. Sowerby, 1823, and Inoceramus substriatus Münster, 1835, in Goldfuss, 1833–1841. On the basis of his knowledge of these last species, he emended Voronetz's original diagnosis to include an anterior auricle and anterior teeth on some species. Cox's (1954) concept of the genus Parainoceramus was followed by nearly all later authors dealing with Jurassic material (e.g., Hayami, 1960; Speden, 1970; Duff, 1978; Damborenea, 1987b; J. Chen, 1988; M. A. Conti & Monari, 1991; Monari, 1994), who added more Jurassic species from around the world. Nevertheless, it is all too evident that this was reluctantly done in many instances, in the absence of a better alternative. Another point overlooked in the Treatise (Cox & others, 1969, p. 320) and by later authors is that Emel'yantsev and others (1960; see also Muromtseva, 1979; and Astafieva, 1986) had redated the beds where Voronetz's original material was found to be upper Permian (Wuchiapingian and Changhsingian), and thus the stratigraphic range of Parainoceramus sensu Cox (1954) should be upper Permian (Siberia), Hettangian to Tithonian (cosmopolitan), with no record during the Triassic. A breakthrough was provided by Astafieva (1986, 1993), who revised Voronetz's original material and concluded that the type species should be referred to the Paleozoic genus Kolymia Licharew in Licharew & Einor, 1941. Thus, several widely distributed and common Jurassic species (Parainoceramus sensu Cox non Voronetz) remain without a genus to be referred to. We will provisionally use here the name “Parainoceramus” in this sense, until a proper solution is developed (Ros, Damborenea, & Márquez-Aliaga, 2009), and we record its first appearance in the earliest Jurassic. When the material is not well preserved, it is difficult to distinguish between Parainoceramus in this sense and Pseudomytiloides Koschelkina, 1963 (Aberhan, 1998a; Stiller, 2006).

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Upper Jurassic (Tithonian) (Escobar, 1980; Kelly, 1984). Both Cox and others (1969) and Sepkoski (2002) regarded the first appearance of “Parainoceramus“ to be Upper Triassic following Voronetz (1936), ignoring that Emel'yantsev, Kravtsova, and Puk (1960) had already corrected the dating of the beds from which Voronetz described his specimens from Carnian to upper Permian. We assign the Lower Jurassic (Hettangian) as the oldest record (Escobar, 1980; Damborenea, 1996a), taking into account only the species assigned to this genus sensu Cox (1954). The youngest record is from the Tithonian (Kelly, 1984; Fozy, Kázmér, & Szente, 1994; Liu, 1995).

  • Paleogeographic distribution.—Tethys, Boreal, and Circumpacific (Fig. 12). “Parainoceramus” was cosmopolitan during the Early Jurassic (especially during the Pliensbachian), but during the Middle and Late Jurassic, it appears to have had a bipolar distribution (possibly Boreal and Austral domains) (Damborenea, 1996b). For further information, see Damborenea (1987b, p. 142–146).

  • Tethys domain: Early Jurassic: Tibet (Gou, 1985), China (J. Chen, 1982a, 1988); Hettangian of Vietnam (Hayami, 1964); Hettangian—Sinemurian of China (Stiller, 2006); Sinemurian of southern England (Liu, 1995), Turkey (M. A. Conti & Monari, 1991), China (Y. Wang & Smith, 1986).

  • Boreal domain: Early Jurassic: Sinemurian of northern Siberia (Hallam, 1977).

  • Circumpacific domain: Early Jurassic: Japan (Hayami, 1960); Hettangian—Sinemurian of Canada (Aberhan, 1998a); Hettangian of Chile (Escobar, 1980).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The shell morphology of species attributed to “Parainoceramus“ is variable, and it largely depends on the type of environment. Some species, such as “P.” jinjiensis Chen, 1988, or “Psubtilis (Lahusen), are mytiliform, and they were probably epibyssate (Duff, 1978; Stiller, 2006), but other species, such as “P.” apollo (A. F. Leanza, 1942), are modioliform with a well-developed anterior lobe, and they possibly had an endobenthic mode of life (Damborenea, 1987b). Other genera of the same family, such as Pseudomytiloides, were interpreted as pseudoplanktonic, at least in the early stages (Hayami, 1969a; Etter, 1996). “Parainoceramus” species are found in a wide array of facies types, since they could inhabit different environments, but they are especially abundant in anoxic facies (black shales) (Damborenea 1987b; Harries & others, 1996).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 200; Carter, 1990b, p. 330). Outer shell layer: calcite (prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus PSEUDOMYTILOIDES Koschelkina, 1963, p. 129

  • Type species.—Mytiloides marchaensis Petrova, 1947, p. 130.

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Middle Jurassic (Aalenian) (Etter, 1996; Stiller, 2006). Cox and others (1969) assigned a Jurassic range to this genus. The oldest record is from Hettangian deposits (Stiller, 2006) and the youngest from Aalenian beds (Etter, 1996). The genus was also mentioned from the Upper Triassic (Norian—Rhaetian) of northeastern Asia (Kurushin, 1990; Polubotko & Repin, 1990), but without indication of the original sources and with no illustrations, so these records remain doubtful.

  • Paleogeographic distribution.—Tethys (Fig. 12). This genus was especially abundant during the Toarcian. During the earliest Jurassic, it was only reported from the Tethys; but it was also recorded from the Boreal domain by Pliensbachian and Toarcian times (Zakharov & others, 2006). Poulton (1991) reported Pseudomytiloides (?) sp. from ?Hettangian beds of Canada, but it was only one specimen questionably referred to this genus.

  • Tethys domain: Early Jurassic: Hettangian—Sinemurian of China (Stiller, 2006); Sinemurian of southwestern France (Liu, 1995).

  • Paleoautoecology.—B-Ps, E, S, Epi, Sed-FaM; By. Pseudomytiloides dubius (J. de C. Sowerby, 1823) is particularly linked to the black shale facies, associated with anoxic conditions, since its abundance decreases as soon as the normal environmental conditions are restored after the early Toarcian extinction event (Harries & Little, 1999; Fürsich & others, 2001; Caswell, Coe, & Cohen, 2009). A pseudoplanktonic mode of life was proposed for this species and P. matsumotoi (Hayami, 1960) (Hayami, 1969a; Tanabe 1983; Seilacher, 1990). This was based on many forms of evidence: they are often found in anoxic facies (Hayami, 1969a), attached to pieces of wood (Hayami, 1969a; Tanabe 1983; Seilacher, 1990), and to ammonoid shells and other bivalves (Tanabe, 1983). However, some authors (e.g., Wignall & Simms, 1990; Etter, 1996) suggested that this interpretation is inadequate since the species abundance is too high to be derived only from floating logs. They proposed that P. dubius had a benthic epibyssate mode of life instead, but it could occasionally live as facultative pseudoplanktonic, with the capacity to attach to various substrates, such as floating objects, and tolerate low oxygen environments (see also Caswell, Coe, & Cohen, 2009). Some authors proposed that certain species of Pseudomytiloides might contain chemosymbionts that would help them live in these inhospitable settings (Harries & Crampton, 1998). Other species, such as P. yinhangensis Chen, 1988, were found in well-oxygenated, quiet, and near-shore environments (Stiller, 2006). The epibyssate mode of life is clearly suggested by their mytiliform shells and their long and flat anteroventral margin (Tanabe, 1983).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 200). There are no specific data for Pseudomytiloides. Data used here provided by Carter (1990a) for family Inoceramidae. Outer shell layer: calcite (prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus ARCTOMYTILOIDES Polubotko, 1992, p. 64

  • Type species.—Pseudomytiloides rassochaensis Polubotko, 1968b, p. 61.

  • Stratigraphic range.—Lower Jurassic (Sinemurian—?Toarcian) (Aberhan, 1998a). The genus was described by Polubotko (1992). It was reported from the Sinemurian of northeastern Russia, and it includes the following species besides the type: A. sinuosus (Polubotko, 1968b), A. kelimiarensis Polubotko, 1992, and A. (?) turomtchensis Polubotko, 1992. Subsequently, Aberhan (1998a) doubtfully reported it from Toarcian beds.

  • Paleogeographic distribution.—Boreal and Circumpacific (Fig. 12).

  • Boreal domain: Early Jurassic: Sinemurian of northeastern Russia (Polubotko, 1968b, 1992).

  • Circumpacific domain: Early Jurassic: Sinemurian—Toarcian of ?Canada (Aberhan, 1998a).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Its mytiliform shell indicates an epibyssate mode of life, similar to some living species of the family Mytilidae.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 200). No data about Arctomytiloides shell mineralogy and microstructure are available. Data provided for the family Inoceramidae (see any genera in this family).

  • Superfamily PTERIOIDEA Gray, 1847
    Family PTERIIDAE Gray, 1847
    Genus PTERIA Scopoli, 1777, p. 397

  • Type species.—Mytilus hirundo Linnaeus, 1758, p. 706.

  • Remarks.—Pteroperna Morris & Lycett, 1853 in 1851–1855, is a subgenus, and Rhynchopterus Gabb, 1864, is a junior synonym of Pteria s.l. (see discussion for Pteroperna and Rhynchopterus in Genera not Included, p. 169 and 170).

  • Stratigraphic range.—Lower Triassic (Olenekian)—Holocene (Hayami, 1975; Beesley, Ross, & Wells, 1998). Pteria ranges from Triassic to Holocene times (Cox & others, 1969; Sepkoski, 2002). The earliest record found is P. ussurica (Kiparisova, 1938) from the Induan (Hayami, 1975). There are some pre-Triassic records (see PBDB, on-line), but most of them were published before Cox and others (1969). M. Wang (1993) described Pteria? yonganensis M. Wang, 1993, from upper Permian beds, but the generic assignment was only tentative, since he had few specimens and their differences with Pteria were important. Tëmkin (2006) doubted the origin of Pteria in the Early Triassic because many so-called winged shells that probably belong to other families (even Bakevelliidae or Isognomonidae) were referred to this genus.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 13). In the past, Pteria was a widespread genus; today it is common in warm seas (Cox & others, 1969; Beesley, Ross, & Wells, 1998), and was apparently not known from the Austral domain.

  • Tethys domain: Early Triassic: China (Z. Yang & Yin, 1979; S. Yang, Wang, & Hao, 1986; Ling, 1988; L. Li, 1995; Shen, He, & Shi, 1995; Tong & others, 2006; Komatsu, Huyen, & Chen, 2007); Middle Triassic: Anisian of the Alps (Switzerland) (Zorn, 1971), southern China (Komatsu, Chen, & others, 2004; Komatsu, Akasaki, & others, 2004); Anisian—Ladinian of northern Vietnam (Komatsu, Huyen, & Huu, 2010); Late Triassic: Carnian of Italy (Allasinaz, 1966; Fürsich & Wendt, 1977; Corazzari & Lucchi-Garavello, 1980), Germany (Linck, 1972); Norian of China (Lu, 1981); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Italy (Allasinaz, 1962; Gelati & Allasinaz, 1964; Gaetani, 1970); Early Jurassic: Hettangian of Italy (Allasinaz, 1962), China (J. Yin & McRoberts, 2006); Hettangian—Sinemurian of Italy (Gaetani, 1970); Sinemurian of eastern Asia (Hallam, 1977), Portugal (Liu, 1995).

  • Circumpacific domain: Early Triassic: Japan (Nakazawa, 1971; Hayami, 1975; Kashiyama & Oji, 2004); Late Triassic: Norian of Japan (Nakazawa, 1964); Early Jurassic: Hettangian of Japan (Hayami, 1975; Kondo & others, 2006; Fraiser & Bottjer, 2007a), ?Chile (Aberhan, 1994a).

  • Boreal domain: Late Triassic: Carnian of Primorie (Kiparisova, 1972).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Extant Pteria species often live attached to corals, usually by a strong byssus (S. M. Stanley, 1970, 1972). In many fossil specimens, the byssal notch is present (e.g., Damborenea, 1987b, Pteroperna sp.) and the shell morphology is similar enough to living species shells to assume they had a similar mode of life. They are often found forming groups of several individuals, probably as the result of a gregarious mode of life, as happens in modern species (S. M. Stanley, 1970).

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 336, for living species). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus ARCAVICULA Cox, 1964, p. 47

  • Type species.—Avicula arcuata Münster in Goldfuss, 1835 in 1833–1841, p. 128.

  • Stratigraphic range.—Lower Triassic (lower Olenekian)—Upper Triassic (?Rhaetian) (Sha & Grant-Mackie, 1996; Newton in Newton & others, 1987). Although many authors assigned it a Middle Triassic (Ladinian)—Upper Triassic (Carnian) range (Cox & others, 1969; Hallam, 1981; Sepkoski, 2002; Tëmkin, 2006), Arcavicula was also mentioned from the Lower Triassic (Sha & Grant-Mackie, 1996) and with some uncertainty from the Norian (Newton in Newton & others, 1987). Newton (in Newton & others, 1987) provisionally referred her specimens to Arcavicula sp. due to the hinge details, but she related them to Rhaetavicula on account of their external similarity. It is also evident that some species were attributed to Pteria regardless of their internal characters. Newton (1988) later confirmed this reference. Laws (1982) mentioned but did not figure Arcavicula sp. from Upper Triassic (upper Norian = Rhaetian, according to Dagys & Dagys, 1994) from Nevada. There are no specific Middle Triassic Arcavicula records, although several authors (e.g., Cox & others, 1969; Hallam, 1981; Sepkoski, 2002; Tëmkin, 2006) mentioned this genus among their materials.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 13).

  • Tethys domain: Early Triassic: early Olenekian of China (Sha & Grant-Mackie, 1996); Late Triassic: Carnian of southern Alps and Apennines (Italy) (Broglio-Loriga, Ietto, & Posenato, 1993), Alps and Sicily (Diener, 1923; Kutassy, 1931), early Carnian of Lombardy (Italy) (Allasinaz, 1966), southern Alps (Italy) (Bittner, 1895); Norian of ?China (Kobayashi & Tamura, 1983a).

  • Circumpacific domain: Late Triassic: Norian of Oregon (United States) (Newton & others, 1987; Newton, 1988); Rhaetian of ?Nevada (United States) (Laws, 1982).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The presence of anterior auricle and byssal sinus in some specimens, and their external morphology, indicate that species of this genus most likely lived epibyssate or shallowly buried in the sediment in the adult stage, by comparison with living Pterioida (Newton in Newton & others, 1987).

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 335). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus RHAETAVICULA Cox, 1962, p. 594

  • Type species.—Avicula contorta Portlock, 1843, p. 126.

  • Remarks.—Cox (1962) pointed out the similarities between Rhaetavicula and Oxytoma, and he proposed that Rhaetavicula could even be a member of the family Oxytomidae, but Rhaetavicula lacks the deep byssal groove located under the right anterior auricle, which is typical of that family. Based on the information provided by the shell mineralogy of Rhaetavicula (calcitic outer layer and alleged aragonitic inner layer), it is probably referable to Pteriidae. Nevertheless, if further studies confirm an inner calcitic layer, it should be referred to the Oxytomidae instead (Cox, 1962). There are no studies on this subject (Carter, 1990a). Previous to 1962, when Cox described this genus, the type species of Rhaetavicula was assigned to different genera: Avicula, Pseudomonotis, Cassianella, and Pteria.

  • Stratigraphic range.—Upper Triassic (Rhaetian). Rhaetavicula contorta is a Rhaetian guide fossil (see references in paleogeographic distribution). During that stage, it was widely distributed, especially in the Tethys domain.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 13). Though Rhaetavicula was reported from the Austral domain (New Zealand), Cox (1962, p. 594) referred this record to Oxytoma. Although Hallam (1981, 1990) also listed it from Austral regions, the record will not be taken into account here because this information could not be confirmed.

  • Tethys domain: Late Triassic: Rhaetian of England (Cox, 1962; Castell & Cox, 1975; Warrington & Ivimey-Cook, 1990; Ivimey-Cook & others, 1999; Wignall & Bond, 2008), Italy (Allasinaz, 1962; Sirna, 1968; Bice & others, 1992; McRoberts, 1994), Hungary (Vörös, 1981), Burma (Vu Khuc & Huyen, 1998), southern Tibet (Hallam & others, 2000; J. Yin & Enay, 2000), Iran (Hautmann, 2001b), western Carpathians (Slovakia) (Tomašových, 2004; Michalík & others, 2007), Alps (Austria) (Tomašových, 2006a, 2006b; McRoberts, 2010), Spain (Goy & Márquez-Aliaga, 1998).

  • Circumpacific domain: Late Triassic: Rhaetian of Nevada (United States) (Cox & others, 1969; Hallam & Wignall, 2000).

  • Paleoautoecology.—B, E, S, Epi-Un, Sed; By-R. According to Cox (1962), Rhaetavicula lacked a byssal notch, and he assumed that the byssus emerged between the two valves by a narrow gape. Since the shell is strongly inequivalve (convex left valve and flat right valve) and by similarities to living Pterioida, it probably had an epibyssate mode of life. Another possibility is that the byssus was atrophied in adults (and thus the byssal notch is absent), and then it would live reclined on its left valve, similar to members of the family Cassianellidae (Hautmann, 2001b).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206). Outer shell layer: calcite (prismatic). Middle and inner shell layers: aragonite (?).

  • Genus STEFANINIA Cox in Cox & others, 1969, p. 306
    [ex Venzo, 1934, p. 165]

  • Type species.—Gervilleia? ogilviae Bittner, 1895, p. 88.

  • Remarks.—Stefaninia was named by Venzo (1934), but his description did not fulfill the nomenclatorial rules (ICZN Code, 1999), since no type species was assigned and no diagnostic features were given (Stenzel, 1971, p. 1215). Cox in Cox and others (1969, p. 306) designated the type species and provided its diagnosis.

  • Stratigraphic range.—Middle Triassic (upper Ladinian)—Upper Triassic (Carnian). Bittner (1895) described the type species from the Saint Cassian Formation, regarded as Carnian in age (Fürsich & Wendt, 1977). Cox and others (1969) assigned a Ladinian age, probably on the basis of Venzo's paper (1934; see above).

  • Paleogeographic distribution.—western Tethys (Fig. 13).

  • Tethys domain: Middle Triassic: late Ladinian of Italy (Cox & others, 1969); Late Triassic: Carnian of Italy (Bittner, 1895).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Its external morphology and the presence of byssal notch indicate a probable byssate mode of life. Possibly, like other members of the family, it spent the early stages of development fixed by the byssus, but adults could have lived partially buried in the sediment. There is no information about the type of sediment in which it was found.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206). There is no information about Stefaninia shell mineralogy or microstructure. We use data provided for the family Pteriidae. Outer shell layer: calcite (simple prismatic). Middle and inner shell layer: aragonite (nacreous).

  • Figure 13.

    Paleogeographical distribution of Pteriidae (Pteria, Arcavicula, Rhaetavicula, Stefaninia). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f13_01.jpg

    Family BAKEVELLIIDAE King, 1850
    Genus BAKEVELLIA King, 1848, p. 10

  • Neave (1939, p. 385) lists “Miller, 1877, p. 185, pro Bakewellia King, 1848” as author of the genus. Nevertheless, Miller (1877, p. 185) did not indicate he was proposing either an emendation or a replacement name, and already in 1850 King (p. 166–171, 255) spelled it consistently as Bakevellia, although he stated (p. 166, footnote) that the name was dedicated to Mr. Bakewell.

  • Type species.—Avicula antiqua Münster in Goldfuss, 1835 in 1833–1841, p. 126, non Defrance, 1816.

  • Remarks.—Several subgenera were proposed within Bakevellia (see Damborenea, 1987b, p. 125–126), but Muster (1995) regarded almost all to be synonyms, considering only two of them to be valid, as also did Cox and others (1969): B. (Bakevellia) King, 1848, and B. (Bakevelloides) Tokuyama, 1959a. The subgenera described for our study interval were Neobakevellia Nakazawa, 1959, Integribakevellia Farsan, 1972, Costibakevellia Farsan, 1972, and Spia Skwarko, 1981 (see list of synonyms for both subgenera in Muster, 1995, p. 29, 42).

  • Stratigraphic range.—upper Permian—Upper Cretaceous. Cox and others (1969) assigned it a Permian—Upper Cretaceous range. Muster (1995) maintained this range, noting that the first record of the genus is dated as upper Permian. Sepkoski (2002) considered the oldest record to be Carboniferous, but we will not take this into account, since it is based on a personal communication by Yancey to Sepkoski (indicated in Sepkoski, 2002), which has not been published.

  • Paleogeographic distribution.—Cosmopolitan.

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. The mode of life of bakevelliids is difficult to identify as that they do not have living representatives to compare with, and the study of the morphology alone does not always provide good results, because morphology traits are sometimes contradictory. It is also helpful to interpret the paleoecology of the environments in which the specimens are found. Most species assigned to Bakevellia are almost equivalve, they have a shallow byssal sinus and an anterior lobe, features that indicate an endobyssate way of life, living with the sagittal plane almost vertical (S. M. Stanley, 1972). This interpretation was proposed by Damborenea (1987b) for Bakevellia (Neobakevellia?) pintadae Damborenea, 1987b, and by Aberhan and Muster (1997) for Bakevellia (Bakevellia) waltoni (Lycett, 1863). However, Seilacher (1984) interpreted Bakevellia subcostata (Goldfuss, 1835 in 1833–1841) as reclined and partially buried in the sediment, resting on its left valve, with the commissure plane being almost horizontal.

  • Mineralogy.—Bimineralic (Márquez-Aliaga & Martínez, 1990a; Carter, 1990b). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus GERVILLELLA Waagen, 1907, p. 98

  • Type species.—Perna aviculoides J. Sowerby, 1814, p. 147.

  • Remarks.—Fürsich and Werner (1988, p. 112) argued that there are no substantial differences between Gervillia Defrance, 1820, and Gervillella to consider them as independent taxa, and they included Gervillella as a subgenus of Gervillia. We follow Freneix (1965) and Muster (1995) in treating them as separated genera.

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Upper Cretaceous (?) (Aberhan, 1998a; Muster, 1995). Several authors extended the range back to the Triassic (e.g., Gillet, 1924; Hayami, 1957a; Freneix 1965; Cox & others, 1969; Geyer, 1973; Lazo, 2003), but none of them justified this statement, and they did not figure any Triassic specimens. All except Geyer (1973) simply listed the stratigraphic range of several genera. Geyer mentioned the presence of Gervillella sp. from the Norian Payandé Formation in Colombia, but he did not figure it. It is possible that some Triassic species assigned to Gervillia should be referred to Gervillella instead, but there is no published reference of their presence in this period. The oldest confirmed record dates from the Hettangian (Aberhan, 1998a), and the youngest from the Upper Cretaceous (Muster, 1995). Sepkoski (2002) assigned the last appearance to the Maastrichtian, but it was not possible to see the original data source. Muster (1995) did not specify the stage, and there is no further information about this topic. However, it is not uncommon to find the genus mentioned from the Lower Cretaceous (Lazo, 2003, 2007a).

  • Paleogeographic distribution.—western Tethys, Austral, and Circumpacific (Fig. 14). The genus had a particularly wide distribution mainly during the Middle and Late Jurassic (Vörös, 1971; Fürsich & Werner, 1988; Liu, 1995; Muster, 1995; Sha & Grant-Mackie, 1996; Delvene, 2003; Sha, Johnson, & Fürsich, 2004).

  • Tethys domain: Early Jurassic: Hettangian—Sinemurian of England and Morocco (Liu, 1995).

  • Austral domain: Early Jurassic: Hettangian—Sinemurian of Southern Andes (Damborenea, 1996a; Damborenea & Lanes, 2007).

  • Circumpacific domain: Early Jurassic: Hettangian—Sinemurian of Canada (Aberhan & Muster, 1997; Aberhan, 1998a); Sinemurian of Chile (Aberhan, 1994a).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Like most bakevelliids, Gervillella presents features that indicate a semi-infaunal endobyssate mode of life (S. M. Stanley, 1972; Aberhan & Muster, 1997) or so-called mud-sticker (Seilacher, 1984). All species assigned to this genus are almost equivalve, they possess an anterior auricle, and their external morphology is elongate spear-shaped. Thanks to its elongated shape, Gervillella could probably bury deeper than other bakevelliids (S. M. Stanley, 1972; Aberhan & Muster, 1997), similar to members of the family Pinnidae (S. M. Stanley, 1972). Although neither Damborenea (1987b) nor Aberhan and Muster (1997) found evidence in their specimens of a byssal notch, according to Cox (1940), one of the characters that defines the genus is that the anterior auricle extends anteroventrally and is limited in the left valve by a deep groove, which indicates the position of the byssus.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 207; Carter, 1990b, p. 336). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus GERVILLIA Defrance, 1820, p. 502

  • Type species.—Gervillia solenoidea Defrance, 1824a, p. 316.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Cretaceous (Maastrichtian) (Lerman, 1960; Abdel-Gawad, 1986). Both Cox and others (1969) and Muster (1995) indicated its range as beginning at the Upper Triassic, but there are Middle Triassic records of Gervillia, referred to the species G. joleaudi (Schmidt, 1935) from the Anisian of Israel (Lerman, 1960) and Ladinian of Spain (Márquez-Aliaga, 1985). These were not included in Musters monograph (1995), but Waller and Stanley (2005) indicated that the generic assignation of this species requires revision. However, these authors based their opinion, exposed in the discussion of their new subgenus Gervillaria (Baryvellia), in data from Schmidt (1935), who compared G. joleaudi with Gervillia alberti Credner, 1851. According to Márquez-Aliaga (1985), this last species is a true Bakevellia; therefore, Gervillia joleaudi should be considered as a representative of Gervillia from the Sephardic province of the Tethys domain. With regard to the uppermost stratigraphic occurrence, all agreed that the genus disappeared in the Upper Cretaceous. Within our study interval, we will only consider the subgenus Cultriopsis Cossmann, 1904. Boyd and Newell (1979) doubtfully assigned some of their specimens from the Permian of Tunisia to this subgenus.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 14). Although Escobar (1980) reported Gervillia from Hettangian—Sinemurian beds of Chile, only one of the specimens could be attributed with doubt to this genus (Damborenea, 1987b), so it will not be taken into account in the Austral domain in this temporal range. If the genus is present in this domain, it has occurred since the Pliensbachian.

  • Tethys domain; Middle Triassic; Anisian of Israel (Lerman, 1960); Ladinian of Spain (Márquez-Aliaga, 1983, 1985; Márquez-Aliaga, Hirsch, & López-Garrido, 1986; Márquez-Aliaga & Martínez, 1990a, 1996; Budurov & others, 1991; Márquez-Aliaga & Montoya, 1991; Martinez & Márquez-Aliaga, 1994; Niemeyer, 2002; Márquez-Aliaga & Ros, 2003); Late Triassic; China (Muster, 1995); Carnian of Italy (Fürsich & Wendt, 1977; Muster, 1995), Spain (Martín-Algarra & others, 1993), Slovenia (Jurkovsek, 1978), China (Wen & others, 1976); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Austria (Tanner, Lucas, & Chapman, 2004); Early Jurassic; early Hettangian of Tibet (China) (J. Yin & McRoberts, 2006); Hettangian—Sinemurian of Vietnam (Sato & Westermann, 1991).

  • Circumpacific domain; Late Triassic; Japan (Muster, 1995); Carnian of Japan (Tamura & others, 1978); Norian of Oregon (Newton, 1986; Newton & others, 1987); Early Jurassic; Hettangian of Japan (Hayami, 1957a, 1964, 1975; Muster, 1995).

  • Paleoautoecology.—B-Ps, Se-E, S, Endo-Epi, Sed; By. Some species of Gervillia are morphologically similar to species of Gervillella and Gervillancea (see discussion on their mode of life, p. 40, 44). These two genera are interpreted as having a semi-infaunal endobyssate mode of life (Waller & Stanley, 2005). Formerly, Muster (1995) regarded this mode of life to be unlikely for Gervillia, since it had a very short ligament area that would not be enough to maintain the shell stability. Seilacher (1984) suggested a pseudoplanktonic mode of life for some species of Gervillia, as epibyssate on ammonoids. He called these forms pendent forms. However, other species of Gervillia were interpreted as semi-infaunal endobyssate or mud-stickers (Seilacher, Matyja, & Wierzbowski, 1985). These interpretations are based on the external shell morphology and on the ecological analysis of the depositional environment in which the specimens were found (see Seilacher, 1984; Seilacher, Matyja, & Wierzbowski, 1985). In the Muschelkalk of the Iberian Range (Spain), specimens recorded in marls are common, and they are usually found in semi-infaunal life position. Newton (in Newton & others, 1987) and Damborenea (1987b) interpreted their specimens as epibyssate, but they noted that the shells also had features indicative of a semi-infaunal habit. These are usually found associated with corals.

  • Mineralogy.—Bimineralic (De Renzi & Márquez-Aliaga, 1980; Carter, 1990a; Márquez-Aliaga & Martínez, 1990a; Martínez & Márquez-Aliaga, 1994). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers; aragonite (nacreous).

  • Genus HOERNESIA Laube, 1866, p. 52

  • Type species.—Mytulites sodalis Schlotheim, 1823 in 1822–1823, p. 112.

  • Stratigraphic range.—Lower Triassic (Olenekian)—Upper Triassic (Rhaetian) (Hallam, 1981; Dagys & Kurushin, 1985). Cox and others (1969) indicated a Triassic—Middle Jurassic range, although some authors believed Hoernesia disappeared in the Rhaetian (Hallam, 1981, 1990; Hallam & others, 2000). However, Muster (1995, p. 89) extended its range to the Middle Jurassic, because she included Gervillia radians Morris & Lycett, 1853 in 1851—1885, in the synonymy list of Hoernesia sodalis (Schlotheim, 1823 in 1822–1823); besides, she did not consider Hoernesia to be present in the Early Triassic. The first record of Hoernesia dates from the Early Triassic (Dagys & Kurushin, 1985; Posenato, 2008a).

  • Paleogeographic distribution.—Tethys and Boreal (Fig. 14).

  • Tethys domain; Early Triassic: Italy (Neri & Posenato, 1985), Yunnan (China) (Guo, 1985); Middle Triassic; Bulgaria (Stefanov, 1942; Encheva, 1969), Spain (Via, Villalta, & Esteban, 1977; Márquez-Aliaga, 1983, 1985; Márquez-Aliaga & Martínez, 1996; Márquez-Aliaga & others, 2001, 2002, 2004; Márquez-Aliaga & Ros, 2002), Italy (Posenato, 2002; Posenato & others, 2002), Germany (Fuchs & Mader, 1980; Hagdorn, 1982; Hagdorn & Simon, 1983, 1991), Poland (Senkowiczowa, 1985; Kaim, 1997), Hungary (Szente, 1997); Anisian of China (Sha, Chen, & Qi, 1990); Anisian—Ladinian of northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of the Alps (Austria and Italy) (Arthaber, 1908), Germany (Ürlichs, 1978); Late Triassic; China (Cowper-Reed, 1927), Malaysia (Tamura & others, 1975); Carnian of Italy (Laube, 1865), Slovenia (Jurkovsek, 1978); Norian of China (Lu, 1981); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Burma (Healey, 1908), Iran (Repin, 2001), Tibet (J. Yin & Enay, 2000).

  • Boreal domain: Early Triassic: Olenekian of northern Siberia (Dagys & Kurushin, 1985).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Hoernesia is, characterized by a strongly inequivalve shell and twisted valves, and thus it was interpreted as a so-called twisted recliner by Seilacher (1984). It also has an umbonal shell thickening, so its life position consisted of this area being introduced into the sediment, with the posterior part of the valves sticking out (Savazzi, 1984; Seilacher, 1990; Muster, 1995). The inferred life position is similar to that of Gervillaria alaeformis (J. Sowerby, 1819) (see discussion about the mode of life of this species, below). Seilacher (1990) suggested chemosymbiosis as a functional explanation for this curious life position.

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 337). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus LANGSONELLA Patte, 1926, p. 139

  • Type species.—Gervilleia (Cultriopsis) elongata Mansuy, 1919, p. 7.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Diener, 1923; Komatsu, Huyen, & Huu, 2010). Cox and others (1969) referred this genus to the Triassic without further explanation and indicated it is monospecific. According to Diener (1923), the type species was described by Mansuy from the Carnian of Tonkin, which today covers most of Vietnamese northern regions. Later, Vu Khuc and Huyen (1998) mentioned L. elongata (Mansuy, 1919) as being typical from Ladinian beds in the same area, and, recently, Komatsu, Huyen, and Huu (2010) reported it from the Anisian and Ladinian of northern Vietnam.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 14).

  • Tethys domain: Middle Triassic: Anisian—Ladinian of northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of Tonkin (north of Vietnam) (Vu Khuc & Huyen, 1998); Late Triassic: Carnian of Tonkin (Vietnam) (Diener, 1923).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. We did not find any figures of the genus; therefore, it is difficult for us to refer it to a particular mode of life, but according to its description in Cox and others (1969), we consider it to be similar to Hoernesia.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206—207). There are no data on Langsonella shell structure. We used data provided for the family Bakevelliidae. Outer shell layer: calcite (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Genus CUNEIGERVILLIA Cox, 1954, p. 48

  • Type species.—Gervillia hagenowii Dunker, 1846, p. 37.

  • Remarks.—Cox (1954) described Cuneigervillia and included Edentula Waagen, 1907, p. 96 (non Nitzch, 1820, p. 189) as its synonym. Later, in Cox and others (1969), he regarded Edentula [= Waagenorperna Tokuyama, 1959a, p. 151] as a separate genus and included it into the Isognomonidae. In turn, Tokuyama (1959a) proposed the name Waagenoperna to replace Edentula Waagen, 1907. He pointed to significant differences between the Cuneigervillia type species designated by Cox (1954) (Gervillia hagenowii Dunker, 1846) and some species attributed to Edentula (E. lateplanata Waagen, 1907, and E. triangularis Kobayashi & Ichikawa, 1952). He designated Edentula lateplanata as the type species of Waagenoperna, maintaining the two genera as distinct taxa, relating G. hagenowii to the Bakevelliidae and E. lateplanata and E. triangularis to the Isognomonidae. Muster (1995) decided to include Cuneigervillia with the Isognomonidae, believing that although Cuneigervillia externally seems to be a bakevelliid, it possesses certain characteristics that are typical of the Isognomonidae, such as terminal or sub terminal beaks and a toothless adult hinge. It is difficult to decide because both families share many characteristics, but the lack of teeth in the adult stage is not a critical feature because it also occurs in certain bakevelliids; for example, in some species of Bakevellia (Bakevellia) the dentition is obsolete in adults (Cox & others, 1969, p. 306). The Treatise diagnosis states “hinge teeth present at least in lower growth stages ….” Regarding the beaks, they can either be subterminal (e.g., Aguilerella) or terminal (e.g., Gervillia). Furthermore, Cuneigervillia presents the typical teeth of Bakevellia in juvenile stages. Therefore, according to Cox and others (1969), we include Cuneigervillia in the Bakevelliidae.

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Lower Cretaceous (?) (Cox & others, 1969). Cox and others (1969) assigned it a lower Liassic to Lower Cretaceous range, since Tokuyama (1959a) referred several Carnian species to Waagenoperna that were initially assigned by Cox (1954) to Cuneigervillia.

  • Paleogeographic distribution.—western Tethys (Fig. 14).

  • Tethys domain: Early Jurassic: Europe and northern Africa (Cox & others, 1969); Hettangian of France (Freneix & Cubaynes, 1984), south of England (Warrington & Ivimey-Cook, 1990), Spain (Gómez, Goy, & Márquez-Aliaga, 2005; Márquez-Aliaga, Damborenea, & Goy, 2008a, 2008b; Márquez-Aliaga & others, 2010); Hettangian—Pliensbachian of northwestern Europe (Hallam, 1987); Sinemurian of Portugal (Liu, 1995).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Cuneigervillia was interpreted as a semi-infaunal endobyssate bivalve (S. M. Stanley, 1972), as were most members of Bakevelliidae.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206–207). There are no data on Cuneigervillia mineralogy and shell microstructure. Data provided for the family Bakevelliidae are used here. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus GERVILLARIA Cox, 1954, p. 49

  • Type species.—Modiola? alaeformis J. Sowerby, 1819, p. 93.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Cretaceous (Turonian) (Komatsu, Chen, & others, 2004; Muster, 1995). Cox and others (1969) assigned this genus a Jurassic–Cretaceous range in Europe, but, since then, new records have extended its stratigraphic range. The oldest record is Anisian (Komatsu, Chen, & others, 2004) and the youngest is Turonian (Muster, 1995).

  • Paleogeographic distribution.—Tethys, Austral, and Circumpacific (Fig. 14).

  • Tethys domain: Middle Triassic: Muschelkalk of Germany (Muster, 1995); Anisian of Qingyan (southern China) (Komatsu, Chen, & others, 2004); Late Triassic: southwestern China (Komatsu, Chen, & others, 2004); Rhaetian of Lombardy (Italy) (Muster, 1995), Italian Alps and Vietnam (Hautmann, 2001b), western Carpathians (Slovakia) (Tomašových, 2004), Tibet (China) (J. Yin & Grant-Mackie, 2005); Norian—Rhaetian of Iran (Hautmann, 2001b).

  • Austral domain: Early Jurassic: Sinemurian of the Andean Basin (Aberhan & Fürsich, 1997); Hettangian—Sinemurian of the Andean Basin (Damborenea & Manceñido, 2005b).

  • Circumpacific domain: Middle Triassic: Ladinian of western Nevada (Waller & Stanley, 2005); Late Triassic: Norian of southeastern Sonora (Mexico) (McRoberts, 1997a); Early Jurassic: Sinemurian of ?western Canada (Aberhan, 1998a), Chile (Aberhan, 1994a).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Some species, such as Gervillaria alaeformis (J. Sowerby, 1819) (Muster, 1995, fig. 37) and Gervillaria pallas (A. F. Leanza, 1942) (Damborenea, 1987b, fig. 7; Muster, 1995, fig. 43), have a strongly inequivalve and inequilateral shell, with the left valve being more convex than the right, twisted valves, and an elongated posterior auricle. These species were interpreted as having a semi-infaunal endobyssate mode of life, probably supplemented by byssal attachment (Damborenea, 1987b; Aberhan & Muster, 1997). Seilacher (1984, fig. 7) proposed an analogous interpretation for a similar species, Hoernesia tortuosa, including it as a twisted recliner. This category was also used by Aberhan and Muster (1997) for their specimens of G. pallas. Gervillaria (Baryvellia) ponderosa Waller in Waller & Stanley, 2005, was also considered semi-infaunal endobyssate, but this species had a peculiar external morphology, which probably means that its life position was also special (Waller & Stanley, 2005) (see discussion on Gervillancea mode of life, below). However, due to the mytiliform appearance of some species referred to Gervillaria, these were interpreted as epibyssate (S. M. Stanley, 1972). Gervillaria ashcrofiensis (Crickmay, 1930a) (see Muster, 1995, fig. 39) was also thought to be epibyssate, according to its nearly equivalve shell, umbonal thickening, and flat anteroventral area, among other characteristics (see Aberhan & Muster, 1997).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206–207). There are no data on Gervillaria mineralogy or shell microstructure. Data provided for family Bakevelliidae are used here. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Figure 14.

    Paleogeographleal distribution of Bakevelliidae (Gervillella, Gervillia, Hoernesia, Langsonella, Cuneigervillia, Gervillaria, Gervillancea, Songdaella, Aguilerella, Towapteria, Virgellia, Gervilleiopernd). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f14_01.jpg

    Genus GERVILLANCEA Skwarko, 1967, p. 54

  • Type species.—Gervillancea coxiella Skwarko, 1967, p. 54.

  • Stratigraphic range.—Upper Triassic (Carnian—Norian) (Skwarko, 1967). Gervillancea is a monospecific genus only known from Upper Triassic of New Guinea (Skwarko, 1967; Muster, 1995; Waller & Stanley, 2005). Although it was described before the publication of the Treatise (Cox & others, 1969), it was included neither there nor in Sepkoski (2002).

  • Paleogeographic distribution.—Southern Tethys (Fig. 14). Gervillancea was endemic in the Australian province (according to Damborenea, 2002b) of the Tethys domain. It was only reported from Papua New Guinea (Skwarko, 1967).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. One of the most striking features of this genus is its extremely long anterior auricle, which distinguishes it from almost all other genera of Bakevelliidae. According to Waller and Stanley (2005), there are two species, Gervillaria (Baryvellia) ponderosa Waller in Waller & Stanley, 2005, and Gervillia joleaudi (Schmidt, 1935), that also have this feature. These two species, together with Gervillancea coxiella, may be a good example of evolutionary convergence, but, in fact, Gervillia joleaudi lacks an anterior auricle. The external shape of Gervillancea is very asymmetric and inequivalve. None of the specimens figured by Skwarko (1967) bears a byssal notch, but if the species was byssate, like other bakevelliids, the byssus probably emerged from the shell under the anterior auricle. Taking into account that it probably lived anchored to the substrate with the anterior auricle, a strong byssus was not necessarily needed to maintain stability inside the substrate. Pedal and byssal muscle scars indicate that these muscles were strong and able to aid the shell to penetrate up to a third of its dorsal line into the sediment, since the convexity of the shell increases at this point and thus limits the burial depth (see Waller & Stanley, 2005, p. 27—29). The bivalve most probably introduced itself into the sediment during the juvenile stages, since the anterior auricle is comparatively thin and thus inadequate to penetrate the sediment in the adult stage.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206—207). No data are available about the shell of Gervillancea, but it was probably bimineralic, as in other Bakevillidae (J. D. Taylor, Kennedy, & Hall, 1969). Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus SONGDAELLA Vu Khuc, 1977b, p. 50 [180]

  • Type species.—Songdaella graciosa Vu Khuc, 1977b, p. 51 [182].

  • Remarks.—Vu Khuc (1977b) assigned Songdaella to the Bakevelliidae, but he indicated that the genus had intermediate characters between this family and the Isognomonidae. Muster (1995) did not include it in her monograph about the family Bakevelliidae and did not comment about its systematic position. In the absence of more information, we include Songdaella in Bakevelliidae.

  • Stratigraphic range.—Upper Triassic (Norian) (Vu Khuc, 1977b). Songdaella was only recorded from Norian beds (Vu Khuc, 1977b; J. Chen, 1982a; Vu Khuc & Huyen, 1998).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 14). Songdaella was endemic to southern East Asia (Vu Khuc & Huyen, 1998).

  • Tethys domain; Norian of northern Vietnam (Vu Khuc, 1977b) and southern China (J. Chen, 1982a).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Songdaella is characterized by a mytiliform shell, and some of the specimens figured by Vu Khuc (1977b) are similar to Mytilus. The author related his new genus to Aguilerella according to its external morphology, which was interpreted as epibyssate by S. M. Stanley (1972), due to its external similarity with Mytilus and Myalina.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206—207). There are no data about the shell of Songdaella. We use the data predominant in the family Bakevelliidae. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus AGUILERELLA Chavan, 1951, p. 211

  • Type species.—Perna kobyi de Loriol, 1901, p. 99.

  • Stratigraphic range.—Upper Triassic (Rhaetian)—Lower Cretaceous (Hauterivian) (J. Yin & McRoberts, 2006; Kozai, Ishida, & Kondo, 2006).

  • Many authors restricted it to a Lower Jurassic—Upper Jurassic range (Cox & others, 1969; Muster, 1995; Sepkoski, 2002). This range was extended due to new records from the Rhaetian of Tibet (J. Yin & McRoberts, 2006) and from the Hauterivian (Kozai, Ishida, & Kondo, 2006).

  • Paleogeographic distribution.—Eastern Tethys and Circumpacific (Fig. 14). Although during the study interval it was only reported from eastern Tethys and Austral domains, from Toarcian times it extended also to western Tethys and Boreal regions (see Fürsich, 1982; Liu, 1995; Muster, 1995; J. Yin & Grant-Mackie, 2005; Zakharov & others, 2006).

  • Tethys domain; Late Triassic; Rhaetian of Tibet (China) (J. Yin, H. Yao, & Sha, 2004; J. Yin & McRoberts, 2006); Early Jurassic; Hettangian of China (J. Chen & Liu, 1981; J. Yin & McRoberts, 2006).

  • Circumpacific domain: Early Jurassic: Sinemurian of Chile (Aberhan, 1994a; Aberhan & Fürsich, 1997), Canada (Poulton, 1991); Hettangian—Sinemurian of South America (Damborenea, 1996a).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Due to its mytiliform aspect, it was thought to be epibyssate (S. M. Stanley, 1972). Aguilerella is one of the few bakevelliids, together with Songdaella, that are interpreted to be epibyssate due to their triangular form, without anterior lobe and with terminal beaks (Damborenea, 1987b). In some species, a gregarious behavior was observed (Fürsich, 1982; Damborenea, 1987b).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206—207). There are no specific data about the shell of Aguilerella. Data provided for the family Bakevelliidae. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus TOWAPTERIA Nakazawa & Newell, 1968, p. 59

  • Type species.—Towapteria nipponica Nakazawa & Newell, 1968, p. 59.

  • Stratigraphic range.—lower Permian (Sakmarian)—Lower Triassic (Induan) (Hayami & Kase, 1977; S. Yang, Wang, & Hao, 1986). Nakazawa and Newell (1968) proposed the genus Towapteria with material from the middle Permian of Japan. Cox and others (1969) did not take it into account in the Treatise, probably due to the proximity of publication. Hayami and Kase (1977) assigned it a Sakmarian—upper Permian range with some doubts. Towapteria was later reported from the Tethyan Early Triassic (see paleogeographic distribution below). Nevertheless, Muster (1995) assigned it an upper Permian, ?Upper Triassic, Middle Jurassic discontinuous range, due to the inclusion of some species previously assigned to Gervillia and Costigervillia (see synonymy list in Muster, 1995, p. 92). She did not see the material personally and the addition of most these species to the synonymy list was done doubtfully due to the lack of internal reliable characters for classification. Furthermore, Muster (1995) did not take into account some Tethyan, Early Triassic species, such as T. scythica (Wirth), among others.

  • Paleogeographic distribution.—Tethys and ?Circumpacific (Fig. 14).

  • Tethys domain: late Permian: Changhsingian of Italy (Farabegoli, Perri, & Posenato, 2007); Early Triassic: Induan of Italy (Broglio-Loriga, Neri, & Posenato, 1980, 1986; Broglio-Loriga, Masetti, & Neri, 1982; Neri, Pasini, & Posenato, 1986; Broglio-Loriga & others, 1988, 1990; Posenato, 1988, 2008a), China (S. Yang, Wang, & Hao, 1986; L. Li, 1995; Tong & Yin, 2002; Waller & Stanley, 2005; Komatsu, Huyen, & Chen, 2007).

  • Circumpacific domain: late Permian: ?Japan (Nakazawa & Newell, 1968; Hayami & Kase, 1977).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. It is hard to assign a specific life habit to Towapteria, because there are some features indicative of an epibyssate and others of an endobyssate mode of life. Due to its external similarity to Costigervillia Cox & Arkell, 1948 in 1848—1850 (a genus not included here because it first appeared in the Middle Jurassic), we can assume that Towapteria was endobyssate, but its smooth and lob ate anterior auricle and radially ribbed shell indicate otherwise. We suggest it was byssate and probably lived with the anterior part introduced in the sediment. The ribs probably helped to stabilize the shell, as was postulated for Costigervilla by Seilacher (1984).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206–207). No data are available about the shell of Towapteria. Data provided for family Bakevelliidae. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus VIRGELLIA Freneix, 1965, p. 61

  • Type species.—Virgellia coxi Freneix, 1965, p. 64.

  • Remarks.—Fürsich & Werner (1988) considered Virgellia as subgenus of Gervillia Defrance, 1820, since, in their opinion, it had intermediate features between Gervillia and Gervillella (which they also regarded as subgenus of Gervillia). Following Freneix (1965) and Muster (1995), we regard Virgellia as a separate genus. Freneix (1965) proposed Virgellia and originally included in it three species: V. coxi Freneix, 1965, V. fittoni (Sharpe, 1850), and V. sobralensis (Sharpe, 1850). Later, Muster (1995) added V. simbaiana (Skwarko, 1967) to V. coxi and V. sobralensis (see synonym list in Muster, 1995, p. 94–95).

  • Stratigraphic range.—Upper Triassic (Carnian)—Upper Jurassic (Kimmeridgian) (Muster, 1995). Cox and others (1969) and Sepkoski (2002) did not take Virgellia into account. The type species was originally described from Callovian sediments, and the original range assigned to the genus was Bajocian to Kimmeridgian (Freneix, 1965). Later, its range was extended by the inclusion of V. simbaiana by Muster (1995). The oldest record of Virgellia is from Carnian beds (Skwarko, 1967, 1981) and the youngest from Kimmeridgian beds (Freneix, 1965). It has not been recorded from the Lower Jurassic.

  • Paleogeographic distribution.—Southern Tethys (Fig. 14). Although during the interval of time under consideration it was only known from southern Tethys, during the Middle and Late Jurassic it was reported also from Tunisia (Freneix, 1965; Holzapel, 1998) and Portugal (Fürsich & Werner, 1988).

  • Tethys domain: Late Triassic: Carnian—Norian of Papua New Guinea (Skwarko, 1967, 1981; Muster, 1995).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Virgellia was externally similar to Gervillella and probably had the same mode of life, though slightly less buried into the substrate, as it lacked the Gervillella spear shape but had a more developed anterior lobe (Muster, 1995).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 206—207). No data about Virgellia shell mineralogy or microstructure are available. Data provided for the family Bakevelliidae. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus GERVILLEIOPERNA Krumbeck, 1923b, p. 76

  • Type species.—Gervilleioperna timoriensis Krumbeck, 1923b, p. 76.

  • Remarks.—Although Cox and others (1969) and other authors included Gervilleioperna in the Isognomonidae, we assign it to the Bakevelliidae following Damborenea (1987b), noting that it had a pteriform shell and a strong radial carina.

  • Stratigraphic range.—Lower Jurassic (Sinemurian)—Middle Jurassic (Aalenian) (Aberhan, 1994a; Aberhan & Hillebrandt, 1996). The oldest record of Gervilleioperna is from Sinemurian beds (Aberhan, 1994a). During the Toarcian, its distribution became restricted to the Circumpacific domain (in Chile) (Aberhan & Hillebrandt, 1996).

  • Paleogeographic distribution.—Circumpacific (Fig. 14). Although Gervilleioperna was present beginning in Sinemurian times, it reached a diversity peak in the Pliensbachian and became extinct during the Aalenian. It is especially abundant in the Tethys domain during the Pliensbachian (Accorsi-Benini & Broglio-Loriga, 1975; Buser & Debeljak, 1994; Liu, 1995; Aberhan & Fiirsich, 1997; Fraser & Bottjer, 2001a, 2001b; Fraser, Bottjer, & Fischer, 2004), while during the Sinemurian, it was only found in the Circumpacific domain. It was also reported from the northern part of the Austral domain during the Pliensbachian (Damborenea, 1987b). Gervilleioperna was not recorded in high paleolatitudes, and it was therefore restricted to warm waters (Damborenea, 1996a). It had a pan-Tethyan distribution, ranging from the Pacific coast (South America) through southern Europe and northern Africa to the eastern Tethys (Timor).

  • Circumpacific domain; Early Jurassic; Sinemurian of Chile (Aberhan, 1994a; Aberhan & Muster, 1997).

  • Paleoautoecology.—B, Se, S, Endo, R, Sed; By. Along with Lithiotis, Lithioperna, Cochlearites, and Mytiloperna, Gervilleioperna was a reef builder, especially during Pliensbachian times, replacing the coral reefs of the Late Triassic (Fraser, Bottjer, & Fischer, 2004). Gervilleioperna was interpreted as being reclined, lying on its left valve (Seilacher, 1984; Damborenea 1987b; Fraser, Bottjer, & Fischer, 2004). Buser and Debeljak (1994) interpreted it as epifaunal epibyssate similarly to Recent Isognomon species, but we believe the semi-infaunal endobyssate option is more reasonable, because its left valve is much heavier than the right and it would have easily sunk into the soft sediment (Damborenea, 1987b). Seilacher (1984) interpreted it as a cup-shaped recliner in soft sediments, similar to Gryphaea. Fraser, Bottjer, and Fischer (2004, fig. 10A) agreed, but they classified it as epifaunal. Aberhan and Hillebrandt (1996) suggested that Gervilleioperna (Gervilleiognoma) aurita Aberhan & Hillebrandt was semiinfaunal endobyssate, lying on the umbonal region and the anterior part of its left valve, and with its commissural plane oblique to the substrate surface. Since a byssal notch is observed (Cox & others, 1969, p. 325), it most likely was endobyssate.

  • Mineralogy.—Aragonitic (Accorsi-Benini & Broglio-Loriga, 1975; Carter, 1990a; Carter, Barrera, & Tevesz, 1998). Accorsi-Benini and Broglio-Loriga (1975) studied the shell of their specimens of Gervilleioperna, but they did not check the mineralogical composition (aragonite or calcite) of the shell layers. Carter (1990a) noted that further analysis is needed to determine whether the outer layer contains prismatic calcite. Outer shell layer: aragonite-calcite (?). Inner shell layer: aragonite (?).

  • Family CASSIANELLIDAE Ichikawa, 1958
    Genus CASSIANELLA Beyrich, 1862, p. 9

  • Type species.—Avicula gryphaeata Münster in Goldfuss, 1835 in 1833–1841, p. 127.

  • Stratigraphic range.—?Permian, Middle Triassic (Anisian)—Upper Triassic (Rhaetian). Cox and others (1969) assigned Cassianella a Triassic and probably Permian range. Ciriacks (1963) and Waterhouse (1987) mentioned Cassianella from the lower and middle Permian (up to Guadalupian), but specimens in both papers were referred to the genus by external morphology only, and in neither reference were internal characters described. Although Ciriacks (1963, p. 31) mentioned Cassianella from the Lower Triassic, we did not find any information about this, and he did not figure any specimens. Cassianella was common from the Anisian to Rhaetian (see paleogeographic distribution).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 15).

  • Tethys domain: Middle Triassic: Anisian of southern China (Komatsu, Chen, & others, 2004); Anisian—Ladinian of Bulgaria (Stefanov, 1942), Italy (Posenato, 2008a); Ladinian of Spain (Márquez-Aliaga, 1983, 1985; Márquez-Aliaga, García-Forner, & Plasencia, 2002), Slovakia (Kochanová, Mello, & Siblík, 1975), Israel (Lerman, 1960), Italy (Rossi Ronchetti, 1959); Late Triassic: Sumatra (Krumbeck, 1914), Alps (Austria) (Tomašových, 2006a, 2006b), China (Cowper-Reed, 1927; J. Chen, 1982a; Gou, 1993); Carnian of the Italian Alps (Bittner, 1895; Leonardi, 1943; Fürsich & Wendt, 1977), Carpathians (Bittner, 1901a), Turkey (Bittner, 1891), Spain (Márquez-Aliaga & Martínez, 1996), Israel (Lerman, 1960); Norian of western Caucasus (Ruban, 2006a), China (Wen & others, 1976; J. Chen & Yang, 1983), Singapore (Kobayashi & Tamura, 1968a; Norian—Rhaetian of Iran (Hautmann, 2001b); late Rhaetian ofTibet (J. Yin & McRoberts, 2006), Pamira (Polubotko, Payevskaya, & Repin, 2001), Alps (Italy) (Desio, 1929; McRoberts, Newton, & Allasinaz, 1995), India (Healey, 1908).

  • Circumpacific domain: Late Triassic: Peru (Körner, 1937), Japan (Kobayashi & Ichikawa, 1949a; Tamura, 1990); Norian of Oregon (United States) (Newton, 1986, 1989; Newton & others, 1987), southwestern Alaska (McRoberts & Blodgett, 2000), Canada (Tozer, 1962, 1970); Rhaetian of Nevada (United States) (Silberling, 1961; Laws, 1982); Norian—Rhaetian of Chile (Chong & Hillebrandt, 1985).

  • Austral domain: Late Triassic: Carnian of New Zealand (Trechmann, 1918; Marwick, 1953); Norian—Rhaetian of Argentina (Riccardi & others, 1997, 2004; Damborenea & Manceñido, 2012).

  • Boreal domain: Late Triassic: northern Siberia (Kurushin, 1990; Polubotko & Repin, 1990); Carnian of Primorie (Kiparisova, 1972); Norian—Rhaetian of northeastern Russia (Kiparisova, Bychkov, & Polubotko, 1966).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Cassianellids are generally interpreted as being reclining bivalves, lying on their left valve on the sediment (Fürsich & Wendt, 1977; Laws, 1982; Newton in Newton & others, 1987; Hautmann, 2001b). Some species, such as C. lingulata Gabb, 1870, and C. angusta Bittner, 1891, were thought by Laws (1982) and Newton (in Newton & others, 1987), respectively, to be byssate, although there is no byssal notch.

  • Mineralogy.—Aragonitic (Carter, 1990b, p. 338–339; Carter, Barrera, & Tevesz, 1998). Carter, Barrera, and Tevesz (1998) assigned an aragonitic mineralogy for all shell layers to the family Cassianellidae. Previously, Carter (1990b) noted that some species of Cassianella [e.g., C. beyrichi Bittner, 1895, or C. inaequiradiata (Schafhäutl, 1852)] have calcite in the outer shell layer. Cassianella is the only genus of this family for which there are studies of the mineralogy and shell microstructure. Outer shell layer: calcite or aragonite (prismatic). Inner shell layer: aragonite (prismatic).

  • Genus BURCKHARDTIA Freeh, 1907, p. 334

  • Type species.—Cassianella (Burckhardtia) boesei Freeh, 1907, p. 334.

  • Remarks.—According to Alencaster de Cserna (1961), the type species was first referred to ?Pterinea by Burckhardt and Scalia (1905).

  • Frech (1907) argued that this species was better included in Cassianella on the basis of its characteristics, and he named the subgenus Burckhardtia. But Alencaster de Cserna (1961) suggested that this species is more related to Myophoria Bronn, 1835 in 1834—1838, than to Cassianella Beyrich, 1862, and she included it in the first genus. Following Cox and others (1969), we regard it as a separate genus within the family Cassianellidae due to the presence of obtuse wings, a feature not known among myophorids.

  • Stratigraphic range.—Upper Triassic (Carnian) (Freeh, 1907). Freeh (1907) described the genus from Carnian beds of Zacatecas (Mexico), and it appears to be endemic in this area and restricted to this age (Burckhardt & Scalia, 1905; Diener, 1923; Alencaster de Cserna, 1961; Cox & others, 1969, Hallam, 1981; Kobayashi & Tamura, 1983a; Barboza-Gudino, Tristán-González, & Torres-Hernández, 1990; Sepkoski, 2002).

  • Paleogeographic distribution.—Circumpacific (Fig. 15).

  • Circumpacific domain: Late Triassic: Carnian of Mexico (Burckhardt & Scalia, 1905; Freeh, 1907; Alencaster de Cserna, 1961; Barboza-Gudino, Tristán-González, & Torres-Hernández, 1990).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Burckhardtia probably had a mode of life similar to Cassianella, but considering that it is almost subequivalve, a semi-infaunal mode of life, similar to Hoernesia, would perhaps be more likely.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 207; Carter, Barrera, & Tevesz, 1998). Data provided for family Cassianellidae. There are no studies on the shell of Burckhardtia (see Cassianella mineralogy, p. 46). Outer shell layer: calcite or aragonite (prismatic). Inner shell layer: aragonite (prismatic).

  • Figure 15.

    Paleogeographical distribution of Cassianellidae (Cassianella, Burckhardtia, Hoernesiella, Lilangina, Reubenia, Septihoernesia). 1, Middle Triassic; 2, Late Triassic.

    f15_01.jpg

    Genus HOERNESIELLA Ichikawa, 1958, p. 195

  • ex Gugenberger, 1935, p. 250

  • Type species.—Floernesiella horrida Gugenberger, 1935, p. 250.

  • Remarks.—Gugenberger did not designate a type species for his genus Hoernesiella. Ichikawa (1958, p. 195) designated Hoernesiella horrida as type species, and he claimed the generic authorship under Article 25 c 3 of ICZN (1999). Years later, Cox in Cox and others (1969, p. 312), surely without knowledge of Ichikawa's (1958) paper, noticed the lack of type species, and designated another type species for Hoernesiella: H. carinthiaca Gugenberger, 1935, p. 250, also claiming the generic name authorship (see Stenzel, 1971, p. 1215). Vokes (1980) attributed the authorship to Ichikawa (1958) by priority of type species designation, and this approach is followed here.

  • Stratigraphic range.—Upper Triassic (Carnian) (Cox & others, 1969). Cox and others (1969), Stenzel (1971), Hallam (1981), and Sepkoski (2002) assigned it a Carnian range. It was not possible to find more information about this genus.

  • Paleogeographic distribution.—western Tethys (Fig. 15).

  • Tethys domain: Late Triassic: Carnian of Carinthia (Austria) (Ichikawa, 1958; Cox & others, 1969).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Similar to Cassianella.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 207; Carter, Barrera, & Tevesz, 1998). Data provided for family Cassianellidae. There are no specific studies on the shell of Hoernesiella (see Cassianella mineralogy, p. 46). Outer shell layer: calcite or aragonite (prismatic). Inner shell layer: aragonite (prismatic).

  • Genus LILANGINA Diener, 1908, p. 62

  • Type species.—Lilangina nobilis Diener, 1908, p. 62.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Cox & others, 1969; Komatsu, Huyen, & Huu, 2010). All sources checked assigned Lilangina to the Carnian (Diener, 1923; Cox & others, 1969; Hallam, 1981; Kobayashi & Tamura, 1983a). However, recently, Komatsu, Huyen, and Huu (2010) reported it from the Anisian and Ladinian.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 15).

  • Tethys domain: Middle Triassic: Anisian—Ladinian of northern Vietnam (Komatsu, Huyen, & Huu, 2010); Late Triassic: Carnian of Kashmir (Diener, 1923; Cox & others, 1969; Kobayashi & Tamura, 1983a), China (Wen & others, 1976; Kobayashi & Tamura, 1983a; Sha, Chen, & Qi, 1990).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Similar to Cassianella.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 207; Carter, Barrera, & Tevesz, 1998). Data provided for family Cassianellidae. There are no specific studies on the shell of Lilangina (see Cassianella mineralogy, p. 46). Outer shell layer: calcite or aragonite (prismatic). Inner shell layer: aragonite (prismatic).

  • Genus REUBENIA Cox, 1924, p. 61

  • Type species.—Reubenia hesbanensis Cox, 1924, p. 63.

  • Stratigraphic range.—Upper Triassic (Carnian) (Cox, 1924). Cox (1924) described Reubenia from the Carnian beds of Jordan, including two species, the type species and Reubenia attenuata Cox, 1924. All reviewed literature (Kutassy, 1931; Cox & others, 1969; Hallam, 1981; Sepkoski, 2002) assigned it the same stratigraphic range.

  • Paleogeographic distribution.—western Tethys (Fig. 15).

  • Tethys domain: Late Triassic: Carnian of Jordan (Cox, 1924).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Similar to Cassianella.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 207; Carter, Barrera, & Tevesz, 1998). Data provided for family Cassianellidae. There are no specific studies on the shell of Reubenia (see Cassianella mineralogy, p. 46). Outer shell layer: calcite or aragonite (prismatic). Middle shell layer: aragonite (nacreous). Inner shell layer: aragonite (prismatic).

  • Genus SEPTIHOERNESIA Cox, 1964, p. 40

  • Type species.—Gervillia johannisaustriae Klipstein, 1845 in 1843–1845, p. 249.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Carnian) (Allasinaz, 1966; Tamura, 1990). Cox and others (1969) assigned it a Triassic range, without further comments. Sepkoski (2002) assigned it a Triassic (lower Anisian—Carnian) range, allegedly using Hallam (1981) as data source, but Hallam only mentioned it from Ladinian and Carnian times. The published records indicate that the genus was only present in these two Triassic stages.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 15).

  • Tethys domain: Middle Triassic: Ladinian of Malaysia (Tamura & others, 1975); Late Triassic: Carnian of Italy (Allasinaz, 1966; Fürsich & Wendt, 1977), Spain (Martín-Algarra, Solé de Porta, & Márquez-Aliaga, 1995), Malaysia (Tamura & others, 1975).

  • Circumpacific domain: Middle Triassic: Ladinian of Japan (Tamura, 1990); Late Triassic: Carnian of Japan (Tamura, 1990).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Similar to Cassianella.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 207; Carter, Barrera, & Tevesz, 1998). There are no studies on the shell of Septihoernesia (see Cassianella mineralogy, p. 46). Outer shell layer: calcite or aragonite (prismatic). Inner shell layer: aragonite (prismatic).

  • Family DATTIDAE Healey, 1908
    Genus DATTA Healey, 1908, p. 63

  • Type species.—Datta oscillaris Healey, 1908, p. 63.

  • Stratigraphic range.—Upper Triassic (Rhaetian) (Healey, 1908). Healey (1908) described the genus from Rhaetian beds of Burma, and Cox and others (1969) repeated these data. Kobayashi and Tamura (1983a) recorded Datta from several Upper Triassic localities but did not mention stages or the original data source. The statement in Damborenea (2002b, p. 56): “… During the Jurassic and Lower Cretaceous, most genera of Anomiidae, Burmesiidae, Ceratomyopsidae, Cuspidariidae [Dattidae] Diceratidae . …” is an error, and there are no records of Datta from the Jurassic.

  • Paleogeographic distribution.—Southern Tethys (Fig. 16). The original material is from Burma (Healey, 1908). Later, Kobayashi and Tamura (1983a) also reported the genus from the Late Triassic of Kashmir and Yunnan (China), but they did not indicate the original source, and no information related to these records was found.

  • Paleoautoecology.—B, E, S, ?, ?. It is difficult to assign a mode of life to this genus since the only information available is from a left valve mold with a possible chondrophore. The shell morphological features suggest it was probably epifaunal.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 205). Data provided for superfamily Pterioidea. There are no specific studies on Datta shell. Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (nacreous).

  • Family ISOGNOMONIDAE Woodring, 1925

  • It is often difficult to distinguish between Isognomonidae and Bakevelliidae; good examples are the genera Isognomon (Mytiloperna) von Ihering, 1903, and Gervilleioperna Krumbeck, 1923b, about which there is no agreement among different authors (see discussions for these taxa, below and p. 45). It is quite evident that these two families are phylogenetically related, and consequently setting limits is complicated. A revision of their diagnostic features is needed to establish a consensus. There are also certain difficulties in distinguishing between Inoceramidae and Isognomonidae (see Crampton, 1988).

  • Genus ISOGNOMON [Lightfoot, 1786], p. 41, 52

  • Lightfoot proposed the name in an anonymous catalogue (1786, authorship determined by Dance, 1962, see also Kay, 1965) spelling the name both as Isognoma and Isognomon, and later Dall, Bartsch, and Rehder (1938, p. 61–62) regarded Isognomon as the original spelling and Isognoma as a misspelling (first revisers action according to Coan, Valentich Scott, & Bernard, 2000, p. 196).

  • Type species.—Ostrea isognomon Linnaeus, 1764, p. 533 (= Ostrea isognomum in Linné, 1758), by absolute tautonymy (see discussion in Rehder, 1967, p. 6, and Coan, Valentich Scott, & Bernard, 2000, p. 196). This differs from the interpretation by Cox (in Cox and others, 1969, p. 322), which was followed by most authors.

  • Remarks.—According to Cox and others (1969), there are two subgenera of Isognomon within our interval of study, I. (Isognomon) (but see below) and I. (Mytiloperna). However, some authors noted that probably the latter is more related to bakevelliids than to isognomonids. Mytiloperna was described by H. von Ihering (1903) as a genus based in Perna americana Forbes; Cox (1940) demoted it to a subgenus of Isognomon Lightfoot, 1786, a position maintained in Cox and others (1969) (see Accorsi-Benini & Broglio-Loriga, 1975, for details). There are several reasons to consider that Mytiloperna does not fit into the Isognomonidae. One is the shell microstructure (Broglio-Loriga & Posenato, 1996). Another is that adults had a hinge with teeth, a feature of Bakevelliidae and not of Isognomonidae, which were toothless in the adult stage (Seilacher, 1984; Aberhan, 1998a). However, while pending a good revision of the family, it is advisable to treat Mytiloperna as an isognomonid (Jaitly, Fiirsich, & Heinze, 1995). Additionally, due to a misinterpretation about the correct way of fixation of the type species of Isognomon (see above, and IZCN, 1999, Art. 68.1 and 68.4), most Mesozoic species should be referred to Isognomon (Melina) Retzius, 1788, p. 22, and not to Isognomon (Isognomon), a fact overlooked by most authors, even by those who accepted I. sognomon as type of the genus..

  • Stratigraphic range.—Upper Triassic (Carnian)—Holocene (Cox & others, 1969). Cox and others (1969) assigned an Upper Triassic to Holocene range to Isognomon (Isognomon) and an Lower Jurassic to Upper Jurassic range to Isognomon (Mytiloperna). Linck (1972) reported the last subgenus from the Carnian, but he included in Mytiloperna (considered at genus level) some modioliform specimens somewhat different from the typical ones. Today there are numerous species living in tropical seas (Beesley, Ross, & Wells, 1998).

  • Paleogeographic distribution.—Tethys (Fig. 16). During other intervals of geological time, the genus also lived in Circumpacific and Austral regions, especially during the Pliensbachian (see e.g., Damborenea, 1987b; Broglio-Loriga & Posenato, 1996; Aberhan & Fürsich, 1997; Aberhan 1994a, 1998a; Liu, 1999; Fraser, Bottjer, & Fischer, 2004). However, during the temporal interval under consideration, it was only known from the Tethys domain. Holocene species of Isognomon are mainly distributed in tropical seas.

  • Tethys domain; Late Triassic; Carnian of China (Sha, Chen, & Qi, 1990), Germany (Linck, 1972), southern Italian Alps (Fürsich & Wendt, 1977), Italy (Gelati & Allasinaz, 1964); Norian of Austria (Tichy, 1975), Italy (Terranini, 1958); late Norian of southern China (J. Chen, 1982a); Norian—Rhaetian of Iran, Burma, and Vietnam (Hautmann, 2001b; Fürsich & Hautmann, 2005); Rhaetian of Alps (Italy) (Pozzi, Gelati, & Allasinaz, 1962); Early Jurassic; Hettangian of Japan (Kondo & others, 2006), Europe and northeastern Asia (Hallam, 1977); Hettangian—Toarcian of Japan (Hayami, 1957a, 1975); Sinemurian of Morocco (Liu, 1995), northwestern Europe (Hallam, 1987).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. A semi-infaunal endobyssate mode of life seems likely for most Mesozoic species, although some Recent species live epifaunally (S. M. Stanley, 1970, 1972). This disparity in mode of life can be recognized by differences in shell morphology. Living species are often very inequivalve, unlike Mesozoic species, which were equivalve or subequivalve (Hayami, 1957a); there are also differences in shell thickness, the umbonal part being thicker than the ventral part in Mesozoic species (see Fürsich, 1980; Seilacher, 1984; Broglio-Loriga & Posenato, 1996; Fraser, Bottjer, & Fischer, 2004).

  • Fürsich (1980) analyzed some of the fossil species and observed that, if only shell characters were taken into account, his interpretations were wrong and not viable when he could contrast these results with direct observation of individuals found in life position in the field. All fossil species studied in his work of l980 seem to support a semi-infaunal endobyssate mode of life. Furthermore, fossil species are often found forming groups, and thus they were interpreted as gregarious (Fürsich, 1982; Damborenea, 1987b).

  • With regard to I. (Mytiloperna), several authors studied its morphology in relation to its mode of life (e.g., Seilacher, 1984; Broglio-Loriga & Posenato, 1996; Fraser, Bottjer, & Fischer, 2004). These last two papers distinguished several Mytiloperna morphotypes with different life habit interpretations, ranging from epifaunal to semi-infaunal.

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 339). Accorsi-Benini and Broglio-Loriga (1975) and Broglio-Loriga and Posenato (1996) described a fibrous microstructure in the inner shell layer of Mytiloperna sp. specimens. Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Genus LEPROCONCHA Giebel, 1856, p. 67

  • Type species.—Leproconcha paradoxa Giebel, 1856, p. 67.

  • Remarks.—When Giebel (1856) described the genus, he did not mention its systematic relations, although he indicated that it was intermediate between Ostreacea and Malleacea. Nevertheless, Cox and others (1969) decided to include it with doubts into the Isognomonidae. Looking at the drawings in Giebel (1856, pl. 2,10,13), we can understand why this assignation was more than doubtful. We assume that the ligament pits were the key feature to include Leproconcha in this family, but, unlike the rest of isgnonomonids, it shows an almost equivalve shell and an ostreid external appearance. Lacking any better solution, we follow Cox and others (1969), even knowing it is very unlikely that this genus belongs to this family.

  • Stratigraphic range.—Middle Triassic (Giebel, 1856). Giebel (1856) described Leproconcha from Muschelkalk of the Germanic Basin. Diener (1923), Kutassy (1931), Cox and others (1969), and Kobayashi and Tamura (1983a) repeated these data, and no further information was found.

  • Paleogeographic distribution.—western Tethys (Fig. 16).

  • Tethys domain: Middle Triassic: Muschelkalk of Germany (Giebel, 1856).

  • Paleoautoecology.—B, E, S, ?, ?. Probably epifaunal.

  • Mineralogy.—Unknown. There is no information about mineralogy or microstructure of Leproconcha shell. We cannot assign it the mineralogy predominant in the family because we have serious doubts about the family assignation of this genus.

  • Genus WAAGENOPERNA Tokuyama, 1959a, p. 151

  • Type species.—Edentula lateplanata Waagen, 1907, p. 97.

  • Remarks.—Waagenoperna Tokuyama, 1959a was proposed to replace Edentula Waagen, 1907 (non Nitzsch, 1820), and Edentula lateplanata Waagen, 1907, was designated as type species by Tokuyama (1959a). Some years earlier, Cox (1954) had proposed the name Cuneigervillia also to replace Edentula, choosing Gervillia hagenowii Dunker, 1846, as the type species. When Tokuyama (1959a) compared the two type species, he noticed that while Gervillia hagenowii is a bakevelliid (in fact, Cox, 1954, included Cuneigervillia in the family Bakevelliidae), Edentula lateplanata is an isognomonid, like other species attributed to Edentula (E. triangularis Kobayashi & Ichikawa, 1952). Lower Jurassic species also referred to Cuneigervillia by Cox clearly showed that this genus was not objectively the same as Edentula (in fact, they have different type species), and he decided to maintain both names, Cuneigervillia and Waagenoperna (=Edentula), which was followed by Cox and others (1969).

  • Nakazawa and Newell (1968) proposed a new subgenus within Waagenoperna, W. (Permoperna), and although some authors (Z. Fang, 1982) treated Permoperna at generic level, the original rank is here retained because it does not present substantial differences from Waagenoperna s.s.

  • Tëmkin (2006, p. 270) erroneously indicated that Waagenoperna was based on W. triangularis (Kobayashi & Ichikawa, 1952).

  • Stratigraphic range.—lower Permian (Sakmarian)—Upper Triassic (upper Norian) (Hayami & Kase, 1977; J. Chen, 1982a). Cox and others (1969) assigned it a middle Permian—Upper Triassic range. The stratigraphic range should be extended back, since Nakazawa and Newell (1968) reported Waagenoperna (Permoperna) from the lower Permian (Sakmarian). Sepkoski's (2002) range starts from the Guadalupian, which is odd considering that he took his data from Hayami and Kase (1977) and Skelton and Benton (1993), who indicated Sakmarian as the first record. Regarding the upper extension of this genus, J. Chen (1982a, p. 303) quoted Waagenoperna from the upper Norian of southern China, indicating that the association to which it belonged is “the uppermost Triassic bivalve zone in this region.” There are several reports from Hettangian brackish environments of southern China (Sha & Jiang, 2004; Jiang, Sha, & Pan, 2008), although none was corroborated by illustrations or descriptions of the material.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 16).

  • Tethys domain: Late Triassic: Carnian of southern Alps (Broili, 1904; Tokuyama, 1959a), southern China (Gu & others, 1980); late Norian of China (J. Chen, 1982a).

  • Circumpacific domain: late Permian: Japan (Nakazawa & Newell, 1968; Hayami, 1975); Middle Triassic: Ladinian of Japan (Tokuyama, 1959a; Hayami, 1975); Late Triassic: Carnian—Norian of Japan (Tokuyama, 1959a; Hayami, 1975).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Although Waagenoperna had a mytiliform shell and most isognomonids were interpreted as epifaunal bivalves, Waagenoperna was thought to be a semi-infaunal endobyssate bivalve, similar to Pinna and some pterineids (S. M. Stanley, 1972). This author relied on morphological evidence, such as the strongly prosocline, slightly inflated, subequivalve shell and the presence of an anterior lobe, features not shared with any other member of the family Isognomonidae.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 209). There are no data about the Waagenoperna shell. Information provided for family Isognomonidae. Outer shell layer: calci te (simple prismatic). Middle and inner shell layers: aragonite (nacreous).

  • Family POSIDONIIDAE Neumayr, 1891

  • The Posidoniidae family members are hardly distinguishable from each other because one of the main diagnostic features is the ligament area, and this is only preserved in exceptional cases. Due to the usually very thin shell, all internal shell characters are frequently destroyed during diagenesis. Waller (in Waller & Stanley, 2005) gathered the families Posidoniidae and Halobiidae Kittl, 1912, in the superfamily Posidonioidea Freeh, 1909. This arrangement is probably more appropriate than the one followed here, but according to Amler (1999), we consider the first family in the superfamily to be Pterioidea Gray 1847, and the second one to be Halobioidea H. J. Campbell, 1994.

  • Genus BOSITRA De Gregorio, 1886, p. 11

  • Type species.—Posidonia ornati Quenstedt, 1851 in 1851—1852, p. 501.

  • Remarks.—Following Waller (in Waller & Stanley, 2005), we regard Posidonia Bronn, 1828, as a Paleozoic genus, referring described species from Lower and Middle Triassic to Bositra. We consider Peribositria Kurushin & Trushchelev, 1989, to be a synonym of Bositra (see discussion for Peribositria in Genera not Included, p. 167).

  • Stratigraphic range.—Lower Triassic (lower Olenekian)—Middle Jurassic (lower Oxfordian) (Waller & Stanley, 2005). Cox and others (1969) assigned it a Jurassic range, but after Waller and Stanley (2005) emended the genus and they transferred species traditionally included in Posidonia from Lower and Middle Triassic, the range was extended back to the Triassic. The problem in the differentiation of both genera is that the main diagnostic characters are in the ligament area, as well as other internal structures, which are often destroyed during diagenesis (Waller in Waller & Stanley, 2005). Fürsich and Werner (1988) reported Bositra from the Upper Jurassic (Kimmeridgian) of Portugal, but their specimens were referred to this genus with some hesitation since the ligament area is not preserved.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 17). During the Early Triassic, Bositra was distributed mainly in the Boreal domain, extending over the Tethys and Circumpacific domains during the Middle Triassic, to become virtually cosmopolitan during the Early Jurassic (Waller & Stanley, 2005), especially during the Toarcian (Damborenea, 1987b; Aberhan, 1994a, 1998a; Monari, 1994; Liu, 1995; Harries & Little, 1999; Gahr, 2002), coinciding with the peak of early Toarcian extinction. We did not take into account the mention in Waterhouse (2000), because Waller and Stanley (2005) affirm the specimens are more clariids than posidoniids.

  • Tethys domain; Middle Triassic; Slovenia (Jurkovsek, 1984); Anisian of China (Wen & others, 1976; Ling, 1988; Komatsu, Akasaki, & others, 2004a; J. Chen & Stiller, 2007), western Carpathians (Slovakia) (Kochanová, 1985); Anisian—Ladinian of Vietnam (Vu Khuc & Huyen, 1998); Ladinian of Spain (Márquez-Aliaga, 1983, 1985; Márquez-Aliaga & Ros, 2003); Late Triassic: Carnian of China (Wen & others, 1976), Italy (Fürsich & Wendt, 1977); Norian of China (Sha, Chen, & Qi, 1990).

  • Circumpacific domain; Middle Triassic; Anisian of Japan (Hayami, 1975), of Nevada (United States) (Waller & Stanley, 2005).

  • Boreal domain; Early Triassic; Siberia (Kiparisova, 1938; Dagys & Kurushin, 1985), Arctic Archipelago (Canada) (Tozer, 1961, 1962, 1970).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Bositra was interpreted as a pseudoplanktonic bivalve (S. M. Stanley, 1972) or as nektoplanktonic (Jefferies & Minton, 1965; Hayami, 1969a; Duff, 1975), according to its distribution and morphological characteristics. Other authors rejected these interpretations considering the habit of species assigned to Bositra as benthic (M. A. Conti & Monari, 1992; Etter, 1996).

  • Etter (1996) did a comprehensive study reviewing all possible modes of life ever attributed to Bositra, demonstrating that a benthic mode of life is entirely plausible and providing arguments to reject the other two options. Since a byssal notch is not observed, a reclined mode of life would have been the most likely (Waller & Stanley, 2005). The reason for its frequent presence in oxygenpoor sedimentary environments should more probably be related to an opportunistic behavior than to a pseudoplanktonic mode of life (Etter, 1996). An updated discussion on the mode of life for Bositra was provided by Caswell, Coe, and Cohen (2009, and see references therein).

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 340; Waller & Stanley, 2005). Outer shell layer: calci te (homogeneous-prismatic). Inner shell layer: aragonite (nacreous).

  • Figure 16.

    Paleogeographical distribution of Isognomonidae (Isognomon, Leproconcha, Waagenoperna) and Dattidae (Datta). 1, late Permian; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f16_01.jpg

    Genus AMONOTIS Kittl, 1904, p. 736

  • Type species.—Amonotis cancellaria Kittl, 1904, p. 736.

  • Stratigraphic range.—Upper Triassic (Carnian). Amonotis was reported from Carnian beds (Cox & others, 1969; C. Chen & Yu, 1976; Sha, Chen, & Qi, 1990) and apparently also from the Norian, although Norian records lack illustrations or they were dubiously assigned to the genus (Niu, Xu, & Ma, 2003; Tang & others, 2007).

  • Paleogeographic distribution.—Tethys (Fig. 17). Amonotis was found both in western and eastern Tethys, although some authors (Hallam, 1981; Metwally, 1993) only included European occurrences in their compilations.

  • Tethys domain; Late Triassic; Carnian of Yugoslavia (Cox & others, 1969), China (C. Chen & Yu, 1976; Sha, Chen, & Qi, 1990).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to S. M. Stanley (1972), almost all posidoniids were epibyssate bivalves, though almost none of the genera shows a sinus or byssal notch, and some of them could be pseudoplanktonic, although there is no evidence that Amonotis was one of them. Therefore, we consider Amonotis as to be an epibyssate bivalve in agreement with Sha, Chen, and Qi (1990), but the possibility of a reclined habit similar to Bositra cannot be ruled out.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 211). Data provided for family Posidoniidae. We lack information about the shell of Amonotis. Outer shell layer: calci te (prismatic-homogeneous). Inner shell layer: aragonite (nacreous).

  • Genus VELDIDENELLA Alma, 1925, p. 118

  • Type species.—Veldidenella dieneri Alma, 1925, p. 118.

  • Stratigraphic range.—Middle Triassic (upper Anisian—upper Ladinian) (Kochanová, 1985). Cox and others (1969) assigned it a Upper Triassic range, and both Sepkoski (2002) and other compilation papers (e.g., Metwally, 1993) repeated this information. But according to the information published on this monospecific genus, these data appear to be wrong. According to Kutassy (1931), Alma in 1925 described the type species of this genus from Anisian beds of the northern Alps. Tichy (1970), in his catalog of type specimens housed at the Museum of Natural History in Vienna, also indicated Anisian as the age of the type species. Subsequently, Kochanová (1985) reported Veldidenella dieneri from Anisian beds of the western Carpathians and from upper Ladinian beds of the southern Austrian Alps.

  • Paleogeographic distribution.—western Tethys (Fig. 17).

  • Tethys domain; Middle Triassic; Anisian of northern Alps (Austria) (Kutassy, 1931), Carpathians (Slovakia) (Kochanová, 1985); Ladinian of northern Alps (Austria) (Kochanová, 1985).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Similar to Amonotis.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 211). There are no data about Veldidenella mineralogy or shell microstructure. Data provided for the family Posidoniidae. Outer shell layer: calcite (prismatic-homogeneous). Inner shell layer: aragonite (nacreous).

  • Genus CAENODIOTIS Monari, 1994, p. 171

  • nom. nov. pro Diotis Simonelli, 1884, p. 125, non Schmarda, 1859, p. 5

  • Type species.—Posidonomya janus Meneghini, 1853, p. 27

  • Remarks.—Damborenea (1987b, p. 191) noticed that the name Diotis was used previously for a group of worms (Diotis Schmarda, 1859). Years later, Monari (1994) proposed the name Caenodiotis to replace Diotis Simonelli, 1884, in accordance with Article 52 of ICZN (1999). Following Cox and others (1969) and Monari (1994), we include Caenodiotis in Posidoniidae, although given its probable relations to Posidonotis (Damborenea, 1987b), it could perhaps be included in Entoliidae.

  • Stratigraphic range.—Lower Jurassic (Sinemurian—Pliensbachian) (Monari, personal communication, 2007). According to Cox and others (1969), Diotis was distributed during the early and middle Early Jurassic, but we could not check exactly which stages. Monari (1994) noted its presence from the Pliensbachian in several Italian localities. He also found it in the Sinemurian of the Umbria-Marche region (Monari, personal communication, 2007). We assign the range Sinemurian—Pliensbachian to this genus, until we can determine the age of the units widely referred to as lower Liassic by Cox and others (1969).

  • Paleogeographic distribution.—western Tethys (Fig. 17). During the Early Jurassic, especially during the Pliensbachian, the genus was distributed in Italy (Monari, 1994), Hungary (Szente, 1990), and Spain (Jiménez de Cisneros, 1923). During the time interval here analized, we only consider the Sinemurian records.

  • Tethys domain: Early Jurassic: Sinemurian of Italy (Monari, personal communication, 2007).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Similar to Amonotis.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 211). There are no data about the Caenodiotis shell. Data provided for family Posidoniidae. Outer shell layer: calcite (prismatic-homogeneous). Inner shell layer: aragonite (nacreous).

  • Genus STEINMANNIA Fischer, 1886 in 1880—1887, p. 960

  • nom. nov. pro Aulacomya Steinmann, 1881, p. 259, non Mörch, 1853, p. 53

  • Type species.—Posidonia bronnii Voltz in Zieten, 1833 in 1830– 1833, p. 72.

  • Remarks.—Steinmannia is very similar morphologically to Bositra De Gregorio, 1886, and Posidonia Bronn, 1828, and the observation of the ligament type is key to discriminating between these genera (multivincular in Steinmannia, alivincular in Bositra, and duplivincular in Posidonia), but its preservation is not common (Waller in Waller & Stanley, 2005). Although Guillaume (1928) and later authors (e.g., Cox & others, 1969; Milova, 1988) included Steinmannia in the Inoceramidae due to the ligament type, Waller (in Waller & Stanley, 2005) thought the ligament of Steinmannia was not of the inoceramid type: “the relatively few ligament pits on the ligament area of Steinmannia bronni (three or four according to Guillaume, 1928, p. 221; three to five according to Milova, 1988, p. 63, pl. 2,1–3) maybe a phylogenetically independent multiplication of the simple alivincular ligament of Bositra possibly functionally associated with increase in size and convexity.“ Following Waller (in Waller & Stanley, 2005), we consider Steinmannia more related to Posidoniidae than Inoceramidae. Some authors included the type species of Steinmannia in Bositra (e.g., Hallam, 1976, 1987; Caswell, Coe, & Cohen, 2009). Multisidonia Polubotko, 1992, p. 60 (type species M. omolonensis Polubotko, 1992, p. 60), distinguished by a greater number of ligamen tal pits, is a possible synonym.

  • Stratigraphic range.—Lower Jurassic (upper Sinemurian—lower Toarcian) (Guillaume, 1928; Milova, 1988). Cox and others (1969) assigned it a Toarcian range, but Milova (1988) reported a new species, Steinmannia viligaensis Milova, from upper Sinemurian beds (also another from the Pliensbachian, Steinmannia alikiensis Milova, 1988), and the type of Multisidonia is also late Sinemurian in age (Polubotko, 1992). Sepkoski (2002) did not consider this genus.

  • Paleogeographic distribution.—Boreal (Fig. 17). During the Early Jurassic, especially in the Toarcian, the genus was distributed in the Tethys domain (France, England, Germany, Switzerland) (Guillaume, 1928).

  • Boreal domain: Early Jurassic: Sinemurian of northeastern Russia (Milova, 1988).

  • Paleoautoecology.—B, E, S, Un, Sed; R. See mode of life for Bositra (p. 50).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 211). There are no data about the shell of Steinmannia. Data provided for family Posidoniidae. Outer shell layer: calcite (prismatic-homogeneous). Inner shell layer: aragonite (nacreous).

  • Genus ELLESMERELLA Waterhouse, 2008, p. 172

  • Type species.—Posidonia aranea Tozer, 1961, p. 102.

  • Remarks.—Waterhouse (2008) proposed Ellesmerella based on P. aranea, included it in the family Aulacomyellidae Ichikawa, 1958, and considered it to be related to Bositra. McRoberts (2010) suggested it could be better placed into Posidoniidae or Halobiidae. Provisionally, we include Ellesmerella in the Posidoniidae.

  • Stratigraphic range.—Lower Triassic (upper Olenekian) (Tozer, 1961). The monospecific genus Ellesmerella was only reported from the Olenekian stage (Tozer, 1961, 1962, 1970; Vozin & Tikhomirova, 1964; Tozer & Parker, 1968; Waterhouse, 2008; McRoberts, 2010). It has a very short stratigraphical range (uppermost Olenekian) (McRoberts, 2010).

  • Paleogeographic distribution.—Boreal (Fig. 17).

  • Boreal domain: Early Triassic: late Olenekian of Arctic Archipelago (Canada) (Tozer, 1961), Svalbard (Norway) (Tozer & Parker, 1968), British Columbia (Tozer, 1962, 1970), northeastern Siberia (Vozin & Tikhomirova, 1964).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Similar to Bositra.

  • Mineralogy.—Bimineralic (Carter, 1990a). There are no data about the shell of Ellesmerella. Data provided for family Posidoniidae and/ or Halobiidae.

  • Superfamily PINNOIDEA Leach, 1819
    Family PINNIDAE Leach, 1819

  • In our study interval, there are two genera belonging to Pinnidae: Pinna Linnaeus, 1758, and Atrina Gray, 1842, p. 83 [1840, p. 151, nom. nud.]. These two genera are morphologically very similar in their juvenile stages, but adults are differentiated mainly by the presence of a median shell carina, which is associated with the separation of the internal nacreous layer into two lobes in Pinna and is absent in Atrina (Cox & others, 1969; Waller & Stanley, 2005). Cox and others (1969) assigned a Carboniferous—Holocene range to Pinna (Pinna) and a Middle Jurassic—Holocene range to Atrina. However, many specimens assigned to Pinna (Pinna) from beds older than Middle Jurassic do not have this median carina, and thus they should probably be referred to Atrina or some Paleozoic genera (Pteronites M'Coy, 1844, Aviculopinna Meek, 1864, or Meekopinna Yancey, 1978) (see Waller & Stanley, 2005, p. 29). In the absence of a review on this subject, we assign provisional stratigraphic ranges for both genera.

  • Genus PINNA Linnaeus, 1758, p. 707

  • Type species.—Pinna rudis Linnaeus, 1758, p. 707.

  • Stratigraphic range.—?Lower Triassic—Holocene (Nakazawa, 1961). Although, as already mentioned, Cox and others (1969) assigned it a range from the Carboniferous, we could not locate any record of specimens attributed to this age except in the Treatise. A specimen of Pinna (Pinna) costata Phillips from the Carboniferous of Belgium was figured in Cox and others (1969, p. 282), but this specimen does not show the typical carina, and therefore it is not supposed to belong to Pinna (Waller & Stanley, 2005). R. Zhang and Yan (1993) reported the genus from the Carboniferous, but they did not illustrate or describe the material. The oldest positive records are from the Lower Triassic. Nakazawa (1961) figured Pinna muikadaniensis Nakazawa, 1961 (p. 267; plate 13,14), and, although in the description he did not mention the median carina, he said: “… parting mediate distinct but weak in the umbonal half and obsolete in the rear part, deviating towards the an tero-ventral side …” and the figure shows evidence of a true carina. Seguí (1999, p. 21, fig. 1), in the description of his specimen of Pinna bascoi Seguí, 1999, from Ladinian of Spain, said: “There is an edge signal that starting from the apex disappears at about 2/3 of the height. This edge divides the shell into two parts.” This edge can be seen in his figures and seems to correspond with the carina. We doubtfully consider Nakazawa's (1961) Lower Triassic record as valid, since the material is not well preserved and we cannot be sure that it actually belongs to Pinna.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 18). Although Pinna had a cosmopolitan distribution during our study interval, Recent species are restricted to tropical and subtropical seas (Cox & others, 1969). No records were located from the Boreal domain.

  • Tethys domain; Early Triassic: China (F. Wu, 1985); Middle Triassic: Ladinian of Spain (Seguíacute;, 1999); Late Triassic: southern China (Gou, 1993); Carnian of Slovenia (Jelen, 1988), southern Alps (Italy) (Fürsich & Wendt, 1977), Lombardy (Italy) (Allasinaz, 1964, 1966), Germany (Linck, 1972); Norian of Australia (Grant-Mackie, 1994); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Burma (Healey, 1908), Alps (Austria) (Winkler, 1861), Tibet (China) (J. Yin & McRoberts, 2006), Pamir (Afghanistan) (Polubotko, Payevskaya, & Repin, 2001), Hungary (Vörös, 1981), Italy (Allasinaz, 1962; Sirna, 1968); Early Jurassic: Hettangian of Tibet (China) (J. Yin & McRoberts, 2006), England and Morocco (Liu, 1995), Italy (Sirna, 1968), France (Martin, 1860); Sinemurian of Portugal, Spain, England, France, and Morocco (Liu, 1995).

  • Austral domain: Late Triassic: Carnian of New Zealand (Trechmann, 1918; Marwick, 1953); Early Jurassic: Hettangian—Sinemurian of Argentina (Damborenea, 1996a; Damborenea & Manceñido, 2005b); Sinemurian of Argentina (Damborenea & Lanes, 2007).

  • Circumpacific domain: Early Triassic: Japan (Nakazawa, 1961; Hayami, 1975); Late Triassic: Norian of Chile (Hayami, Maeda, & Ruiz-Fuller, 1977); Early Jurassic: Sinemurian of Canada (Aberhan, 1998a).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Depending on the species, Pinna currently lives more or less with the anterior half of the shell buried in the sediment as endobyssate, with a strong byssus attached to fragments of rocks or other objects, such as sea grass roots (García-March, 2005), although some were found epibyssate on hard substrates (S. M. Stanley, 1970). Regarding fossil species, there are many examples of Pinna in upright position, similar to living species (e.g., Fürsich, 1980, 1982; Damborenea, 1987a). It is rare to find complete fossil specimens; only the anterior parts, which are buried in life, are usually found. More detailed information about its mode of life can be found in Yonge (1953) and Seilacher (1984), among many others.

  • Mineralogy.—Bimineralic (Yonge, 1953; Carter, 1990a; García-March, 2005; García-March, Márquez-Aliaga, & Carter, 2008). Outer shell layer: calci te (prismatic simple). Inner shell layer: aragonite (nacreous).

  • Genus ATRINA Gray, 1842, p. 83

  • Gray, 1840, p. 151, nom. nud.

  • Type species.—Pinna nigra Dillwyn, 1817, p. 325.

  • Stratigraphic range.—Middle Triassic (Anisian)—Holocene (Stiller, personal communication, 2008). Although Cox and others (1969) assigned it a range from the Middle Jurassic, Waller (in Waller & Stanley, 2005) reported Atrina from the Ladinian. Also Stiller, in his doctoral thesis (Stiller, personal communication, 2008), reported it from the Anisian. Although, as noted, it may have appeared before, we will take this well-documented record as its first appearance. In addition, Waller and Stanley (2005, p. 29–30) noted that Carboniferous Pinnidae could possibly be referable to Atrina and not to Pinna.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 18). Although in the past Atrina was regarded as a cosmopolitan genus, this is not the case for the time interval here considered. Its distribution was surely greater than the one mentioned below, because many species attributed to Pinna may belong to Atrina instead, but there are no specific data for the study interval.

  • Circumpacific domain: Middle Triassic: late Ladinian of Nevada (United States) (Waller & Stanley, 2005).

  • Tethys domain: Middle Triassic: Anisian of China (Stiller, 2001, personal communication, 2008).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Atrina living species are semi-infaunal bivalves that live endobyssate, attached by a strong byssus to rock fragments or other materials embedded in the sediment, with the commissure plane being almost vertical, similar to Pinna. Unlike Pinna, which lives with two-thirds of its shell into the sediment, Atrina lives almost completely buried (García-March, Márquez-Aliaga, & Carter, 2008). The same mode of life is assumed for Mesozoic specimens. The external shell spines were interpreted by S. M. Stanley (1970) as protection against breakage of the exposed portion of the shell, rather than a defensive device as in other bivalves.

  • Mineralogy.—Bimineralic (Carter, 1990a; Garcia-March, 2005). Outer shell layer: calcite (simple prismatic). Inner shell layer: aragonite (nacreous).

  • Figure 17.

    Paleogeographical distribution ot Posidoniidae (Bositra, Amonotis, Veldidenella, Caenodiotis, Steinmannia, Ellesmerella). 1, Early Triassic; 7, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f17_01.jpg

    Superfamily LIMOIDEA Rafinesque, 1815
    Family LIMIDAE Rafinesque, 1815
    Genus PALAEOLIMA Hind, 1903 in 1896—1905, p. 38

  • Type species.—Pecten simplex Phillips, 1836, p. 212.

  • Remarks.—Newell (1999, p. 4) rejected Palaeolima because the material of the type species was lost and topotypes were not available. On the other hand, Waller and Stanley (2005, p. 32) stated that “Dickins (1963, p. 91), however, had earlier addressed this problem and designated a neotype of Phillips's species, specifically the specimen figured by Hind (1903 in 1896–1905, p. 19, fig. 26) from Little Island, County Cork, Ireland.” According to these authors, Palaeolima remains valid.

  • Stratigraphic range.—Upper Devonian (?Fammenian)—Upper Triassic (Norian) (Lu, 1981; Waller & Stanley, 2005). Cox and others (1969) assigned it a Carboniferous—Late Triassic range. Following Waller and Stanley (2005), the range is extended back to the Upper Devonian. The youngest records are from the Upper Triassic of China (Lu, 1981; J. Chen, 1982a; Lu & Chen, 1986).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 19). Palaeolima had an almost cosmopolitan distribution during the Paleozoic, especially during the Carboniferous—Permian (until the Guadalupian) interval (Yancey, 1985; Gonzalez, 1992; Hoare, 1993; Nakazawa, 1999, 2002; Sterren, 2000, 2004; Cisterna & Sterren, 2003; Waller & Stanley, 2005). During the Triassic, it is found only from the Tethys and Circumpacific domains.

  • Tethys domain; late Permian; Kashmir (India) (Brookfield, Twitchett, & Goodings, 2003), China (Y. Zhang, 1981; M. Wang, 1993; L. Li, 1995); Early Triassic; China (Ling, 1988); Middle Triassic; Anisian of southern China (Komatsu, Akasaki, & others, 2004); Late Triassic; China (J. Chen, 1982a; Lu & Chen, 1986; Gou, 1993); Carnian of Italy (Corazzari & Lucchi-Garavello, 1980); Norian of China (Lu, 1981).

  • Circumpacific domain; Middle Triassic; Ladinian of Nevada (United States) (Waller & Stanley, 2005).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Living members of the family Limidae live epibyssate or reclined on the substrate or fixed by a slender byssus that may break, allowing occasional swimming (S. M. Stanley, 1970). From his observations of living species, S. M. Stanley (1970) concluded that good swimmers are often equivalve with symmetrical, equally sized auricles, and they have a large umbonal angle. In terms of external shell morphology, Palaeolima can be compared to the species Lima lima (Linnaeus, 1758), which lives epibyssate with a strong byssus. But the species assigned to Palaeolima lack a byssal notch. Other species, such as Lima scabra (Born, 1778) and Lima hians (Gmelin, 1791), are fairly symmetrical, live epibyssate with a weak byssus that can break, and swim occasionally (S. M. Stanley, 1970). Palaeolima has a rather symmetrical shell, and the auricles are of equal size, but the umbonal angle does not normally exceed 80° (from illustrations in the literature). We assume that Palaeolima lived epibyssate, as did P. scabra, although it is very unlikely that it could swim.

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 345). Outer shell layer: calcite (simple prismatic). Middle and inner shell layers; aragonite (cross-lamellar).

  • Genus AVICULOLIMA E. Philippi, 1900, p. 622

  • Type species.—Aviculolima jaekeli E. Philippi, 1900, p. 622.

  • Remarks.—Although Aviculolima is externally similar to Pteria, Cox and others (1969) included it in the Limidae with doubts. Having no further information, we follow these authors in their allocation.

  • Stratigraphic range.—Middle Triassic (Anisian) (Diener, 1923). The only information we have about Aviculolima was given by Diener (1923) and Cox and others (1969). In both papers, the authors limit themselves to transcribing data from the original paper in which the genus was proposed. The genus was reported from the Lower Muschelkalk of northern Germany (probably Anisian).

  • Paleogeographic distribution.—western Tethys (Fig. 19). According to available information, the genus appears to be endemic to northern Germany.

  • Tethys domain; Middle Triassic; Lower Muschelkalk of northern Germany (Diener, 1923).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Given its external resemblance to Pteria, probably it was an epifaunal and byssate bivalve, although the generic diagnosis does not mention byssal structures.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). There is no information about Aviculolima shell. Data provided for family Limidae. Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Genus BADIOTELLA Bittner, 1890, p. 94

  • Type species.—Badiotella schaurothiana Bittner, 1895, p. 201. (See notes in Bittner, 1895, p. 200, and Cox & others, 1969, p. 386, related to the nomenclatural status of this genus and its type species).

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Carnian) (Diener, 1923). Although Cox and others (1969) assigned it a Ladinian range, there is evidence that the genus was also present in the Upper Triassic (see Bittner, 1895; Broili, 1904; Diener, 1923). Sepkoski (2002) assigned it a Ladinian-Carnian range, following the compilation made by Hallam (1981). The youngest records are from Carnian beds (see paleogeographic distribution).

  • Paleogeographic distribution.—Tethys (Fig. 19).

  • Tethys domain; Middle Triassic; China (Lu & Chen, 1986); Ladinian of the Alps (Broili, 1904; Cox & others, 1969); Late Triassic; Carnian of the Alps (Bittner, 1895; Broili, 1904; Diener 1923), China (Gou, 1993).

  • Paleoautoecology.—B, E, S, Epi-Un, Sed; By-R. Like all members of this family, Badiotella was an epifaunal bivalve. Byssal structures are not reported in published literature, so it possibly lived slightly reclined or fixed by a weak byssus.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). There are no data about Badiotella mineralogy or shell microstructure. Information provided for family Limidae. Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (nonnacreous).

  • Genus LIMATULA Wood, 1839, p. 235

  • Type species.—Pecten subauriculata Montagu, 1808, p. 63.

  • Remarks.—Limatula and Limea Bronn, 1831, are genera with living representatives and conservative morphology. Even in Recent species, there is some confusion about which taxa should be referred to one genus or the other (Allen, 2004), and this distinction is much more complicated with fossil specimens.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Recent. Cox and others (1969) assigned it a Triassic—Holocene range. The oldest record is Ladinian (Tamura, 1973); we did not find any records from the Lower Triassic, or from the Lower Jurassic, although from Toarcian times onward, it was fairly common throughout the Jurassic (Hallam, 1976, 1977, 1981; Fürsich, 1982; Pugaczewska, 1986; Komatsu, Saito, & Fürsich, 1993; Liu, 1995; Sha and others, 1998; J. Yin & Grant-Mackie, 2005).

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 19).

  • Tethys domain; Middle Triassic: Ladinian of Malaysia (Tamura, 1973); Late Triassic: Rhaetian of Italy (Chiesa, 1949), Hungary (Vörös, 1981).

  • Circumpacific domain: Late Triassic: Norian of Japan (Tokuyama, 1959b; doubtful record also in Nakazawa, 1963).

  • Austral domain: Late Triassic: Carnian of New Zealand (Trechmann, 1918).

  • Paleoautoecology.—B, E, S, Epi, FaM; By-Sw. Some living species, such as Limatula strangei (G. B. Sowerby, 1872), live among rocks and corals, and they are able to swim (Beesley, Ross, & Wells, 1998). They have equivalve and slightly inequilateral shells and subequal auricles. The shell morphology remained practically unchanged from the Triassic to the present (Allen, 2004); we assume that Mesozoic species had similar modes of life. Limatula probably lived byssate most of the time and reclined on the substrate, with the anterior part down (Fürsich, 1982).

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 345). Outer shell layer: calci te (prismatic). Inner shell layer: aragonite (?).

  • Genus LIMEA Bronn, 1831, p. 115

  • Type species.—Ostrea strigilata Brocchi, 1814, p. 571.

  • Remarks.—The only subgenus considered by Cox and others (1969) in our study interval is Limea (Eolimea) Cox in Cox and others, 1969, p. 389, with a Middle Triassic range. From the Middle Triassic to the Miocene, when Limea (Limea) appears, there is a long time interval without records of this genus. This was noticed by Dhondt (1989), who also noted that Pseudolimea Arkell in Douglas & Arkell, 1932, which ranges from Triassic to Cretaceous, was distinguished from Limea mainly by the shape of the ribs. Moreover, other subgenera of Limea, such as Isolimea or Eolimea, are differentiated by their strong ornamentation. Dhondt noted that Pseudolimea was very similar to Limea and it could fill this time gap, and she included it as a subgenus of Limea. This arrangement is followed here.

  • Stratigraphic range.—Middle Triassic (Anisian)—Holocene (Cox & others, 1969). The stratigraphic range of Limea recognized here is the same as in Cox and others (1969). The oldest record is from Anisian times (Kaim, 1997).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 19).

  • Tethys domain: Middle Triassic: Poland (Kaim, 1997); Anisian western Caucasus (Russia) (Ruban, 2006a); Ladinian of Spain (Márquez-Aliaga, 1983; Pérez-López, 1991; Pérez-López & others, 1991; López-Gómez & others, 1994; Márquez-Aliaga & Martínez, 1996; Márquez-Aliaga, García-Forner, & Plasencia, 2002), Italy (Rossi Ronchetti, 1959); Late Triassic: Norian of southern China (J. Chen & Yang, 1983); Early Jurassic: Hettangian of northern Alps (Austria) (Golebiowski, 1990); Hettangian—Sinemurian of England (Liu, 1995), Spain (Calzada, 1982); Sinemurian of France, Portugal, and Morocco (Liu, 1995), Turkey (M. A. Conti & Monari, 1991).

  • Circumpacific domain: Late Triassic: Carnian of Japan (Nakazawa, 1952; Hayami, 1975); Norian of Oregon (United States) (Newton in Newton & others, 1987), Nevada (United States) (Laws, 1982); Norian of Chile (Hayami, Maeda, & Ruiz-Fuller, 1977); Rhaetian of Chile (Chong & Hillebrandt, 1985); Early Jurassic: Hettangian—Sinemurian of western Canada (Aberhan, 1998a; Aberhan, Hrudka, & Poulton, 1998), Chile (Aberhan, 1994a).

  • Austral domain: Late Triassic: Carnian of New Zealand (GrantMackie, 1960); Rhaetian of New Zealand (MacFarlan, 1998) and Argentina (Damborenea & Man ceñido, 2012); Early Jurassic: Hettangian—Sinemurian of Neuquén Basin (Argentina) (Damborenea, 1996a; Damborenea & Manceñido, 2005b), New Zealand (MacFarlan, 1998).

  • Boreal domain: Early Jurassic: Hettangian—Sinemurian of ?Greenland (Liu, 1995).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Limea is a long-ranging genus that exhibits a conservative morphology throughout its history (Allen, 2004). The Recent species of this genus live mainly in deep water, and it was proposed that the extinct species also lived mostly in this type of environment (Dhondt, 1989). Limea species probably lived as epibyssate and reclined on one of the valves (Fürsich, 1982), similar to living species.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). There are no data about Limea shell. Data provided for family Limidae. Outer shell layer: calci te (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Genus MYSIDIOPTERA Salomon, 1895, p. 117

  • Type species.—Mysidioptera ornata Salomon, 1895, p. 117.

  • Remarks.—Two subgenera are considered in the study interval, M. (Mysidioptera) and M. (Pseudacesta) Waagen, 1907, p. 113.

  • Stratigraphic range.—Lower Triassic (Olenekian)—Upper Triassic (Rhaetian). Cox and others (1969) assigned it a Lower Triassic—Upper Triassic range, and this is maintained here. Mysidioptera was not abundant in the Triassic, but it had a climax during Ladinian and Carnian; and although it was scarce during the Rhaetian, it lived to the end of the stage, when it became extinct.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 19).

  • Tethys domain: Middle Triassic: Anisian of China (Wen & others, 1976; Lu & Chen, 1986; Sha, Chen, & Qi, 1990; Komatsu, Chen, & others, 2004; Komatsu, Akasaki, & others, 2004), Malaysia (Tamura & others, 1975), Swiss Dolomites (Zorn, 1971), Italian Dolomites (Posenato, 2008b), Israel (Lerman, 1960), northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of Alps (Austria) (Salomon, 1895), north of Vietnam and Thailand (Vu Khuc & Huyen, 1998), Malaysia (Tamura, 1973), Lombardy (Italy) (Rossi Ronchetti, 1959), northern Vietnam (Komatsu, Huyen, & Huu, 2010); Late Triassic; China (Gou, 1993); Carnian of southern Alps (Bittner, 1895, 1900; Salomon, 1895; Broili, 1904; Allasinaz, 1966; Fürsich & Wendt, 1977; Posenato, 2008a, 2008b), Carpathians (Slovakia) (Bujnovsky, Kochanová, & Pevny, 1975; Kochanová, Mello, & Siblík, 1975), Jordan (Cox, 1924); Rhaetian of Tibet (China) (Hallam & others, 2000), East of the Alps (Austria) (Tomašových, 2006a, 2006b).

  • Circumpacific domain; Early Triassic; Olenekian of Japan (Nakazawa, 1961; Hayami, 1975); Late Triassic; Japan (Hayami, 1975), Norian of Oregon (Newton in Newton & others, 1987), Norian of Sonora (Mexico) (Damborenea in Damborenea & González-León, 1997).

  • Austral domain; Late Triassic; Carnian of New Zealand (Waterhouse, 1960).

  • Boreal domain; Late Triassic; Carnian of Arctic area of British Columbia (Canada) (Tozer, 1962, 1970).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The external shell morphology of different species attributed to Mysidioptera indicates an epibyssate habit, since most show a byssal notch. It could live on both hard and soft substrates (Newton in Newton & others, 1987). They were reported from a variety of facies, as they are thought to have colonized different environments (Damborenea in Damborenea & González-León, 1997).

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). There are no data about Mysidioptera shell mineralogy. Data provided for family Limidae. Outer shell layer: calci te (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Genus PLAGIOSTOMA J. Sowerby, 1814, p. 175

  • Type species.—Plagiostoma gigantea J. Sowerby, 1814, p. 176.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Cretaceous (Maastrichtian) (Abdel-Gawad, 1986; Komatsu, Chen, & others, 2004). Cox and others (1969) assigned it a Middle Triassic—Cre—taceous range. However, Sepkoski (2002) considered it to be from the Lower Triassic (Induan), indicating that data were taken from Abdel-Gawad (1986), but this author only mentioned Plagiostoma from the Cretaceous. This datum is wrong, since Plagiostoma was not present before the Middle Triassic (see Paleogeographic distribution, below), and it may have derived from Lower Triassic Mysidioptera (Bittner, 1895; Waller & Stanley, 2005). Dagys and Kurushin (1985) reported Plagiostoma aurita (Popov) and Plagiostoma popovi Kurushin in Dagys & Kurushin, 1985, from the Lower Triassic, but the figured specimens have little in common with the diagnosis of the genus Plagiostoma.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 19).

  • Tethys domain; Middle Triassic; Hungary (Szente, 1997), Poland (Kaim, 1997); Anisian of Germany (Hautmann, 2006a), southern China (Sha, Chen, & Qi, 1990; Komatsu, Chen, & others, 2004), Switzerland (Zorn, 1971); Ladinian of Sardinia (Italy) (Posenato, 2002; Posenato & others, 2002), Malaysia (Tamura, 1973; Tamura & others, 1975); Late Triassic: China (J. Chen, 1982a; Gou, 1993), Oman (R. Hudson & Jefferies, 1961); Carnian of Malaysia (Tamura & others, 1975), Lombardy (Italy) (Allasinaz, 1966); Norian of Himalaya (Tibet, China) (J. Yin, Enay, & Wan, 1999), southern China (Wen & others, 1976; Sha, Chen, & Qi, 1990), northwestern China (Lu, 1981); Norian—Rhaetian of Iran and the Alps (Hautmann, 2001b); Rhaetian of eastern Alps (Austria) (Tomašových, 2006a, 2006b), Tibet (China) (Hautmann & others, 2005; J. Yin & McRoberts, 2006), Hungary (Vörös, 1981), Lombardy (Italy) (Allasinaz, 1962); Early Jurassic; Hettangian of southern England (Ivimey-Cook & others, 1999), Tibet (China) (Hautmann & others, 2005; J. Yin & McRoberts, 2006), Italy (Gaetani, 1970); Hettangian—Sinemurian of England and France (Liu, 1995), Lombardy (Italy) (Allasinaz, 1962); Sinemurian of Caucasus (southwestern Russia) (Ruban, 2006b), Portugal and Morocco (Liu, 1995).

  • Circumpacific domain; Middle Triassic; Ladinian of Nevada (United States) (Waller & Stanley, 2005); Late Triassic; Japan (Kobayashi & Ichikawa, 1949a; Tokuyama, 1959a); Carnian of Japan (Hayami, 1975); Norian of Oregon (United States) (Newton in Newton & others, 1987; but see Waller & Stanley, 2005); Early Jurassic; ?Mexico (Damborenea in Damborenea & González-León, 1997); Hettangian—Sinemurian of western Canada (Aberhan, 1998a), Mexico and Texas (Liu, 1995), northern Chile (Aberhan, 1994a); Sinemurian of Japan (Hayami, 1975; Hayami in Sato & Westermann, 1991).

  • Austral domain; Early Jurassic; Sinemurian of Neuquén Basin (Argentina) (Damborenea, 1996a; Damborenea & Manceñido, 2005b).

  • Boreal domain; Late Triassic; Carnian of Primorie (Kiparisova, 1972).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Like most limids, Plagiostoma was probably an epibyssate bivalve. Although no description pointing to a byssal notch was found, we assume that the byssus would have emerged below the anterior auricle. We cannot rule out that it could eventually swim, but this is unlikely due to the shell thickness (Seilacher, 1984); a reclining habit on its broad anterior base is more likely.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 215; Carter, 1990b, p. 345). Outer shell layer: calci te (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Genus SERANIA Krumbeck, 1923a, p. 218

  • Type species.—Serania seranensis Krumbeck, 1923a, p. 218.

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (Hautmann, 2001b). According to Kutassy (1931), Serania was proposed by Krumbeck (1923a) on the basis of material from Norian beds of Indonesia and Persia. Cox and others (1969) assigned it a Norian age, as did also Sepkoski (2002), based on Hallaras (1981) data. It was subsequently reported also from Rhaetian beds (Hautmann, 2001b).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 19). Serania was a monospecific genus endemic for the eastern Tethys.

  • Tethys domain; Late Triassic; Norian of Indonesia and Persia (Kutassy, 1931); Norian—Rhaetian of Iran (Hautmann, 2001b).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Like most members of family Limidae, Serania was probably an epibyssate bivalve, similar to Plagiostoma (Hautmann, 2001b). Serania seranensis shows a deep byssal notch (see Cox & others, 1969, p. 392), which implied a strong byssus.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). There are no data about the shell of Serania. Data provided for family Limidae. Outer shell layer: calci te (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Figure 18.

    Paleogeograpbical distribution of Pinnidae (Pinna, Atrina). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f18_01.jpg

    Genus TIROLIDIA Bittner, 1895, p. 202

  • Type species.—Lima (Tirolidia) haueriana Bittner, 1895, p. 202.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Carnian) (Diener, 1923). Cox and others (1969) assigned a Middle Triassic—Upper Triassic range. Bittner (1895) proposed Tirolidia from Ladinian and Carnian beds of the southern Alps. Diener (1923) and Kutassy (1931) provided the same data. Little else could be found, except that Hallam (1981) assigned it a Ladinian—Carnian range in western Tethys, and thus this genus seems to be endemic to the southern Alps.

  • Paleogeographic distribution.—western Tethys (Fig. 19).

  • Tethys domain: Middle Triassic: Ladinian of Southern Alps (Bittner, 1895); Late Triassic: Carnian of Southern Alps (Bittner, 1895).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Tirolidia is slightly inequilateral and has unequal auricles, so it is not a good candidate to be a swimmer. We assign it an epibyssate mode of life, similar to other members of this family.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). No specific data about Tirolidia mineralogy and shell microstructure are known. Data provided for family Limidae. Outer shell layer: calci te (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Genus ANTIQUILIMA Cox, 1943, p. 179

  • Type species.—Lima antiquata J. Sowerby, 1818, p. 25.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Lower Cretaceous (Aptian) (Hayami, 1965; Waller & Stanley, 2005). Cox and others (1969) considered it to be a Jurassic genus (Liassic—Baj ocian), but, since then, new records have expanded its range. The oldest record of Antiquilima is from Ladinian beds of Nevada (Waller & Stanley, 2005) and the youngest from Lower Cretaceous beds (Aptian) (Hayami, 1965).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 19). According to Damborenea (2000), Antiquilima probably originated in the Eastern Pacific and subsequently it spread to the Tethys, which agrees with the data found about the genus.

  • Tethys domain: Late Triassic: Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of the Alps (Austria) (Tomašových, 2006a, 2006b), Tibet (China) (J. Yin & McRoberts, 2006), western Carpathians (Slovakia) (Tomášových, 2004); Early Jurassic: Hettangian—Sinemurian of England (Liu, 1995); Sinemurian of France (Vörös, 1971; Liu, 1995), Apennines (Italy) (Monari, 1994).

  • Circumpacific domain: Middle Triassic: Ladinian of Nevada (United States) (Waller & Stanley, 2005); Late Triassic: Norian of northern Chile (Hayami, Maeda, & Ruiz-Fuller, 1977), Oregon (United States) (Newton, 1986; Newton in Newton & others, 1987); Early Jurassic: Hettangian—Sinemurian of northern Chile (Aberhan, 1994a); Sinemurian of Canada (Aberhan, 1998a), Japan (Hayami, 1975).

  • Austral domain: Early Jurassic: Sinemurian of Argentina (Damborenea, 1996a; Damborenea & Manceñido, 2005b; Damborenea & Lanes, 2007).

  • Boreal domain: Late Triassic: Carnian of Primorie (Kiparisova, 1972); Norian of northeastern of Asia (Kurushin, 1990; Polubotko & Repin, 1990); Norian—Rhaetian of eastern Siberia (Kiparisova, Bychkov, & Polubotko, 1966), northeastern Russia (Milova, 1976); Early Jurassic: Hettangian of northeastern Asia (Kurushin, 1990; Polubotko & Repin, 1990), northeastern Russia (Milova, 1976).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. In most species, a byssal notch is present (e.g., specimens described in Hayami, Maeda, & Ruiz-Fuller, 1977; Newton in Newton & others, 1987; Hautmann, 2001b), and most likely it was an epibyssate bivalve as in the rest of the limids. According to Newton (in Newton & others, 1987), Antiquilima could sever the byssus and swim for short distances, as do some modern species of the family Limidae. However, due to its external morphology, it was probably not a good swimmer.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215; Waller & Stanley, 2005). Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Genus CTENOSTREON Eichwald, 1862, p. 374

  • Type species.—Ostracites pectiniformis von Schlotheim, 1820, p. 231.

  • Stratigraphic range.—Upper Triassic (upper Rhaetian)—Lower Cretaceous (?Valanginian). Cox and others (1969) assigned it a Jurassic (Liassic)—Lower Cretaceous (Neocomian) range. Sepkoski (2002) considered that it originated in the lower Hettangian following Hallam (1977, 1987). The origin of this genus was regarded as Hettangian for a long time (Hallam, 1977, 1987, 1990), but recently J. Yin, H. Yao, and Sha (2004) and J. Yin and McRoberts (2006) found Ctenostreon in layers transitional between the Rhaetian and Hettangian. These Himalayan records were dated as Rhaetian, because they were associated with the ammonoid Choristoceras (J. Yin, H. Yao, & Sha, 2004). We ignore to what part of the Neocomian Cox and others (1969) referred for the last record. The youngest record of the genus dates from Valanginian times (Császár & Turnšek, 1996), but specimens were neither figured nor described, so we tentatively consider this as the last appearance.

  • Paleogeographic distribution.—Tethys, Austral, and Circumpacific (Fig. 19).

  • Tethys domain: Late Triassic: Rhaetian of southern China (J. Yin, H. Yao, & Sha, 2004; J. Yin & McRoberts, 2006); Early Jurassic: Hettangian of Tibet (China) (J. Yin & McRoberts, 2006; J. Yin & others, 2007).

  • Austral domain: Early Jurassic: Hettangian—Sinemurian of the Neuquén Basin (Argentina) (Damborenea, 1996a; Damborenea & Manceñido, 2005b).

  • Circumpacific domain: Early Jurassic: Sinemurian of Japan (Hayami, 1975), Chile (Aberhan, 1994a).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Ctenostreon is regarded as an epibyssate bivalve, although the byssal notch is not always evident and sometimes it is even absent. Its shell is thick compared with other members of this family; we assume that it would not need a very strong byssus. Seilacher (1984) suggested that it is one of those limids for which a swimming mode of life is excluded, due to its thick shell and presence of spines; it was probably a pleurothetic reclined bivalve.

  • Mineralogy.—Bimineralic (Cox & others, 1969; Carter, 1990a, p. 215). No specific data about Ctenostreon mineralogy and shell microstructure is known. Information provided for family Limidae. Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (non-nacreous).

  • Figure 19.

    Paleogeographical distribution of Limidae (Palaeolima, Aviculolima, Badiotella, Limatula, Limea, Mysidioptera, Plagiostoma, Serania, Tirolidia, Antiquilima, Ctenostreon). 1, late Permian—Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f19_01.jpg

    Superfamily OSTREOIDEA Wilkes, 1810
    Family GRYPHAEIDAE Vialov, 1936
    Genus GRYPHAEA Lamarck, 1801, p. 398

  • Type species.Gryphaea arcuata Lamarck, 1801, p. 398.

  • Remarks.—Newell and Boyd (1970, 1989, 1995) discussed the external morphological similarity between Pseudomonotis and Gryphaea (see fig. 47 in Newell & Boyd, 1995). Frequently, these genera can only be distinguished by the shell microstructure and which valve is attached to the substrate (right and left respectively) (Newell & Boyd, 1995). Many of the Pseudomonotis records from Triassic and Jurassic could actually belong to Gryphaea, since Pseudomonotis is now regarded as a strictly Paleozoic genus, and it is not an ostreoid.

  • Stratigraphic range.—Upper Triassic (Carnian)—Upper Cretaceous (Campanian) (McRoberts, 1992; Newell & Boyd, 1989). Stenzel (1971) considered that Gryphaea was present in the Upper Triassic of the Boreal domain and had a worldwide distribution for most of the Jurassic (Hettangian—Oxfordian). New records changed the observed stratigraphic range of this genus; Gryphaea was reported from Upper Triassic beds, from the Carnian (McRoberts, 1992) in the Paleopacific eastern margin, in addition to the Boreal regions. It had not been found anywhere in upper Norian and Rhaetian beds, so McRoberts (1992) interpreted it as a Lazarus taxon that reappeared in the Hettangian stage, but Rubilar (1998) reported Gryphaea from the Norian—Rhaetian of Chile.

  • The youngest record is from the Upper Cretaceous (Newell & Boyd, 1989). Although there are some papers that mentioned Gryphaea up until the Pleistocene, they are not taken into account as they are bio-stratigraphic studies and they do not describe or figure the listed material.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 20).

  • Tethys domain; Early Jurassic: Tibet (China) (Gou, 2003); Hettangian of Italy (Gaetani, 1970); Hettangian—Sinemurian of France (Liu, 1995; Nori & Lathuilière, 2003), England, Spain, Portugal, and Morocco (Liu, 1995).

  • Circumpacific domain; Late Triassic; Carnian—Norian of Canada, Oregon, and Nevada (United States) (McRoberts, 1992), northern and southern Alaska (McRoberts, 1992; McRoberts & Blodgett, 2000); Norian of Chile (Hayami, Maeda, & Ruiz-Fuller, 1977); Norian—Rhaetian of Chile (Rubilar, 1998); Early Jurassic: Hettangian of Chile (Aberhan, 1994a); Sinemurian of Chile (Steinmann, 1929; Chong & Hillebrandt, 1985; Hillebrandt, 1990; Aberhan, 1994a; Malchus & Aberhan, 1998; Rubilar, 1998), Canada (Poulton, 1991).

  • Austral domain; Early Jurassic; Sinemurian of Argentina (Damborenea & Manceñido, 2005b; Damborenea & Lanés, 2007).

  • Boreal domain; Late Triassic; Arctic area of Siberia (Kiparisova, 1954), northeastern Russia (Milova, 1976); Carnian of Arctic Island (Canada) (Tozer, 1970); Carnian—Norian of Primorie (Kiparisova, 1972); Early Jurassic; Hettangian of northeastern Russia (Milova, 1988).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Some species of Gryphaea lived cemented to the substrate during the juvenile stages, but they often changed to a reclined life habit in the adult stage (Fürsich & others, 2001). Seilacher (1984) interpreted certain Gryphaea species as being cup-shaped recliners, living on soft substrates: they probably rested on their left valve, which is strongly convex and thick, unlike the flat and smooth right valve. The left valve was used to anchor the shell to soft sediments. Gryphaea would thus live epifaunally or partially buried. The specimens are usually found in fine-grained sediments (clay, marl) that are characteristic of low-energy marine environments (Lewy, 1976). The shell morphology of Gryphaea, as in other ostreids, is strongly influenced by the environment. Nori and Lathuilière (2003) proved that several factors (temperature, oxygen level, and humidity) were responsible for the different morphologies.

  • Mineralogy.—?Bimineralic (Carter, 1990a, p. 232). Although the shell microstructure of Triassic specimens is not known, Jurassic specimens have a prismatic outer shell layer and a foliated inner shell layer, both being calcitic (Carter, 1990a). However, McRoberts and Carter (1994) found that middle and inner layers of G. nevadensis were originally of nacreous microstructure (aragonite).

  • Family OSTREIDAE Wilkes, 1810
    Genus UMBROSTREA Hautmann, 2001a, p. 359

  • Type species.—Umbrostrea emamii Hautmann, 2001a, p. 361.

  • Remarks.—Hautmann (2001a) proposed Umbrostrea to include some specimens from the Upper Triassic of Iran that attached by the left valve (consensual basis for defining the true oysters), built reefs, and possessed an inner foliated shell microstructure and aragonitic inner shell layer (data considered as preliminary by the author). He proposed two new species, Umbrostrea emamii and Umbrostrea iranica, and tentatively considered Umbrostrea? aff. parasitica (Krumbeck, 1913) within the genus. Subsequently, Márquez-Aliaga and others (2005) examined a sample of hundreds of specimens attributed to Enantiostreon difforme (Goldfuss, 1833 in 1833–1841) [=Ostracites cristadifformis Schlotheim, 1820] and Enantiostreon spondyloides (Schlotheim, 1820) from the Lower and Upper Muschelkalk (Middle Triassic, Anisian—Ladinian) of the Germanic Basin, from levels equivalent to those from where the Enantiostreon species were described, attributed by these authors to real oysters. The authors accepted that the first record of ostreids from those levels was by Seilacher (1954), who classified some specimens attached by their left valve to Plagiostoma shells as Alectryonia (=Lopha), but with Enantiostreon morphology. Seilacher (1954) relied on the kind of so-called twisting of the valves and on the antimarginal pattern of the shell folds. This last criterion was developed by Checa and Jiménez-Jiménez (2003b) for cemented bivalves, and it is characteristic of ostreids. In the same paper, Márquez-Aliaga and others (2005) studied the Hispanic Muschelkalk (Ladinian) specimens attributed to E. difformis by Márquez-Aliaga (1985), on which microstructural studies were performed (De Renzi & Márquez-Aliaga, 1980; Márquez-Aliaga & Martínez, 1990b; Márquez-Aliaga & Márquez, 2000). In these studies, the authors verified the presence of foliated and calcitic outer shell layer and an inner shell layer replaced by sparite of possible aragonitic origin; this type of microstructure is characteristic of ostreids. However, the absence of internal features in all the studied specimens did not solve the controversial problem of the origin of the oysters. Thus, several replies to this proposal were generated, including other evolutionary aspects (see discussion in Márquez-Aliaga & others, 2005; Hautmann, 2006b; Checa & others, 2006; and Malchus, 2008). Other authors, like Ivimey-Cook and others (1999) and J. Yin and McRoberts (2006), preferred to include the species Enantiostreon difforme within Terquemia Cox, 1964. Here we provisionally accept the criteria of Márquez-Aliaga and others (2005).

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Rhaetian) (Hautmann, 2001a; Márquez-Aliaga & others, 2005). Hautmann (2001a, 2001b) assigned it a Norian—Rhaetian range. Accepting the species assigned by Márquez-Aliaga and others (2005) into Umbrostrea, the range extends from the Middle Triassic, with the origin of U. cristadifformis and U. spondyloides being in Anisian times.

  • Paleogeographic distribution.—Tethys (Fig. 21).

  • Tethys domain: Middle Triassic: Anisian of Poland (Kaim, 1997), Bulgaria (Budurov & others, 1993), Hungary (Szente, 1997); Ladinian of Sardinia (Márquez-Aliaga & others, 2000; Posenato, 2002), Spain (Márquez-Aliaga, 1985; Márquez-Aliaga & Martínez, 1996); Late Triassic: Norian of Indonesia (Diener, 1923); Norian—Rhaetian of Iran (Hautmann, 2001a, 2001b; Fürsich & Hautmann, 2005), Rhaetian of England (Ivimey-Cook & others, 1999), ?Rhaetian of Tibet (China) (J. Yin & McRoberts, 2006).

  • Paleoautoecology.—B, E, S, C, Sed; C. Although Hautmann (2001a, 2001b) considered that Umbrostrea lived cemented to the substrate by the left valve, the species U. cristadifformis and U. spondyloides could attach by either valve (Márquez-Aliaga & others, 2005). It lived forming small reefs in fully marine environments and was associated with corals, brachiopods, and other bivalves (Hautmann, 2001a).

  • Mineralogy.—Bimineralic (De Renzi & Márquez-Aliaga, 1980; Carter, Barrera, & Tevesz, 1998; Hautmann, 2001a). In the diagnosis of Umbrostrea, Hautmann (2001a) indicated that the species attributed to this genus are characterized by a regular simple prismatic outer shell layer of calcite, a middle shell layer of foliated calcite, and an aragonitic inner shell layer of unknown microstructure. Umbrostrea cristadifformis had a foliated calcitic outer shell layer and an aragonitic inner shell layer (De Renzi & Márquez-Aliaga, 1980). According to Carter, Barrera, and Tevesz (1998), U. spondyloides (upper Muschelkalk, Ladinian, southwestern Germany) had an aragonitic inner shell layer and calcitic middle and upper shell layers, the last with regular to homogeneous and irregular prismatic microstructures. Outer shell layer: calcite (simple prismatic—foliated). Middle shell layer: calcite (ifoliated). Inner shell layer: aragonite (?nacreous).

  • Figure 20.

    Paleogeograpbical distribution of Gryphaeidae (Gryphaea). Late Triassic—Early Jurassic.

    f20_01.jpg

    Genus ACTINOSTREON Bayle, 1878, expl. pl. 132

  • Type species.—Ostrea solitaria J. de C. Sowerby, 1824, p. 105.

  • Remarks.—Palaeolopha Malchus, 1990, is regarded a junior synonym of Actinostreon (see discussion under Palaeolopha, Genera not Included, p. 166).

  • Stenzel (1971) considered Actinostreon as a subgenus of Lopha, and this was followed by most authors. However, Malchus (1990) included Actinostreon, together with his new genus Palaeolopha, in his new family Palaeolophidae, and he regarded Actinostreon as an independent genus different from Lopha. Checa and Jiménez-Jiménez (2003b) included the species Enantiostreon difforme (Goldfuss, 1833 in 1833–1841) [=Ostracites cristadifformis Schlotheim, 1823 in 1822–1823] in Actinostreon, since Malchus (1990) included this species in Palaeolopha, and they followed the synonymy proposed by Hautmann (2001a, p. 359), i.e. Actinostreon =Palaeolopha Malchus, 1990). Subsequently, Márquez-Aliaga and others (2005) included the species cristadifformis in Umbrostrea Hautmann, 2001a.

  • Stratigraphic range.—Upper Triassic (Rhaetian)—Upper Cretaceous (Maastrichtian) (Chiplonkar & Badve, 1977; Hautmann, 2001a). Stenzel (1971) assigned it a Jurassic—Cretaceous range; these data were incorporated by Sepkoski (2002), who added Maastrichtian as the last appearance, but he did not indicate the original source. The oldest records are from Rhaetian (Ivimey-Cook & others, 1999; Hautmann, 2001a). Actinostreon was very well represented throughout the Jurassic, and there are very few records from the Cretaceous. The youngest record is the species Lopha (Actinostreon) diluvian (Linnaeus) from Maastrichtian beds (Chiplonkar & Badve, 1977), quoted also by Ayyasami (2006) from the Turonian, both in southern India, although the latter is a biostratigraphic paper. However, this species is frequently assigned to Lopha, although according to Malchus (1990), Lopha had a Tertiary origin.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 21).

  • Tethys domain; Late Triassic; Rhaetian of England (Penarth Group) (Ivimey-Cook & others, 1999), Austria (Hautmann, 2001a).

  • Circumpacific domain; Late Triassic; Norian of Mexico (Damborenea in Damborenea & González-León, 1997); Early Jurassic; Hettangian—Sinemurian of Mexico and Texas (United States) (Liu, 1995), Andes (Chile and Argentina) (Damborenea, 1996a, 2000); Sinemurian of Chile (Aberhan, 1994a; Sha, Smith, & Fürsich, 2002), Japan (Toyora Group) (Hayami, 1975).

  • Austral domain; Early Jurassic; Hettangian—Toarcian of the Andes (Chile and Argentina) (Damborenea, 1996a, 2000).

  • Paleoautoecology.—B, E, S, C, Sed; C. Actinostreon was a cemented bivalve that attached itself to the substrate by the left valve. Usually it formed clusters in high-energy marine environments (Sha, Smith, & Fürsich, 2002). It could attach to inorganic substrates and also to the shells of other organisms. Most often it attached by cementation to individuals of the previous generation, but it was also found on other bivalves (e.g., Modiolus in Ivimey-Cook & others, 1999) or solitary (Machalski, 1998). According to Sha (2002), ostreids have planktotrophic larvae that are responsible for their wide dispersion.

  • Mineralogy.—Calcitic (Carter, 1990a; Hautmann, 2001a). According to Carter (1990a), Lopha haidingeriana (Emmrich, 1853) had predominantly foliated middle and inner shell layers, but a thin prismatic outer shell layer may also be present. Hautmann (2001a) found no trace of an aragonitic inner shell layer in one of his Actinostreon haidingerianum (Emmrich, 1853) specimens, and in a tangential section, he observed thin layers of foliated structure. The aragonite is limited to the miostracum and ligostracum (Hautmann, 2001a). The shells show a typical structure with biconvex chambers (Malchus, 1998). Outer shell layer: calcite (?prismatic). Middle and inner shell layers; calcite (regular foliated).

  • Figure 21.

    Paleogeographical distribution or Ostreidae (Umbrostrea, Actinostreon, Liostrea). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f21_01.jpg

    Genus LIOSTREA Douvillé, 1904, p. 273

  • Type species.—Ostrea sublamellosa Dunker, 1846, p. 41.

  • Stratigraphic range.—Upper Triassic (Carnian)—Upper Cretaceous (Cenomanian) (Hayami, 1975; Carter, 1990a). Stenzel (1971) reported Liostrea as being present in the Norian of Siberia and from the Rhaetian to the Jurassic of Europe. Subsequently, the genus was reported from Carnian beds of Japan (Hayami, 1975). The oldest record is from the Ladinian (Waller in Waller & Stanley, 2005), but, in these specimens, some diagnostic characters are not seen, and thus a definite identification is not possible. This record is regarded as dubious Liostrea until more material is found in the area. If confirmed, the origin of Liostrea goes back to the Middle Triassic. According to Carter (1990a), the youngest record is Liostrea oxiana Romer from the Cretaceous (Cenomanian) (Seeling & Bengtson, 1999).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 21).

  • Tethys domain; Late Triassic: Carnian of China (J. Chen, 1982a), ?Italy (Gaetani, 1970); Rhaetian of Tibet (China) (?Hautmann & others, 2005; J. Yin & McRoberts, 2006), England (Ivimey-Cook & others, 1999), Italy (Gaetani, 1970); Early Jurassic; Hettangian ofTibet (China) (?Hautmann & others, 2005; J. Yin & McRoberts, 2006), England (Liu, 1995; Ivimey-Cook & others, 1999), Italy (Gaetani, 1970); Sinemurian of England and Portugal (Liu, 1995).

  • Circumpacific domain; Late Triassic; Carnian of ?Peru (Cox, 1949); Norian of Oregon (United States) (Newton, 1986; Newton in Newton & others, 1987); Norian—Rhaetian of Chile (Rubilar, 1998); Early Jurassic; Sinemurian of Japan (Hayami, 1975), Chile (Rubilar, 1998).

  • Austral domain; Late Triassic; Rhaetian of Argentina (Riccardi & others, 2004; Damborenea & Manceñido, 2012).

  • Boreal domain; Late Triassic; Norian of Siberia (Stenzel, 1971); Early Jurassic; Hettangian—Sinemurian of Greenland (Liu, 1995).

  • Paleoautoecology.—B-Ps, E, S, C, Sed-FaM; C. Liostrea cemented to the substrate by the left valve, like the other ostreids. Unlike Gryphaea, it has a large cementation area. Liostrea cemented itself to hard substrates, bivalve shells, or other organisms (Newton in Newton & others, 1987). It was usually found forming reefs during the Jurassic (Fürsich, Palmer, & Goodyear, 1994). However, the species Liostrea erina (d'Orbigny) was found cemented to ammonoids (Leioceras) in the Middle Jurassic Opalinum Clay (Switzerland), so it is supposed to have been pseudoplanktonic (Etter, 1996). This author found evidence indicating that the cementation was achieved when the ammonoids were still alive (see fig. 4 in Etter, 1996). Other species, such as L. plastica (Trautschold) from the Upper Jurassic of Greenland, were also found cemented to ammonoids, but it was not possible to determine whether the cementation was pre- or postmortem for the ammonites (Fürsich, 1982).

  • Mineralogy.—?Calcitic (Carter, Barrera, & Tevesz, 1998). There are no conclusive studies on Liostrea mineralogy or shell microstructure. According to Carter, Barrera, and Tevesz (1998), the mineralogy of the different shell layers of members of family Ostreidae is calcitic.

  • Superfamily DIMYOIDEA Fischer, 1886 in 1880–1887
    Family DIMYIDAE Fischer, 1886 in 1880–1887
    Genus ATRETA Etallon, 1862, p. 191

  • Type species.Ostrea blandina d'Orbigny, 1850, p. 375 (designated by Cox, 1964, p. 45).

  • Remarks.Dimyodon Munier-Chalmas in Fischer, 1886 in 1880—1887, p. 937, is considered to be a junior synonym of Atreta (see discussion for Dimyodon, Genera not Included, p. 160). Although for a long time it was regarded as a plicatulid, both Fürsich and Werner (1988) and Hodges (1991), analyzing specimens of Atreta unguis (Loriol ex Merian, 1900) and Atreta intusstriata (Emmrich, 1853), respectively, demonstrated the presence of dimyarian structures typical of family Dimyidae.

  • Stratigraphic range.—Upper Triassic (Carnian)—Upper Cretaceous (Maastrichtian) (Bittner, 1895; Abdel-Gawad, 1986). Cox and others (1969) assigned it an Upper Triassic (Carnian)—Upper Cretaceous (Campanian) range. Sepkoski (2002) referred its origin to the Rhaetian, based on data provided by Skelton and Benton (1993). The oldest records of Atreta are from Carnian beds, with the species A. richthofeni (Bittner, 1895) and A. subrichthofeni (Krumbeck, 1924). H. Yin (1985) reported Dimyodon from Anisian and Ladinian beds. J. Chen, Stiller, and Komatsu (2006) believed that Anisian specimens of Dimyodon (D. qingyanensis Yin in Gan & Yin, 1978) were actually juvenile stages of Protostrea sinensis Hsu in Hsu & Chen, 1943 (type of Protostrea Chen, 1976). Atreta nilssoni (von Hagenow, 1842) is the latest species of the genus, reported from the Maastrichtian (Abdel-Gawad, 1986).

  • Paleogeographic distribution.—Tethys (Fig. 22). Over the study interval, this genus was only known from the Tethys domain, but in the upper Pliensbachian, it is recorded from Argentina (Damborenea, 2002a). Atreta showed dispersal patterns from the western Tethys to Eastern Circumpacific domain across the Hispanic corridor during the Early Jurassic (Damborenea, 2000).

  • Tethys domain; Late Triassic; Carnian of southern Alps (Bittner, 1895; F¨rsich & Wendt, 1977), Timor (Krumberck, 1924); Norian of Oman (Hautmann, 2001a); Norian—Rhaetian of Austria (Tanner, Lucas, & Chapman, 2004), Iran (Hautmann, 2001a, 2001b); Rhaetian of the Alps (Austria) (Tomašových, 2006a, 2006b), western Carpathians (Slovakia) (Tomašových, 2004), Austria and Germany (Hodges, 1991), England (Penarth Group) (Ivimey-Cook & others, 1999), Italy (Allasinaz, 1962); Early Jurassic; Hettangian of northwestern Europe (Hallam, 1987); early Liassic of South Wales (Hodges, 1991), Italy (Allasinaz, 1962).

  • Paleoautoecology.—B, E, S, C, Sed; C. Atreta was a cemented bivalve (fixed by its right valve) on other live invertebrates, such as sponges (Delvene, 2003; P. D. Taylor & Wilson, 2003), echinoids (Saint-Seine, 1951; Jagt, Neumann, & Schulp, 2007), other bivalves such as Plagiostoma, Gryphaea, Pinna, Antiquilima (Hodges, 1991), Indopecten (Hautmann, 2006a), Lopha, Cardinia, Myoconcha, and corals (Damborenea, 2002a). It is usually associated with other encrusting bivalves such as Liostrea (Hodges, 1991) or Lopha (Damborenea, 2002a). It was a gregarious bivalve, although it is rare to find it encrusting other individuals of the same species, and specimens are usually oriented with their dorsal part upward on sloping surfaces (Damborenea, 2002a).

  • Mineralogy.—Bimineralic (Malchus, 2000). Hodges (1991) did not find any shell preserved, and he believed it was likely that it was originally aragonitic. Malchus (2000) studied the microstructure of lower stages of excellently preserved Atreta specimens and found a foliated calcitic in outer shell layer and a well-developed cross-lamellar microstructure in the inner shell layer. Hautmann (2001a, 2006a) indicated that his specimens have a foliated calcite microstructure in the outer shell layer, and they did not have the inner one preserved. Outer shell layer: calcite (foliated). Inner shell layer: aragonite (cross-lamellar).

  • Figure 22.

    Paleogeographical distribution of Dimyidae (Afreta, Protostrea). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f22_01.jpg

    Genus PROTOSTREA Chen in Gu & others, 1976, p. 243

  • Type species.—Ostrea sinensis Hsu in Hsu & Chen, 1943, p. 136.

  • Remarks.—This genus was also called Proostrea (e.g., Skelton & Benton, 1993; Sepkoski, 2002) or Prostrea (e.g., Kobayashi & Tamura, 1983a) by mistake. Although its type species was originally included in Ostreoidea, following Morris in Skelton and Benton (1993), Komatsu, Akasaki, and others (2004), and J. Chen, Stiller, and Komatsu (2006), we include Protostrea in the Dimyidae (see J. Chen, Stiller, & Komatsu, 2006, for review and emendation of the genus). These authors interpreted Dimyodon qingyanensis Yin in Gan & Yin, 1978, as a juvenile stage of Protostrea sinensis and considered it the oldest member of the family Dimyidae.

  • Stratigraphic range.—Middle Triassic (Anisian) (J. Chen, Stiller, & Komatsu, 2006). Protostrea is a monospecific genus only known from the upper Anisian in the Qingyan formation (Stiller, 2000; Komatsu, Chen, & others, 2004; J. Chen, Stiller, & Komatsu, 2006).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 22).

  • Tethys domain; Middle Triassic; Anisian of southern China (Guizhou province) (Stiller, 2000; Komatsu, Akasaki, & others, 2004; J. Chen, Stiller, & Komatsu, 2006).

  • Paleoautoecology.—B, E, S, C, Sed; C. Protostrea sinensis probably lived cemented to the substrate by their right valve by a large cementation area (J. Chen, Stiller, & Komatsu, 2006). Often it is found cemented to other shells and corals (Komatsu, Chen, & others, 2004). Protostrea was also a substrate for other organisms, such as crinoids (Stiller, 2000).

  • Mineralogy.—Bimineralic. Not much is known about the shell mineralogy and microstructure of members of the family Dimyidae. Waller (1978) indicated that they may have had an inner shell layer of aragonite and cross-lamellar microstructure and that they do not have a simple prismatic calcitic layer. J. Chen, Stiller, and Komatsu (2006, p. 160) studied thin sections of their specimens, which, although recrystallized into calcite, “… the shells originally probably had a mainly crossed-lamellar microstructure (originally aragonitic); in parts (at least of right valves) there are relics of (an) irregular simple-prismatic outer layer (s) (originally calcitic).”

  • Figure 23.

    Paleogeographical distribution of Plicatulidae (Harpax, Eoplicatula, Pseudoplacunopsis). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f23_01.jpg

    Superfamily PLICATULOIDEA Watson, 1930
    Family PLICATULIDAE Watson, 1930
    Genus HARPAX Parkinson, 1811, p. 221

  • Type species.—Harpax parkinsoni Bronn, 1824, p. 52.

  • Remarks.—Although Harpax was considered a junior synonym of Plicatula Lamarck, 1801, by Cox and others (1969), some authors still regarded it as a valid subgenus of Plicatula (Okuneva, 1985; Damborenea, 1993; Aberhan, 1994a, 1998a; Gahr, 2002, among others). Recently, Damborenea (2002a) validated the genus, distinguishing it from Plicatula due to its hinge details, relative convexity of the valves, ornamentation, and ligament (see discussion in Damborenea, 2002a, p. 86–89). The hinge of many species attributed to Plicatula is unknown, and so species undoubtedly included in Harpax are: Harpax parkinsoni Bronn, 1824, Harpax rapa (Bayle & Coquand, 1851), Harpax kolymica (Polubotko in Kiparisova, Bychkov, & Polubotko, 1966), Harpax simplex Milova, 1976, Harpax spinosa (J. Sowerby, 1819), and Harpax auricula (Eudes-Deslongchamps, 1860), among others.

  • Stratigraphic range.—Upper Triassic (Norian)—Lower Jurassic (Toarcian) (Damborenea, 1993; Gahr, 2002). It is difficult to assign a specific range to this genus, since diagnostic characters (for example, the hinge) of many species are not known (Damborenea, 2002a). The oldest solid records are from the Norian (Okuneva, 1985; Damborenea, 1993), with the youngest being from the lower Toarcian of Spain and Portugal (Gahr, 2002). Hautmann (2001a, 2001b) considered the genus to be only present in the Lower Jurassic.

  • Paleogeographic distribution.—Boreal and Austral, ?Tethys (Fig. 23). Harpax had a bipolar distribution, at least during the Early Jurassic (Damborenea, 1993, 1996a, 2001). It originated in the Boreal domain during the Late Triassic. Later, during the Pliensbachian—Toarcian, it was also reported from the Tethys domain (Gahr, 2002). With some doubt, it was also reported from the Rhaetian—Hettangian boundary in Tibet (J. Yin & McRoberts, 2006) and from Sinemurian beds of Morocco (Tomašových, 2006c).

  • Boreal domain: Late Triassic: Norian of Siberia (Okuneva, 1985), northeastern Asia (Polubotko & Repin, 1990); Norian—Rhaetian of Siberia (Kiparisova, Bychkov, & Polubotko, 1966; Polubotko, 1968a; Bychkov & others, 1976); Early Jurassic: northeastern Russia (Milova, 1976); Hettangian of northeastern Asia (Polubotko & Repin, 1990); Hettangian—Sinemurian of Canada (Aberhan, 1998a; Aberhan, Hrudka, & Poulton, 1998).

  • Austral domain: Early Jurassic: Argentina (Damborenea, 1993, 2002a, 2002b); Hettangian—Sinemurian of Chile and Argentina (Damborenea, 1996a), ?New Zealand (Damborenea, 1993); Sinemurian of Chile (Aberhan, 1994a).

  • Paleoautoecology.—B, E, S, C, Sed; C. The distribution of bipolar (or antitropical) organisms is determined by temperature and substrate availability (Sha, 1996). They are abundant in shallow water areas at high latitudes and in deep water areas at low-latitude seas (Sha & Fürsich, 1994). According to several studies (see Damborenea, 2002a, p. 93), juvenile stages of Harpax were often cemented by the right valve to hard substrates (other shells, pebbles, rocks). However, in adult stages, they were often found loose in the sediment, so they had a free mode of life (Damborenea, 2002a). Sha (1996), based on various characters, such as the presence of byssal notch and sinus and pseudoctenolium, believed that in its juvenile stages, it also remained byssate, and he suggested that perhaps it had a pseudoplanktonic mode of life, attaching to floating objects (e.g., wood) or other swimming or nektonic organisms.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 226; Carter, Barrera, & Tevesz, 1998, p. 1003). Outer shell layer: calcite (foliated). Middle shell layer: calcite. Inner shell layer: aragonite.

  • Figure 24.

    Paleogeographical distribution of Pterinopectinidae (Ciarala), late Permian—Early Triassic.

    f24_01.jpg

    Genus EOPLICATULA Carter, 1990a, p. 221

  • Type species.—Plicatula imago Bittner, 1895, p. 213.

  • Stratigraphic range.—Upper Triassic (Carnian—Rhaetian) (Bittner, 1895; Hautmann, 2001a, 2001b). Carter (1990a) proposed Eoplicatula as a subgenus of Plicatula and only included the type species from the Carnian of Italy. Subsequently, Hautmann (2001a) included the species Plicatula difficilis Healey, 1908, from Rhaetian beds of Burma and Eoplicatula parvadehensis Hautmann, 2001a, from the Norian of Iran. Hautmann and others (2005) reported Eoplicatula from Rhaetian beds of southern Tibet but did not figure or describe the specimens.

  • Paleogeographic distribution.—Tethys (Fig. 23).

  • Tethys domain: Late Triassic: Carnian of Italy (Bittner, 1895; Leonardi, 1943; Carter, 1990a); Norian of Iran (Hautmann, 2001a, 2001b; Fürsich & Hautmann, 2005); Rhaetian of Burma (Healey, 1908).

  • Paleoautoecology.—B, E, S, C, Sed; C. Eoplicatula cemented to the substrate by its right valve. According to Hautmann (2001b), it was a reef-builder organism.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 223; Hautmann, 2001b). Outer shell layer: calcite (prismatic-foliated). Middle shell layer: aragonite (cross-lamellar). Inner shell layer: aragonite (prismatic—cross-lamellar).

  • Figure 25.

    Paleogeographical distribution of Aviculopectinidae (Eumorphotis, Ornithopecten, Oxypteria,Antijanira, Amphijanira,Primahinnites,Neomorphotis). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f25_01.jpg

    Genus PSEUDOPLACUNOPSIS Bittner, 1895, p. 215

  • Type species.—Pseudoplacunopsis affixa Bittner, 1895, p. 215.

  • Remarks.—After Todd and Palmer (2002), who proposed that Placunopsis Morris & Lycett, 1853 in 1851–1855, p. 5, is a genus belonging to the Jurassic family Anomiidae, several species that were traditionally attributed to this genus were rejected, as they did not have a byssal foramen, and they were regarded as terquemids (=prospondylids) instead. While Hölder (1990) considered species from Triassic and Cretaceous ages to be within Placunopsis, Todd and Palmer (2002) proposed that their affinities are uncertain, and their knowledge is based on new well-preserved materials. We believe that many of the Triassic species referred to Placunopsis and included into the family Terquemiidae Cox, 1964, among them the so-called false oyster, are, in fact, true plicatulids and should be referred to Pseudoplacunopsis. Checa and others (2003) resampled the Middle Triassic (Ladinian) localities studied by Schmidt (1935) and Márquez-Aliaga, Hirsch, and López-Garrido (1986) from the Betic ranges (Jaen), and they obtained several thousand specimens of Placunopsis flabellum Schmidt, 1935, in which only the calcite microstructure of the right valves (the cemented ones) was preserved. In tens of specimens, details of the hinge could be observed, showing an elongated ligament furrow bordered by two crura diverging from the beak and pits corresponding to the other valve crura and inserted below the hinge line. The external ornamentation presented antimarginal thick ribs, and thus the species was referred to Enantiostreon; but hinge characters indicate that P. flabellum was a true plicatulid. Subsequently, one of the authors (Márquez-Aliaga) found identical hinge characters in specimens from Ladinian beds of the Iberian range (Cuenca) attributed to Placunopsis teruelensis Wurm, 1911. This species is ornamented by fine ribs. There are many Middle Triassic nominal species assigned to this genus, which could, in fact, be regarded as synonyms due to the variability of the cemented valve. Among the finely ornamented species, P. plana (Giebel, 1856) from the Germanic Muschelkalk could include as synonyms the following names: alpina Winkler, 1859, schaflautli Winkler, 1859, teruelensis Wurm, 1911, and filicostata Hölder, 1990. Within the heavily ornamented species, matercula Quenstedt, 1852 in 1851–1852, could include as a synonym flabellmn Schmidt (Checa & others, 2003). Recently, Posenato (2008b) developed similar ideas.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Rhaetian) (Posenato, 2008b; Márquez-Aliaga, Damborenea, & Goy, 2008a). Cox and others (1969) assigned it an Upper Triassic range, and Hautmann (2001a) also considered that it ranged from the Carnian, but new records, as discussed above, confirmed its presence in Middle Triassic deposits. Regarding the upper extension of its stratigraphic range, Hautmann (2001a) considered that Pseudoplacunopsis lived until Kimmeridgian times, represented by the species Plicatula ogerieni Loriol, 1904. Hautmann (2001a) did not make any comments about this species, nor did we find any record of the genus for the Jurassic; and its last appearance seems to be Rhaetian. It is interesting to note that most references to this genus are based on the diagnosis given by Bittner (1895) and Cox (1924), and not on the emended one by Hautmann (2001a), as the hinge and the ligament area are rarely preserved in specimens attributed to this genus.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 23).

  • Tethys domain: Middle Triassic: Anisian of Italy (Posenato, 2008b); Ladinian of Spain (Schmidt, 1935; Márquez-Aliaga, 1985; Martínez & Márquez-Aliaga, 1992; López-Gómez & others, 1994; Márquez-Aliaga & Ros, 2002; Márquez-Aliaga, Budurov, & Martínez, 1996; Márquez-Aliaga & others, 2004), Germany (Hagdorn & Simon, 1983; Hölder, 1990), France (Brocard & Philip, 1989), Israel (Lerman, 1960), Poland (Assmann, 1916), Italy (Posenato, 2002), Jordan (Cox, 1924); Late Triassic: Carnian of Spain (Martín-Algarra, Solé de Porta, & Márquez-Aliaga, 1995), Italy (Bittner, 1895; Leonardi, 1943); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Austria (Posenato, 2008b), Spain (Márquez-Aliaga, Damborenea, & Goy, 2008b; Márquez-Aliaga & others, 2010).

  • Circumpacific domain: Middle Triassic: Ladinian of Nevada (United States) (Waller in Waller & Stanley, 2005).

  • Paleoautoecology.—B, E, S, C, Sed; C. Pseudoplacunopsis was a cementing bivalve. It attached to the substrate by its right valve, and according to Hautmann (2001a), it was a reef builder. Márquez-Aliaga and Martínez (1994) studied its behavior as an epizoan organism.

  • Mineralogy.—Bimineralic (De Renzi & Márquez-Aliaga, 1980; Márquez-Aliaga & Márquez, 2000). Outer shell layer: calcite (foliated). Inner shell layer: aragonite (cross-lamellar).

  • Superfamily PTERINOPECTINOIDEA Newell, 1938
    Family PTERINOPECTINIDAE Newell, 1938
    Genus CLARAIA Bittner, 1901a, p. 568

  • Type species.—Posidonomya clarae Hauer, 1850, p. 112.

  • Remarks.—Several taxa related to Claraia will not be considered in this analysis for various reasons: either they are regarded as synonyms of Claraia or their separation at generic level is not justified. These taxa are: Pseudoclaraia Zhang, 1980, p. 438, 443, Pteroclaraia Guo, 1985, p. 150, 265, Guichiella J. Li & Ding, 1981, p. 328–329, Claraioides Z. Fang, 1993, p. 653, 660, Epiclaraia Gavrilova, 1995, p. 156, and Rugiclaraia Waterhouse, 2000, p. 179 (see discussion for each of them in Genera not Included, p. 156).

  • Stratigraphic range.—upper Permian (Wuchiapingian)—Lower Triassic (middle Olenekian) (F. Yang, Peng, & Gao, 2001; McRoberts, 2010). For a long time, Claraia was regarded as a Lower Triassic index fossil. Cox and others (1969) assigned it a Lower Triassic range with a cosmopolitan distribution. Later, Nakazawa and others (1975) reported Claraia bioni Nakazawa in Nakazawa & others, 1975, from upper Permian sediments. Since then, there were many new upper Permian records (H. Yin, 1983; F. Yang, Peng, & Gao, 2001; Z. Fang, 1993, 2003; Gao, Yang, & Peng, 2004; Kotlyar, Zakharov, & Polubotko, 2004; He, Feng, & others, 2007; He, Shi, & others, 2007). Boyd and Newell (1979) reported Claraia? posidoniformis Termier & Termier, 1977, from Tunisian Guadalupian beds, but they doubted the generic relations of this species, because it shows some features that are not typical of Claraia.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 24). During the late Permian, Claraia was widely distributed, mainly in the eastern part of Tethys. During the Early Triassic, it was abundant almost everywhere that beds of this age occur. For this reason, even though it was not reported from certain areas, a cosmopolitan distribution is given.

  • Tethys domain: late Permian: Kashmir (India) (Nakazawa & others, 1975); Wuchiapingian of China (F. Yang, Peng, & Gao, 2001); Changhsingian of China (Z. Zhang, 1980; H. Yin, 1983, 1990; Z. Fang, 1993, 2003; F. Yang, Peng, & Gao, 2001; Gao, Yang, & Peng, 2004; Z. Chen, Kaiho, & others, 2006; He, Feng, & others, 2007; He, Shi, & others, 2007), northwestern Caucasus (Russia) (Kotlyar, Zakharov, & Polubotko, 2004; Ruban, 2006a); Early Triassic: Pamir (Afghanistan) (Polubotko, Payevskaya, & Repin, 2001), Himalayas (Nepal) (Waterhouse, 2000), Italy (Leonardi, 1935; Broglio-Loriga, Masetti, & Neri, 1982; Neri, Pasini, & Posenato, 1986; Broglio-Loriga & others, 1988, 1990; Posenato, 1988; Posenato, Sciunnach, & Garzanti, 1996; Fraiser & Bottjer, 2007a, 2007b), China (Hsu, 1936–1937; F. Wu, 1985; Z. Li & others, 1986; Lu & Chen, 1986; S. Yang, Wang, & Hao, 1986; Z. Yang & others, 1987; Ling, 1988; M. Wang, 1993; Tong & Yin, 2002), Ussuriland (Russia) (Kiparisova, 1938); Induan of China (C. Chen, 1982; F. Yang, Peng, & Gao, 2001; He, Feng, & others, 2007), Italy (Leonardi, 1960), Malaysia (Ichikawa & Yin, 1966; Tamura & others, 1975), Vietnam (Vu Khuc & Huyen, 1998), Alberta (Canada) (Newell & Boyd, 1995; McRoberts, 2010); Olenekian of Mangyshlak (Kazakhstan) (Gavrilova, 1995), China (H. Yin, 1990; J. Chen & Komatsu, 2002), Pakistan (Nakazawa, 1996), Vietnam (Komatsu & Huyen, 2006).

  • Circumpacific domain: Early Triassic: Wyoming and Idaho (United States) (Newell & Kummel, 1942), Alberta (Canada) (Newell & Boyd, 1970), Japan (Nakazawa, 1971; Hayami, 1975); Induan of Nevada (United States) (Ciriacks, 1963; Schubert, 1993; Newell & Boyd, 1995; Schubert & Bottjer, 1995; Boyer, Bottjer, & Droser, 2004; Fraiser & Bottjer, 2007a, 2007b).

  • Boreal domain: late Permian: eastern Greenland (Newell & Boyd, 1995), Nova Zemla (Arctic Ocean) (Muromtseva, 1984); Early Triassic: Queen Elizabeth Islands (Arctic Archipelago, Canada) (Tozer, 1961, 1962, 1970).

  • Paleoautoecology.—B-Ps, E, S, Epi, Se-FaM. Several modes of life have been attributed to Claraia, ranging from benthic epibyssate (Z. Fang, 1993; F. Yang, Peng, & Gao, 2001) to pseudoplanktonic and even occasional swimmer (F. Yang, Peng, & Gao, 2001). Claraia shell morphology subtly changed through time. These differences are primarily related to the morphology of the byssal notch, the ornamentation, and the shape of the auricles (F. Yang, Peng, & Gao, 2001; He, Feng, & others, 2007). Permian forms had a more developed and deep byssal notch, shells were small in size, thin, and slightly inequivalve; they were interpreted as living epibyssate with the capacity to swim occasionally (F. Yang, Peng, & Gao, 2001). However, due to the associated fauna, e.g., ammonoids, they were also interpreted as pseudoplanktonic (H. Yin, 1983). Nevertheless, according to F. Yang, Peng, and Gao (2001), features present in Permian forms were unsuited to this mode of life. On the other hand, in the Triassic forms, the byssal notch was shallower, which is associated with increased mobility (Z. Fang, 1993; see also He, Feng, & others, 2007, table 1), and the shells were less ornamented (F. Yang, Peng, & Gao, 2001). These forms were also interpreted by F. Yang, Peng, and Gao (2001) as being pseudoplanktonic bivalves that attached themselves to pieces of wood or algae.

  • The genus occurred primarily in deep-water Permian deposits, but, by the Triassic, it was in all types of environments, from shallow to deep (F. Yang, Peng, & Gao, 2001). This fact was related to an opportunistic behavior during recovery from the Permian—Triassic (P/T) extinction event (Schubert & Bottjer, 1995; Rodland & Bottjer, 2001). This success during the Triassic appears to be related to the morphological change, since Permian forms with a deep byssal notch did not survive the P/T event; however, the forms with a shallower byssal notch diversified enormously [from 3 species in late Permian to over 30 in the Triassic (He, Feng, & others, 2007)]. According to F. Yang, Peng, and Gao (2001), this was also related to the mode of life of Claraia larvae, which probably had a veliger planktonic stage. The deep-water habitats in which mostly Permian forms were found were interpreted by Gao, Yang, and Peng (2004) as potential refuges for those forms that survived and reached the Early Triassic. It is hard to assign a unique mode of life to all species of Claraia, since they have a wide range of morphological features that suggests that some species could have been epibenthic, pseudoplanktonic, and even occasional swimmers (He, Feng, & others, 2007).

  • Mineralogy.—Bimineralic (Boyd & Newell, 1976; Newell & Boyd, 1985, 1995; Carter, 1990a, 1990b). Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (?).

  • Superfamily AVICULOPECTINOIDEA Meek & Hayden, 1864
    Family AVICULOPECTINIDAE Meek & Hayden, 1864
    Genus EUMORPHOTIS Bittner, 1901a, p. 566

  • Type species.—Pseudomonotis telleri Bittner, 1898, p. 710.

  • Stratigraphic range.—Lower Triassic (Induan—Olenekian) (Broglio-Loriga & Mirabella, 1986). Cox and others (1969) assigned it a Lower Triassic—Upper Triassic range. However, Broglio-Loriga and Mirabella (1986) did a comprehensive study on Eumorphotis, and they noted that Middle and Upper Triassic forms were highly dubious, and therefore they restricted the range of Eumorphotis to the Lower Triassic. Newell and Boyd (1995) assigned it the same range. Furthermore, these authors argued that Heteropecten Kegel & Costa, 1951, and Eumorphotis were virtually indistinguishable and that the reason for proposing Eumorphotis was more to separate the Paleozoic from the Triassic forms than to recognize significant morphological differences between the two groups. In fact, Newell and Boyd (1995) considered that some specimens attributed by Bittner (1901b) to the Triassic Eumorphotis from eastern Siberia are similar to Heteropecten. Moreover, Eumorphotis was also reported from the upper Permian, but Broglio-Loriga and Mirabella (1986) doubted all these records, because they were based on poorly preserved material. Posenato, Pelikán, and Hips (2005) proposed a new species, Eumorphotis lorigae Posenato, Pelikán, & Hips, 2005, and they referred it to the upper Permian (upper Changhsingian), but, as indicated by the authors, this age is only provisionally based on bivalves and brachiopods, and thus we will not take this record into account until new data allow a more precise age determination.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 25).

  • Tethys domain: Early Triassic: Italy (Bittner, 1912; Leonardi, 1935; Broglio-Loriga, Masetti, & Neri, 1982; Neri & Posenato, 1985; Broglio-Loriga & Mirabella, 1986, and references therein; Neri, Pasini, & Posenato, 1986; Broglio-Loriga & others, 1990), Ussuriland (Russia) (Kiparisova, 1938), Vietnam (Vu Khuc & Huyen, 1998), Pakistan (Nakazawa, 1996), Malaysia (Ichikawa & Yin, 1966), China (Hsu, 1936–1937; Z. Yang & Yin, 1979; C. Chen, 1982; F. Wu, 1985; S. Yang, Wang, & Hao, 1986; Ling, 1988; H. Yin, 1990; Tong & others, 2006); Induan of southern China (Hautmann & others, 2011).

  • Circumpacific domain: Early Triassic: western United States and Japan (Newell & Kummel, 1942; Ciriacks, 1963; Schubert, 1993; Newell & Boyd, 1995; Boyd, Nice, & Newell, 1999; Fraiser & Bottjer, 2007a), Japan (Nakazawa, 1961, 1971; Hayami, 1975; Kashiyama & Oji, 2004).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to key features present in different species of this genus (elongated anterior auricles, byssal notch in adults), and, following S. M. Stanley's (1970, 1972) criteria, Eumorphotis could be an epibyssate bivalve. Together with Claraia, Promyalina, and Unionites, Eumorphotis was one of the dominant bivalves in the Early Triassic seas (Fraiser & Bottjer, 2007a).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 241). There are no available data about Eumorphotis shell mineralogy or microstructure. Data provided for family Aviculopectinidae. Outer shell layer: calcite (prismatic-homogeneous-foliated). Inner shell layer: aragonite (nacreous—cross-lamellar).

  • Genus ORNITHOPECTEN Cox, 1962, p. 596

  • Type species.Aviculopecten bosniae Bittner, 1903, p. 592.

  • Remarks.—Cox (1962) proposed Ornithopecten to accommodate several Triassic species that were previously attributed to Aviculopecten M'Coy, 1851, p. 171 (which is actually regarded a strictly Paleozoic genus).

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Diener, 1923; Allasinaz, 1972). Cox and others (1969) assigned it a Middle—Upper Triassic range. According to Diener (1923), the species assigned to Ornithopecten by Cox (1962) were reported from Anisian and Carnian beds. Subsequently, the genus was reported from the Lower Triassic of China, but there are several problems with these records. The only reference we could locate in which the material was described and figured is Z. Yang and others (1987). A new species was described there: Ornithopecten? magnauritus Yin, but this was only doubtfully assigned to Ornithopecten, and, as noted by the authors, it might be better located within Eumorphotis Bittner, 1901a, with which we agree. The other papers where the genus was mentioned from the Triassic age (e.g., Z. Chen, Shi, & Kaiho, 2004; Z. Chen & McNamara, 2006; Z. Chen, Shi, & others, 2006) do not have figures or descriptions; furthermore, they do not mention the original source of data, so they are not taken into account.

  • Paleogeographic distribution.—Tethys (Fig. 25).

  • Tethys domain: Middle Triassic: Anisian of Yugoslavia (Allasinaz, 1972), China (H. Yin, 1985; J. Chen & Stiller, 2007), Alps (Diener, 1923); Ladinian of China (H. Yin, 1985), southern Alps (Bittner, 1895; Diener, 1923); Late Triassic: Carnian of the Alps (Diener, 1923).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Following the guidelines provided by S. M. Stanley (1970, 1972), Ornithopecten was most likely an epibyssate bivalve, and the byssus was placed under the anterior auricle.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 241). There are no data about Ornithopecten shell. Data provided for family Aviculopectinidae. Outer shell layer: calcite (prismatic-homogeneous-foliated). Inner shell layer: aragonite (nacreous—cross-lamellar).

  • Genus OXYPTERIA Waagen, 1907, p. 93

  • Type species.—Aviculopecten (Oxypteria) bittneri Waagen, 1907, p. 93.

  • Stratigraphic range.—Upper Triassic (Carnian) (Cox & others, 1969). Waagen (1907) proposed the genus on the basis of material from Carnian beds of southern Tyrol. The only other references that could be located are Diener (1923) and Cox and others (1969), who repeated the information in Waagen.

  • Paleogeographic distribution.—western Tethys (Fig. 25).

  • Tethys domain: Late Triassic: Carnian of southern Tirol (Italian Alps) (Waagen, 1907; Diener, 1923; Cox & others, 1969).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Since all that is known of this monospecific genus is a left valve, it is difficult to speculate how it lived. We assign it the dominant mode of life in the family Aviculopectinidae.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 241). There are no data about Oxypteria shell. Data provided for family Aviculopectinidae. Outer shell layer: calcite (prismatic-homogeneous-foliated). Inner shell layer: aragonite (nacreous—cross-lamellar).

  • Genus ANTIJANIRA Bittner, 1901c, p. 49

  • Type species.Pecten hungaricus Bittner, 1901c, p. 48.

  • Remarks.—According to Allasinaz (1972), Bittner proposed the name Antijanira to accommodate a group of Triassic species with a particular ornamentation type. However, Bittner did not provide a true diagnosis, nor did he indicate the similarities and differences with other taxa (Allasinaz, 1972). Probably for this reason, Newell and Boyd (1995) placed Antijanira in synonymy with Leptochondria Bittner, 1891, p. 101. Allasinaz (1972) provided an adequate diagnosis and discussed its similarities with other taxa, so the genus will be considered valid here and included in the Aviculopectinidae, according to this author. Cox and others (1969) and Carter (1990a) regarded it a member of Pectinidae, as did other authors (Kobayashi & Tamura, 1983a; Gou, 1993), who also considered it a subgenus of Chlamys Röding in Bolten, 1798. However, Johnson and Simms (1989) suggest allocation in Aviculopectinidae is supported by the shell structure and the aviculopectinid-type ligament.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Allasinaz, 1972). Cox and others (1969) assigned it an Upper Triassic range in Hungary and Sepkoski (2002) a Triassic (Anisian—Carnian) range, taking data from Hallam (1981), who considered it to be present only in the European Carnian, and Hayami (1975), who reported it from Anisian and Ladinian beds. Although the Anisian records appeared in Bittner (1903), Cox and others (1969) did not take them into account. On the other hand, Allasinaz (1972) did consider them, and we follow him.

  • Paleogeographic distribution.—western Tethys (Fig. 25). The distribution of this genus was limited to the Tethys domain. Waller and Stanley (1998) found a fragment of scallop that could be attributed to Antijanira amphidoxa (Bittner, 1903) from Middle Triassic beds of Nevada, but Waller and Stanley (2005) later included this specimen in Oxytoma (Oxytoma) grantsvillensis Waller in Waller & Stanley, 2005. Although Antijanira was reported from the Upper Triassic of China (Kobayashi & Tamura, 1983a; Gou, 1993), we cannot be sure of its presence in this area, since the only available described and figured specimens appeared in Gou (1993), and neither the auricles nor the ligament area are seen in them; moreover, neither the description nor the ornamentation match with the diagnosis given by Allasinaz (1972). Z. Fang and others (2009) tentatively suggested Halobia (Enormihalobia) Yin & Gan in Gan & Yin, 1978, p. 352, is a junior synonym of Antijanira. If this synonymy is accepted, the distribution of Antijanira extended to the Eastern Tethys (Carnian of Guizhou province).

  • Tethys domain; Middle Triassic; Anisian of Yugoslavia (Bittner, 1903; Allasinaz, 1972); Late Triassic; Carnian of Alps (Italy) (Bittner, 1895, 1901a; Allasinaz, 1972; Johnson & Simms, 1989), Tripoli-Garian region (Libya) (Desio, Rossi Ronchetti, & Vigano, 1960), Hungary (Bittner, 1912).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to S. M. Stanley (1970), bivalves that are able to swim possess a symmetrical shell, equal auricles, and an umbonal angle greater than 105°. In the specimens described by Allasinaz, the umbonal angle is usually about 90°, but the angles given by Allasinaz (1972, p. 275) for some specimens from Zardini's collection often exceed 100° and even reach 115°. However, the auricles are not equal (see description in Allasinaz, 1972, p. 271), and in the anterior one, there is a deep byssal groove; also, not all species have a perfectly symmetrical shell, so it is likely that Antijanira species lived epibyssate with the sagittal plane in a horizontal position, interpreted by S. M. Stanley (1970) as being very stable since it increases the surface area in contact with the substrate. In addition, the auricles of these species have different convexity, suggesting they were not well adapted for swimming (S. M. Stanley, 1970).

  • Mineralogy.—Bimineralic (Allasinaz, 1972; Carter, 1990a, p. 255, 262). Allasinaz (1972) described the shell microstructure of Antijanira with an external shell layer of prismatic calcite in the right valves and fibrous in the left. Carter (1990a) described the microstructure of the group Antijanira as grade 2. Although there are differences between the valves, the outer layer is always calcitic and the middle and inner layers are aragonitic. Outer shell layer: calcite (prismatic-homogeneous). Middle and inner shell layers; aragonite (cross-lamellar).

  • Genus AMPHIJANIRA Bittner, 1901c, p. 49

  • Type species.Pecten janirula Bittner, 1895, p. 160.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Allasinaz, 1972). The range provided by both Cox and others (1969) and Sepkoski (2002) is similar to Antijanira (see stratigraphic range for Antijanira). Following Allasinaz (1972), we assign a Anisian—Carnian range.

  • Paleogeographic distribution.—western Tethys (Fig. 25).

  • Tethys domain; Middle Triassic; Anisian of Yugoslavia (Bittner, 1903; Allasinaz, 1972); Late Triassic; Carnian of the Alps (Italy) (Bittner, 1895; Allasinaz, 1972).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Amphijanira had an equivalve shell, the auricles were very different, with the posterior one being smaller and separated from the shell and the anterior one with a pronounced byssal notch (Allasinaz, 1972), and thus it is very unlikely that it could swim. It probably lived attached by the byssus.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 255, 262). Although there are no specific data for Amphijanira shells, we assign the same data as Antijanira, following Carter, who provided the same information for the entire Antijanira Group. Outer shell layer: calcite (prismatic-homogeneous). Middle shell layer: aragonite (cross-lamellar). Inner shell layer: aragonite (cross-lamellar).

  • Genus PRIMAHINNITES Repin, 1996, p. 367

  • Type species.Primahinnites iranica Repin, 1996, p. 367.

  • Remarks.—Repin (1996) included Primahinnites within the family Prospondylidae, but he only had a complete right valve and five fragments of right and left valves. Hautmann (2001b) obtained new and better preserved material, in which he observed certain key features, such as the ctenolium, and he included the genus in the family Aviculopectinidae; indeed, he emended the diagnosis. Repin's (1996) allocation was erroneous because none of his specimens had the cementation area preserved, but they had a byssal notch instead, described as being small (Hautmann, 2001b).

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (Hautmann, 2001b). Although originally Repin (1996) reported Primahinnites only from the upper Norian, later Hautmann (2001b) reported it from the Rhaetian as well.

  • Paleogeographic distribution.—Tethys (Fig. 25).

  • Tethys domain: Late Triassic: Norian of Iran (Repin, 1996; Hautmann, 2001b); Rhaetian of Iran (Hautmann, 2001b).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Hautmann (2001b) described a well-developed byssal notch below the anterior auricle of the right valve, so he considered it to be an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 241). There are no data about Primahinnites shell mineralogy. Data provided for family Aviculopectinidae. Outer shell layer: calcite (prismatic-homogeneous-foliated). Inner shell layer: aragonite (nacreous—cross-lamellar).

  • Genus NEOMORPHOTIS H. Yin & Yin, 1983, p. 155

  • Type species.Neomorphotis gigantea H. Yin & Yin, 1983, p. 155. This species was regarded as a synonym of Eumorphotis buhaheensis Lu by Fang & others, 2009, p. 36.

  • Remarks.Neomorphotis was originally included in the family Pectinidae, but H. Yin (1985) and Posenato (2008b) transferred it to Aviculopectinidae. Due to its relationship with Eumorphotis, this seems appropriate.

  • Stratigraphic range.—Middle Triassic (Anisian) (Posenato, 2008b). According to Z. Fang and others (2009), the genus was proposed by H. Yin and Yin in 1983 from Middle Triassic beds of China. All records are from the Anisian (e.g., Lu & Chen, 1986; Ling, 1988; Sha, Chen, & Qi, 1990; Posenato, 2008b), but we are not certain which species were included in the genus by the authors, and thus the range will remain temporarily as Anisian until we have access to more information.

  • Posenato (2008b) raised the possibility that Pseudomonotis beneckei Bittner, 1900 (according to this author, included by H. Yin & Yin in Neomorphotis) is a junior synonym Neomorphotis compta (Goldfuss, 1833 in 1833–1841). If we accept this synonymy, the genus would be also present in the Lower Triassic, as P. beneckei was mentioned for this age by several authors. However, we included this species in Eumorphotis following Broglio-Loriga and Mirabella (1986). H. Yin (1985) considered that the genus was also present in the Olenekian, data incorporated by Sepkoski (2002).

  • Paleogeographic distribution.—Tethys (Fig. 25).

  • Tethys domain: Middle Triassic: Anisian of the Dolomites (Italy) (Posenato, 2008a, 2008b), southern China (Lu & Chen, 1986; Ling, 1988; Sha, Chen, & Qi, 1990).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. At least N. compta, according to the description offered by Posenato (2008b), probably was an epibyssate bivalve, since it has an inequivalve shell and a deep byssal notch in the right valve. Moreover, taphonomic evidence also supports this mode of life (see Posenato, 2008b, p. 101).

  • Mineralogy.—Bimineralic (Posenato, 2008b). Posenato (2008b, p. 101) indicated about N. compta (Goldfuss, 1833 in 1833–1841): “shell wall is thin, bimineralic, and consisting of an outer calcitic layer and an inner, thin, calcitized layer.”

  • Figure 26.

    Paleogeographical distribution of Deltopectinidae (Crittendenia, Streblopteria). 1, Early Triassic; 2, Middle Triassic.

    f26_01.jpg

    Family DELTOPECTINIDAE Dickins, 1957
    Genus CRITTENDENIA Newell, & Boyd, 1995, p. 52

  • Type species.Crittendenia kummeli Newell & Boyd, 1995, p. 53.

  • Remarks.—Newell and Boyd (1995) provisionally included their new genus in Deltopectinidae due to external similarities with Streblopteria M'Coy, 1851, in the absence of characters from the ligament area and microstructure of the shell. Besides the type species, recorded from the Thaynes Formation in Nevada, they also included Pseudomonotis decidens Bittner, 1899, which was referred to Claraia and Streblopteria by other authors (see Newell & Boyd, 1995, p. 52–53). Gavrilova (1996), ignoring Newell and Boyd's paper, proposed a new subgenus of Claraia, Bittnericlaraia Gavrilova, with Pseudomonotis decidens Bittner, 1899, as type.

  • Newell and Boyd (1995) have a few contradictions, however: in the text, they mentioned P. decidens as being collected in Salt Range, Pakistan, and referred it to their figure 39. In this figure explanation, the given name is Crittendenia kummeli from the Lower Triassic of Salt Range, Pakistan. Furthermore, they considered C. kummeli as being present in Nevada and in Pakistan. This was used by Nakazawa (1996) to regard C. kummeli as a synonym of B. decidens. But taking into account that the ligament area is not known in any of these species, this synonymy is not clearly justified (Waterhouse, 2000). Waterhouse (2000) saw a clear relationship between Claraia and Crittendenia, and he referred the latter to the Pterinopectinidae. Furthermore, this author included in Crittendenia several new species, plus those included by Gavrilova (1996) in Claraia (Bittnericlaraia), but Waterhouse had a concept of the genus that is totally different from the original authors. In the absence of more information about key characters of the genus, as discussed above, we provisionally accept the allocation of Newell and Boyd (1995).

  • Stratigraphic range.—Lower Triassic (Newell & Boyd, 1995). Crittendenia was only reported from Lower Triassic (Newell & Boyd, 1995).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 26).

  • Tethys domain: Early Triassic: Pakistan (Newell & Boyd, 1995), Himalayas (Bittner, 1899), Nepal (Waterhouse, 2000).

  • Circumpacific domain: Early Triassic: Nevada (United States) (Newell & Boyd, 1995; Fraiser & Bottjer, 2007a).

  • Paleoautoecology.—B-Ps, E, S, Epi, Sed-FaM; By. Newell and Boyd (1995) mentioned a deep byssal notch in Crittendenia diagnosis, so this is an epibyssate bivalve. In addition, it was often found in association with ammonoids, and the umbilical area of ammonoids is sometimes xenomorphic on the bivalve shell. Therefore, Newell and Boyd (1995) postulated that Crittendenia could have had a pseudoplanktonic (attached to objects by the byssus) or even pseudopelagic mode of life (attached by byssus to the shells of live ammonoids).

  • Mineralogy.—Bimineralic (Waller, 1978). There are no data on the mineralogy and microstructure of Crittendenia shell. Due to the uncertainties about its familial assignation, we cannot use here the predominant data from the family. In the diagnosis provided by Waller (1978) for the order Pectinoida, he indicated that the shell is bimineralic.

  • Figure 27.

    Paleogeographical distribution of Leptochondrndae (Leptochondria). 1, late Permian—Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f27_01.jpg

    Genus STREBLOPTERIA M'Coy, 1851, p. 170

  • Type species.Meleagrina laevigata M'Coy, 1844, p. 80.

  • Stratigraphic range.—Carboniferous (Mississippian)—Middle Triassic (Anisian) (Dagys & Kurushin, 1985; Newell & Boyd, 1995). Streblopteria is a distinctive Paleozoic genus (Newell, 1938; Nakazawa & Newell, 1968; Hayami & Kase, 1977; Waterhouse, 1978; Boyd & Newell, 1979; Newell & Boyd, 1987, among others). However, Newell and Boyd (1995, p. 50) argued that it was also reported from the Middle Triassic of Siberia: “Distribution: Cosmopolitan, Miss.-Perm., M. Trias, of Arctic Siberia (fide Kurushin, 1982, p. 60).” In fact, ten years earlier, Dagys and Kurushin (1985) had described and listed the species referred by Newell and Boyd (1995): Streblopteria newelli Kurushin, 1982, and a new species, S. jakutica Kurushin in Dagys & Kurushin, 1985, the first being reported from the Olenekian and Anisian and the second from the Olenekian.

  • Paleogeographic distribution.—Boreal (Fig. 26). During the Carboniferous and the Permian, it had a cosmopolitan distribution (Newell & Boyd, 1995). Specifically, it was reported from the upper Permian of Nepal (Waterhouse, 1978), China (H. Yin, 1983; Z. Yang & others, 1987; M. Wang, 1993; He, Feng, & others, 2007), and the boreal region of Russia (Astafieva, 1998).

  • Boreal domain: Early Triassic: Olenekian of northern Siberia (Dagys & Kurushin, 1985); Middle Triassic: Anisian of northern Siberia (Dagys & Kurushin, 1985).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Within pectinoids, two groups can be recognized regarding their mode of life (S. M. Stanley, 1972): epibyssate bivalves, which are characterized by different convexity in both valves, the anterior auricle being more developed than the posterior one, and having a byssal sinus throughout its ontogeny; and others, also epibyssate but which developed swimming abilities, which are more symmetrical with both valves being equally convex, with auricles of the same shape and size, and an umbonal angle greater than 90°. Streblopteria features indicate it belongs in the first group.

  • Mineralogy.—Bimineralic (Waller, 1978). According to Newell and Boyd (1985), the outer shell layer of Streblopteria was fibrous prismatic in both valves. The inner shell layers are not known, but Waller (1978), in the diagnosis of the order Pectinioida, indicated that the shell was bimineralic.

  • Superfamily PSEUDOMONOTOIDEA Newell, 1938
    Family LEPTOCHONDRIIDAE Newell & Boyd, 1995
    Genus LEPTOCHONDRIA Bittner, 1891, p. 101

  • Type species.Pecten aeolicus Bittner, 1891, p. 101.

  • Stratigraphic range.—middle Permian (Guadalupian)—Upper Triassic (Norian) (Cox, 1949; Newell & Boyd, 1995). Although Cox and others (1969) assigned it a Lower—Upper Triassic range, new records expanded the range of this genus. Leptochondria was reported from the middle Permian of Texas and Wyoming (United States) (Boyd & Newell, 1995) and from the upper Permian (Nakazawa & Newell, 1968; He, Feng, & others, 2007). Waller and Stanley (2005) reported Leptochondria from upper Permian of Pakistan, allegedly taking their data from Newell and Boyd (1995), but there the genus was mentioned only from the Lower Triassic of Pakistan. The youngest record is Norian (Cox, 1949; Newell & Boyd, 1995).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 27).

  • Tethys domain: late Permian: Changhsingian of southern China (Y. Zhang, 1981; H. Yin, 1983; He, Feng, & others, 2007); Early Triassic: Induan of Pakistan (Nakazawa, 1996); Olenekian of southern China (Sha, 1995, 1998; Sha & Grant-Mackie, 1996; Sha, Johnson, & Fürsich, 2004), Italy (Neri & Posenato, 1985; Posenato, 2008a); Middle Triassic: Poland (Senkowiczowa, 1985); Anisian of Italy, Yugoslavia, and Bulgaria (Allasinaz, 1972), southern China (Komatsu, Chen, & others, 2004); Anisian—Ladinian of Hungary (Szente, 1997), northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of Italy (Allasinaz, 1972), Spain (Márquez-Aliaga, 1983, 1985; Márquez-Aliaga, Hirsch, & López-Garrido, 1986; Márquez-Aliaga & Montoya, 1991; Freneix, 1999; Niemeyer, 2002; Márquez-Aliaga & Ros, 2003), Carpathians (Slovakia) (Kochanová, Mello, & Siblík, 1975); Late Triassic: Carnian of Italy and Yugoslavia (Allasinaz, 1972); Norian of Hungary (Allasinaz, 1972), Anatolia (Turkey) (Diener, 1923).

  • Circumpacific domain: late Permian; Japan (Nakazawa & Newell, 1968; Hayami, 1975; Hayami & Kase, 1977); Early Triassic; Ussuriland (Russia) (Kiparisova, 1938); Olenekian of Nevada (United States) (Newell & Boyd, 1995; Boyer, Bottjer, & Droser, 2004; Fraiser & Bottjer, 2007a), Utah (United States) (Boyer, Bottjer, & Droser, 2004; Fraiser & Bottjer, 2007a), Japan (Nakazawa, 1961, 1971; Fraiser & Bottjer, 2007a); Middle Triassic; Ladinian of Nevada (United States) (Waller & Stanley, 2005); Late Triassic; Norian of Peru (Cox, 1949).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the diagnosis provided by Newell and Boyd (1995), there is a wide byssal notch in the right valve. It was most likely an epibyssate bivalve. Sha and Grant-Mackie (1996) proposed a possible pseudoplanktonic mode of life for Leptochondria.

  • Mineralogy.—Bimineralic (Waller & Stanley, 2005). Waller and Stanley (2005) assumed bimineralic mineralogy, due to the differential dissolution of the shell layers in their specimens of Leptochodria shoshonensis Waller in Waller & Stanley, 2005.

  • Figure 28.

    Paleogeographical distribution of Buchiidae (Bittneria, Hokonuia, Sichuania, Marwickiella, Anningella). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f28_01.jpg

    Superfamily MONOTOIDEA Fischer, 1887 in 1880–1887
    Family BUCHIIDAE Cox, 1953
    Genus BITTNERIA Broili, 1904, p. 168

  • Type species.Avicula? efflata Broili, 1904, p. 167.

  • Remarks.—Broili (1904) proposed the genus Bittneria based on Avicula? efflata, and he included it in the family Aviculidae, although he noted that it could be considered as being intermediate between Avicula and Pecten. This allocation is doubtful, because only one left valve was then available. Subsequently, Cox and others (1969) included it in the family Buchiidae, also dubiously. The systematic position of this genus is especially problematic, because the hinge structure is not known (Sha & Fürsich, 1994). These authors related Bittneria to Aucellina Pompeckj, 1901.

  • Stratigraphic range.—Upper Triassic (Carnian) (Broili, 1904). The genus was proposed by Broili (1904) as being from Carnian sediments, and little else is known about it. Cox and others (1969) assigned the same range. Subsequently, new material was found at the same stage by Fürsich and Wendt (1977).

  • Paleogeographic distribution.—western Tethys (Fig. 28). Although J. Chen (1982a) described a new species from the Carnian of southern China (Bittneria? hunanensis]. Chen, 1982a), it was only doubtfully assigned to the genus, so we are not considering it.

  • Tethys domain: Late Triassic: Carnian of southern Alps (Broili, 1904; Waagen, 1907; Fürsich & Wendt, 1977).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the diagnosis offered by Cox and others (1969), the anterior left auricle is separated from the disk by a deep sinus from where the byssus would probably emerge. Bittneria was probably an epibyssate bivalve.

  • Mineralogy.—?Bimineralic (Carter, 1990a, p. 234). There are no data for the shell of Bittneria. We cannot use the characteristic features of the family due to its doubtful systematic allocation. Nevertheless, it is likely that Bittneria had a bimineralic shell, as did most members of the Order Pectinioida.

  • Genus HOKONUIA Trechmann, 1918, p. 202

  • Type species.Hokonuia limaeformis Trechmann, 1918, p. 204.

  • Remarks.—Although Hokonuia was related to the families Pergamidiidae (Trechmann, 1918; Waterhouse, 1960), Myalinidae (Trechmann, 1918; Wilckens, 1927) and Pteriidae (Marwick, 1953), it is now referred to Buchiidae (Cox & others, 1969; H. J. Campbell, 1983; Begg & Campbell, 1985; Sha & Fürsich, 1994).

  • Stratigraphic range.—Upper Triassic (upper Carnian—Norian) (H. J. Campbell, 1983). The genus was first described from the upper Carnian (Trechmann, 1918). It was later reported from Norian beds (H. J. Campbell, 1983). According to the latest stratigraphic revision (H. J. Campbell & Raine in Cooper, 2004), the type species ranges from Oretian to Warepan (=uppermost Carnian and Norian).

  • Paleogeographic distribution.—Austral (Fig. 28). J. Chen (1982a) reported Hokonuia sp. from the Carnian of southern China, but the figured specimen (pl. II, 14) is not consistent with the diagnosis of the genus.

  • Austral domain: Late Triassic: latest Carnian—Norian of New Zealand (Trechmann, 1918; Wilckens, 1927; Marwick, 1953; Waterhouse, 1960; H. J. Campbell, 1983; Grant-Mackie, 1984).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Like the other members of the family Buchiidae, Hokonuia was an epibyssate bivalve. The byssus emerged through the deep byssal notch in the right valve (Waterhouse, 1960). Although it was suggested that some buchiids might have a pseudoplanktonic mode of life (Wignall & Simms, 1990), we do not believe Hokonuia is among them, since its distribution is very limited.

  • Mineralogy.—Bimineralic (Waterhouse, 1960; Begg & Campbell, 1985; Carter, 1990a; Carter, Barrera, & Tevesz, 1998, p. 1002). Carter, Barrera, and Tevesz (1998) indicated that the inner shell layer of Hokonuia was probably aragonitic, in contrast to other buchiids, which had three calcitic shell layers. Outer shell layer: calcite (prismatic). Middle shell layer: calcite (foliated). Inner shell layer: aragonite (homogeneous).

  • Genus SICHUANIA Chen in Gu & others, 1976, p. 151

  • Type species.Sichuania difformis Chen in Gu & others, 1976, p. 151.

  • Remarks.Sichuania Chen, 1976, was also described as a new genus in Wen and others (December 1976). Chen (in Gu & others, 1976) included Sichuania in the Buchiidae. This was followed by Sha, Chen, and Qi (1990), but, although Sichuania had the typical form of shells of the family Buchiidae, it lacked a right anterior auricle, and, for this reason, Sha and Fürsich (1994) suggested that it belongs neither to Buchiidae nor to Monotoidea. But as these authors did not propose a new assignment, Sichuania is here treated in this family, while awaiting more information.

  • Stratigraphic range.—Upper Triassic (Norian) (Chen in Gu & others, 1976). Sichuania was first described by Chen in Wen and others (1976) from the Norian of China (Sichuan and Yunnan provinces). Later, it was also reported from Rhaetian beds (Hautmann, 2001b), although without a description or the original source data. Waterhouse (1980b) provisionally attributed his supposedly Lower Triassic specimens from New Zealand to Sichuania (?Sichuania marwicki Waterhouse, 1980b). But the sediments in which he found the specimens were not of that age, and the specimens were not well accommodated in this genus (see discussion for Marwickiella, p. 79).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 28). Hautmann (2001b) mentioned Sichuania from the Norian and Rhaetian beds of Tibet and the Himalayas, but he did not indicate the source of the data. Kobayashi and Tamura (1983a) also quoted it from the Upper Triassic in several Chinese provinces and southern Tibet, but this record does not have a source of original data.

  • Tethys domain: Late Triassic: Norian of China (Chen in Gu & others, 1976; Sha, Chen, & Qi, 1990).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the translation of the original generic diagnosis provided by Waterhouse (1980b), the shell is inequivalve, with the left valve being more prominent and convex than the right, and it had a byssal sinus. Due to these characteristics, Sichuania should be regarded as an epibyssate bivalve, although Sha, Chen, and Qi (1990) only doubtfully assigned it this mode of life.

  • Mineralogy.—?Bimineralic (Carter, 1990a, p. 234). There are no data on Sichuania shell mineralogy and structure. Since its systematic position is not known, we cannot assign it the dominant mineralogy in the family. Nevertheless, it likely had a bimineralic shell, like most members of the order Pectinioida.

  • Genus MARWICKIELLA Sha & Fürsich, 1994, p. 21

  • Type species.?Sichuania marwicki Waterhouse, 1980b, p. 1.

  • Remarks.—Waterhouse (1980b) tentatively assigned his specimens to Sichuania, thinking that they belonged to the family Buchiidae. We have already seen that Sichuania is probably not a buchiid, as it lacked the typical anterior auricle. But Waterhouse's specimens have this auricle and other diagnostic features of the family Buchiidae (Begg & Campbell, 1985; Sha & Fürsich, 1994). Since seemingly this species did not fit into any Buchiidae, Begg and Campbell (1985, p. 739) argued that it represented a new genus, and later Sha and Fürsich (1994) proposed the name Marwickiella for it.

  • Stratigraphic range.—Middle Triassic (Anisian). Although Waterhouse (1980b) originally referred the beds with ?Sichuania marwicki to the Lower Triassic, Begg (1981) showed that the areas where Waterhouse collected this species were in fact of lower Anisian age.

  • Paleogeographic distribution.—Austral (Fig. 28).

  • Austral domain: Middle Triassic; Anisian of New Zealand (Waterhouse, 1980b; Begg, 1981; Begg & Campbell, 1985).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the description provided by Waterhouse (1980b) for the only species included in the genus, it was probably an epibyssate bivalve.

  • Mineralogy.—Bimineralic. According to Waterhouse (1980b), his specimens had a thin calcitic shell, although he did not perform microstructural studies of any kind. We assign the dominant mineralogy of family Buchiidae.

  • Genus ANNINGELLA Cox, 1958, p. 44

  • nom. nov. pro Anningia Cox, 1936, p. 468, non Broom, 1927, p. 227 (Amniota)

  • Type species.Anningia carixensis Cox, 1936, p. 468.

  • Remarks.—Little is known about Anningella, because it is only known from its right valve. According to Sha and Fürsich (1994), it is practically indistinguishable from Chamocardia Meek & Worthen, 1869 (a Carboniferous genus not discussed). In their opinion, this genus would be better located in the Asoellidae, but in the absence of any further study, we follow Cox and others (1969) and include it in the Buchiidae.

  • Stratigraphic range.—Lower Jurassic (Hettangian—Sinemurian) (Hallam, 1987; Warrington & Ivimey-Cook, 1990). Cox (1936) described the genus Anningia (renamed Anningella by Cox [1958]) from the Liassic of Dorset. Subsequently, Cox and others (1969) assigned it a lower Lower Jurassic range. There are some inconsistencies in the literature regarding the stratigraphic range of this genus; most authors reported it from Sinemurian beds of England (Hallam, 1976, 1977, 1987; Liu, 1995; Aberhan, 2001); however, Sepkoski (2002) assigned it a Rhaetian—Sinemurian range, allegedly taking data from Hallam (1977, 1981), but, in this last paper, the genus is not mentioned. Hallam and El Shaarawy (1982) quoted Anningella from the “Penarth group” of Rhaetian age, but later Warrington and Ivimey-Cook (1990) indicated that Anningella had its origin in the Planorbis zone (=Hettangian) of the Bristol Channel area, so we believe its presence in the Rhaetian is unlikely.

  • Paleogeographic distribution.—western Tethys (Fig. 28).

  • Tethys domain: Early Jurassic: Hettangian of England (Warrington & Ivimey-Cook, 1990); Sinemurian of England (Hallam, 1976, 1977, 1987; Liu, 1995; Aberhan, 2001).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Like the other members of the family Buchiidae, Anningella was an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 234). There are no data on the shell of Anningella. Nevertheless, it likely had a bimineralic shell, like most members of the Order Pectinioida.

  • Family MONOTIDAE Fischer, 1887 in 1880–1887
    Genus MONOTIS Bronn, 1830a, p. 284

  • Type species.Pectinites salinarius von Schlotheim, 1820, p. 230.

  • Remarks.—Although Cox and others (1969) only considered two subgenera of Monotis, M. (Monotis) and M. (Entomonotis) Marwick, 1935, p. 298, in the past three decades many more were named: Pacimonotis Grant-Mackie & Silberling, 1990; Eomonotis Grant-Mackie, 1978a, p. 102; Inflatomonotis Grant-Mackie, 1978a, p. 105; Maorimonotis Grant-Mackie, 1978a, p. 108; 1978d. Although these subgenera group species with different morphotypes and are biostratigraphically useful, they are not based on phylogenetic relationships (McRoberts, Krystyn, & Shea, 2008). However, McRoberts (2010) considered Eomonotis at genus level, following Tozer (1980). Monotis had a wide paleogeographic distribution during the Late Triassic and is a good biochronologic indicator, due to its relatively rapid morphologic change; thus, despite its limited stratigraphic range, many authors studied them from this point of view.

  • Stratigraphic range.—Upper Triassic (Norian—lower Rhaetian) (McRoberts, Krystyn, & Shea, 2008). Until very recently, Monotis was believed to be completely extinguished at the Norian—Rhaetian boundary (Wignall & others, 2007), but McRoberts, Krystyn, and Shea (2008) reported it from the lower Rhaetian.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 29). McRoberts (1997a) mentioned Monotis from the Norian of Mexico, but he neither described nor figured the material.

  • Tethys domain: Late Triassic: Norian of Slovenia (Jurkovsek, 1982a, 1982b), China (C. Chen & Yu, 1976; J. Chen & Yang, 1983), Afghanistan (Polubotko, Payevskaya, & Repin, 2001), Iran (Westermann & Seyed-Emami, 1981; Hautmann, 2001b), western Caucasus (Russia) (Ruban, 2006a), northern Alps (Austria) (Grant-Mackie & Silberling, 1990; McRoberts, Krystyn, & Shea, 2008); Rhaetian of northern Alps (Austria) (McRoberts, Krystyn, & Shea, 2008; McRoberts, 2010).

  • Circumpacific domain: Late Triassic: Norian of British Columbia (Ward & others, 2004; Wignall & others, 2007), Alaska (accreted terranes) (Grant-Mackie & Silberling, 1990; Silberling, Grant-Mackie, & Nichols, 1997), Peru (Jaworski, 1922; Steinmann, 1929; Prinz, 1985), Bolivia (Beltan & others, 1987; Suarez-Riglos & Dalenz-Farjat, 1993), Chile (Thiele, 1967; Westermann, 1970; Z. Fang & others, 1998), Nevada (United States) (Grant-Mackie & Silberling, 1990), California (McRoberts, 2010), Japan (Nakazawa, 1964; Hayami, 1975; Ando, 1983, 1984, 1986, 1987; Ando, Noda, & Sato, 1987).

  • Austral domain: Late Triassic: Norian of New Zealand (Grant-Mackie, 1976, 1978a, 1978b, 1978c, 1978d, 1980a, 1980b; H. J. Campbell, 1983; MacFarlan, 1998).

  • Boreal domain: Late Triassic: ?Carnian, Norian of Primorie (Kiparisova, 1972); Norian of northeastern Russia (Kiparisova, Bychkov, & Polubotko, 1966; Kurushin, 1990; Klets, 2006), several localities of Russia (Payevskaya, 1985), Alaska (Arctic terranes) (Silberling, Grant-Mackie, & Nichols, 1997), Arctic Archipelago (Canada) (Tozer, 1970).

  • Paleoautoecology.—B-Ps, E, S, Epi, Sed-FaM; By. Much has been speculated about the mode of life of Monotis. The interpretations range from benthic epibyssate on hard substrate (S. M. Stanley, 1972; Hallam, 1981; McRoberts, Krystyn, & Shea, 2008), byssate on aquatic plants (Ando, 1987; Hautmann, 2001b), pseudoplanktonic (Hayami, 1969a; S. M. Stanley, 1972; Silberling, Grant-Mackie, & Nichols, 1997) and even nektonic (Jefferies & Minton, 1965). These interpretations were based on the Monotis shell morphology and on the facies where different species are typically found.

  • A nektonic mode of life was proposed by Jefferies and Minton (1965) but was rejected by several authors (S. M. Stanley, 1972; Ando, 1987), since it is unlikely that Monotis could swim with its inequilateral and inequivalve shell, and some species had a byssal notch (Ando, 1987). According to S. M. Stanley (1972), a benthic mode of life for some species and a pseudoplanktonic one for others would be more in agreement with the stratigraphic and taphonomic evidence. One of the strongest arguments in favor of a pseudoplanktonic mode of life is the great paleogeographic distribution Monotis had, but this could also be explained by a long-lasting planktotrophic larval stage, which is difficult to corroborate when the protoconch is not preserved. The genus is also usually found in deep-water environments, often deficient in oxygen, but this is not always the case, since Ando (1987) reported that some Japanese species were found in shallow, well-oxygenated environments. A pseudoplanktonic mode of life is also plausible with Monotis morphology, as it had a thin shell and its anterior auricle formed a pseudoctenolium, which indicates that the shell attached to objects by its byssus (Silberling, Grant-Mackie, & Nichols, 1997). Furthermore, the preferential orientation of the shells found in the fossil record, with the concave side upward, suggests they fell floating through the water column toward the bottom, in low-turbulence environments and with little post mortem transport (Silberling, Grant-Mackie, & Nichols, 1997). However, McRoberts, Krystyn, and Shea (2008) explain this orientation by suggesting that Monotis was epibenthic and lived in this position on the bottom and in cave fissures.

  • According to criteria by Wignall and Simms (1990) to distinguish between obligate and facultative pseudoplanktonic bivalves, and taking into account everything mentioned above, Monotis could be facultative, as it is not usually associated with objects suitable for fixation. As mentioned above, it is often, but not always (see Ando, 1987), found associated with deep facies. Moreover, it is often found in low-oxygen facies, and this could have several explanations, from shells falling into these facies because they had a pseudoplanktonic mode of life, or the presence of some kind of symbiotic organisms that made living in those environments possible, although there is no evidence to support this last possibility (A. G. Fischer & Bottjer, 1995).

  • According to this evidence, we agree with S. M. Stanley (1972) and consider that some species were epibyssate on the bottom and others might have had a facultative pseudoplanktonic mode of life.

  • Mineralogy.—?Calcitic (Carter, 1990a, p. 248; Carter, Barrera, & Tevesz, 1998). According to Carter, Barrera, and Tevesz (1998), members of family Monotidae have three calcitic shell layers, although Carter (1990a) noted that the presence of a thin sublayer of aragonite in the inner or middle shell layer of one or both valves was possible. According to the emended diagnosis offered by Carter (1990a) for the family Monotidae, the shell is built of foliated calcite with a thin homogeneous layer within one or both valves.

  • Figure 29.

    Paleogeographical distribution or Monotiidae (Monotis, Otapiria). 1, Early Triassic; 2, Late Triassic—Early Jurassic.

    f29_01.jpg

    Genus OTAPIRIA Marwick, 1935, p. 302

  • Type species.—Pseudomonotis marshalli Trechmann, 1923, p. 270.

  • Remarks.—According to Begg and Campbell (1985), Damborenea (1987b, 2002a), Ando (1987), and Carter (1990a), we include Otapiria in Monotidae (see Damborenea, 1987b, p. 154, for discussion on this topic); although Cox and others (1969), like other later authors (e.g., J. Yin, H. Yao, & Sha, 2004) included it in Aviculopectinidae. We consider Lupherella Imlay, 1967, p. 8, as a subgenus of Otapiria and Pleuromysidia Ichikawa, 1954, p. 52, as a synonym of Otapiria (see discussion in Genera not Included, p. 167).

  • Stratigraphic range.—Lower Triassic (Olenekian)—Upper Jurassic (Kimmeridgian) (Dagys & Kurushin, 1985; Damborenea, 1987b). Cox and others (1969) assigned it an Upper Triassic (Rhaetian)—Upper Jurassic (Tithonian) range. Damborenea (1987b), in her exhaustive review of the species that were attributed to the genus, recorded Kimmeridgian as the youngest record, as did Sha (1996). It is thought that Otapiria originated during the Early Triassic in the Boreal domain (Dagys & Kurushin, 1985), although it was not until Carnian times that this genus began to be abundant (Ando, 1988). Dagys and Kurushin (1985) proposed a new subgenus and new species, Otapiria (Praeotapiria) bakevelliaeformis from Lower Triassic beds. According to Ando (1988), this new subgenus is unnecessary, since morphological differences with other species of Otapiria are very subtle.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 29). According to Sha (1996), Otapiria originated in the Boreal domain and probably also in the Austral, and its distribution was most likely conditioned by water temperature and substrate. It was especially recorded at high and middle latitudes and adapted to low temperatures (Damborenea, 1993). It is regarded as a bipolar (Damborenea, 1996a) or antitropical taxon (Sha, 1996). According to Sha (1996), during the Early Triassic—Late Jurassic interval, it was widely distributed in Austria, Carpathians, Alaska, northern and northeastern Siberia, Japan, New Caledonia, New Zealand, Peru, Chile, Argentina, Colombia, and Ecuador. It was only known from northeastern Siberia, New Zealand, and Chile from the Late Jurassic. Damborenea (1986) regarded this as a circumpacific genus with sporadic appearances in the Tethys, and this is corroborated by our data.

  • Tethys domain: Late Triassic: Norian of Austria (Grant-Mackie & Zapfe, 1973; Zapfe, 1973); Rhaetian of Austria (Zapfe, 1973; McRoberts, 2010); Early Jurassic; southeastern China (J. Yin, H. Yao, & Sha, 2004).

  • Circumpacific domain; Late Triassic; Carnian of Japan (Hayami, 1975; Ando, 1988); Norian of Chile (Chong & Hillebrandt, 1985; Covacevich, Pérez, & Escobar, 1991), Japan (Ando, 1988); Early Jurassic; Hettangian—Sinemurian of Chile (Escobar, 1980); Sinemurian of Canada (Poulton, 1991; Aberhan, 1998a, 1998b), Chile (Covacevich & Escobar, 1979; Aberhan, 1993, 1994a, 1998b).

  • Austral domain; Late Triassic; ? Andes (Argentina) (Covacevich, Pérez, & Escobar, 1991; Riccardi & others, 1997, 2004); Rhaetian of New Zealand (Marwick, 1953; Grant-Mackie, 1960) and Argentina (Damborenea & Manceñido, 2012); Early Jurassic; Hettangian—Sinemurian Neuquén basin (Argentina) (Damborenea, 1987b, 1993, 1996a, 2002a; Damborenea & Manceñido, 2005b), New Zealand (Marwick, 1953; Grant-Mackie, 1960), New Caledonia (Marwick, 1953).

  • Boreal domain; Early Triassic; Siberia (Dagys & Kurushin, 1985); Late Triassic; Carnian of Primorie (Kiparisova, 1972); Norian of Siberia (Okuneva, 1985, 1986); Norian—Rhaetian of Siberia (Klets, 2006); Early Jurassic; Hettangian—Sinemurian of Siberia (Polubotko, 1968b).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Ando (1988), after studying the environments and taphonomy related to Otapiria, concluded that it was probably an epibyssate bivalve. Although wood fragments were found associated with Otapiria dubia (Ichikawa, 1954), there was no evidence that the bivalve was attached to them. However, due to the shell orientation, they probably attached to each other by their byssus. Both the sediments in which Otapiria is usually found and its orientation indicate that its mode of life was different from Monotis (Ando, 1988). An epibyssate mode of life was also proposed for other species of Otapiria (Gruber, 1984).

  • Mineralogy.—?Calcitic (Carter, 1990a). No data are known on Otapiria shell microstructure. According to the emended diagnosis offered by Carter (1990a) for the family Monotidae, the shell is composed of foliated calcite with a thin homogeneous outer layer on one or both valves. Carter, Barrera, and Tevesz (1998) assigned a calcitic mineralogy to the three shell layers of family Monotidae members.

  • Family OXYTOMIDAE Ichikawa, 1958
    Genus OXYTOMA Meek, 1864, p. 39

  • Type species.—Avicula muensteri Bronn, 1830b, p. 164.

  • Stratigraphic range.—?Lower Triassic, Middle Triassic (Ladinian)—Upper Cretaceous (Maastrichtian) (Abdel-Gawad, 1986; Waller & Stanley, 2005). Cox and others (1969) assigned a Upper Triassic—Upper Cretaceous range. However, over the years, Oxytoma was repeatedly reported from Middle Triassic sediments. Waller (in Waller & Stanley, 2005, p. 38) considered that the oldest records of the genus to be Oxytoma sp. aff. O. inaequivalve Sowerby var. intermedia Emmrich, and Oxytoma sp. aff. Oxytoma mojsisovicsi Teller, from Triassic beds of Fujian province in southeastern China. They assumed a Lower Triassic age, because these species appeared to be associated with Eumorphotis. They also noted that Oxytoma scythicum (Wirth, 1936), reported from the Lower Triassic, was later assigned to Towapteria (family Bakevelliidae).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 30).

  • Tethys domain: Early Triassic:? southern China (Waller & Stanley, 2005); Late Triassic: China (J. Chen, 1982a); Norian of western Carpathians (Kollarova & Kochanová, 1973); Rhaetian of the Alps (Austria) (Tanner, Lucas, & Chapman, 2004; Tomašových, 2006a), England (Ivimey-Cook & others, 1999); Early Jurassic: Sinemurian of England, France, Spain, and Portugal (Liu, 1995), Italy (Monari, 1994), Hungary (Szente, 1996).

  • Circumpacific domain: Middle Triassic: Ladinian of Nevada (Waller & Stanley, 2005); Late Triassic: ? Chile (Moscoso & Covacevich, 1982; Damborenea, 1987b); Carnian of Japan (Hayami, 1975; Ando, 1988); Norian of Japan (Nakazawa, 1956, 1963, 1964; Hayami, 1975); Norian or Rhaetian of Chile (Chong & Hillebrandt, 1985); Rhaetian of Canada (Wignall & others, 2007); Early Jurassic: Hettangian of Nevada (United States) (Guex & others, 2003; Lucas & Tanner, 2004); Hettangian—Sinemurian of Chile (Escobar, 1980; Aberhan, 1994a), Canada (Poulton, 1991; Aberhan, 1998a, 1998b; Aberhan, Hrudka, & Poulton, 1998); Sinemurian of Japan (Hayami, 1975).

  • Austral domain: Early Jurassic: Hettangian—Sinemurian of New Zealand (Marwick, 1953).

  • Boreal domain: Middle Triassic: Ladinian of Siberia (Klets, 2006), Arctic Archipelago (Canada) (Tozer, 1961); Late Triassic: Primorie (Kiparisova, 1972); Early Jurassic: Hettangian—Sinemurian of Greenland (Liu, 1995), northeastern Russia (Milova, 1988).

  • Paleoautoecology.—B-Ps, E, S, Epi, Sed-FaM; By. Species belonging to Oxytoma had a well-developed byssal notch, suggesting that they were epibyssate bivalves. They had an elongated posterior auricle, and thus Oxytoma was compared with Pteria regarding its mode of life (Cox & others, 1969), living attached by the byssus to hydrozoa, shells, or other objects (Fürsich, 1980). According to Sha (1991), Oxytoma larvae were probably planktotrophic. However, some species, such as Oxytoma inequivalve (J. Sowerby, 1819), most likely could also have had a pseudoplanktonic mode of life, because they were found attached to Echioceras shells (Sinemurian of Dorset) (Wignall & Simms, 1990, fig. 3). The evidence suggests that O. inequivalve specimens were fixed to the ammonoids when they were alive.

  • Mineralogy.—Calcitic (Carter, 1990a, p. 249). Waller (in Waller & Stanley, 2005) suggested a probably entirely calcitic shell for their specimens of Oxytoma (Oxytoma) grantsvillensis Waller in Waller & Stanley, 2005, since there was no evidence of differential recrystallization of the inner shell layer. For the family Oxytomidae, Carter (1990a) indicated that the shells were mostly calcitic, but they could have had a very thin aragonitic middle layer of cross-lamellar microstructure; however, there is no record of this middle shell layer in Oxytoma. Outer shell layer: calci te (simple prismatic). Middle and inner shell layers: calcite (foliated).

  • Figure 30.

    Paleogeographical distribution or Oxytomidae (Oxytoma, Avicularca, Meleagrinella, Jianchuania, Palmoxytoma). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f30_01.jpg

    Genus AVICULARCA Bubnoff, 1821, p. 281

  • Type species.—Avicula cardiiformis Münster, 1841, p. 78.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Carnian). Cox and others (1969) assigned it an Upper Triassic range in the southern Alps. The type species was reported from sediments of this age (Wissman & Münster, 1841), and later, the genus was mentioned by Laube (1865) as being from the same stage. However, Bubnoff (1821) proposed Avicularca as a subgenus of Avicula, and he included three new species from the Italian Ladinian. Sepkoski (2002) assigned it a Carnian, ?Rhaetian range, following Crame (1996), but the last author did not adequately substantiate this range.

  • Paleogeographic distribution.—western Tethys (Fig. 30). Tethys domain: Middle Triassic: Ladinian of Pedrazzo (Italy) (Kutassy, 1931); Late Triassic: southern Alps (Italy) (Wissman & Münster, 1841; Laube, 1865).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the generic diagnosis offered by Cox and others (1969, p. 344), Avicularca was probably an epibyssate bivalve.

  • Mineralogy.—Unknown. There are no data about Avicularca shell mineralogy. Since the allocation of this genus by Cox and others (1969) was doubtful, we cannot assign the predominant mineralogy of family Oxytomidae.

  • Genus MELEAGRINELLA Whitfield, 1885, p. 71

  • Type species.—Avicula curta Hall, 1852, p. 412.

  • Stratigraphic range.—Upper Triassic (Norian)—Lower Cretaceous (Albian) (Tozer, 1970; Wen, 1999). Although Cox and others (1969) assigned it an Upper Triassic (Rhaetian)—Upper Jurassic range, Meleagrinella was later reported from the Lower Cretaceous: Berriasian (X. Li, 1990), Valanginian (Kaim, 2001), and Albian (Wen, 1999). There are some disagreements regarding the origin of Meleagrinella. Sepkoski (2002) recorded that it ranges from Rhaetian times, based on data provided by Crame (1996), who surely followed Cox and others (1969). Meleagrinella was quoted from the Norian of British Columbia associated with Monotis (Westermann & Verman, 1967; Wignall & others, 2007), but specimens were neither figured nor described. The same occurred in the paper by Klets (2006), who considered Meleagrinella to have originated during the Anisian in the Boreal domain. He probably based this on data in Dagys and Kurushin (1985), who included Avicula polaris Kittl, 1907, and Pseudomonotis tasaryensis Voronetz, 1936, in Meleagrinella, and quoted the Anisian of Siberia from them. Avicula polaris was also reported from Carnian beds of Norway (Diener, 1923). Nevertheless, we leave this record as questionable, since we were unable to confirm this information, as none of these authors mentioned the original records. Tozer (1970) recorded Meleagrinella antiqua Tozer from the Norian of the Arctic Archipelago, and this age will be taken provisionally as the first record of the genus.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 30). Although Meleagrinella was present from the Late Triassic, it started to be more abundant and widely distributed during the Pliensbachian (Marwick, 1953; Duff, 1975; Wen, 1982; Pugaczewska, 1986; Jaitly, 1988; X. Li & Grant-Mackie, 1994; J. Chen, 1999; Harries & Little, 1999; Damborenea, 2002a; Delvene, 2003; Fraser, Bottjer, & Fischer, 2004; Kenig & others, 2004; Fürsich & others, 2005; Fürsich & Thomsen, 2005; Zakharov & others, 2006).

  • Tethys domain; Late Triassic; Rhaetian of Austria (Hallam & El Shaarawy, 1982; Early Jurassic; Hettangian—Sinemurian of northwestern Europe (Aberhan, 2001); Sinemurian of Europe (Quenstedt, 1856–1858), England (Liu, 1995).

  • Circumpacific domain; Early Jurassic; ?Hettangian of Canada (Poulton, 1991); Sinemurian of Japan (Hayami, 1961, 1975), Canada (Poulton, 1991; Aberhan, 1998a, 1998b).

  • Boreal domain; Late Triassic; Norian of Arctic Archipelago (Canada) (Tozer, 1970); Early Jurassic; Hettangian of northeastern Russia (Sey & others, 1981; Damborenea & others, 1992); Hettangian—Sinemurian of Greenland (Liu, 1995).

  • Paleoautoecology.—B-Ps, E, S, Epi, Sed-FaM; By. The external morphology of Meleagrinella suggests an epibyssate mode of life. Duff (1975) considered that while Meleagrinella may not have been strictly benthic, it may have attached to algae or even floating objects such as wood fragments, implying a pseudoplanktonic mode of life. Duff (1975) classified it as pendent. It is often reported from bituminous shales. However, Kaim (2001) found Meleagrinella specimens associated with cemented oysters; therefore, in this case, the mode of life was not necessarily pseudoplanktonic.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 249). Outer shell layer: calcite (prismatic). Middle shell layer: aragonite (cross-lamellar, in right valve). Inner shell layer: calcite (foliated).

  • Genus JIANCHUANIA J. Chen & Chen, 1980, p. 57, 59

  • Type species.—Pteria? problematica J. Chen in Ma & others, 1976, p. 287.

  • Stratigraphic range.—Upper Triassic (?Rhaetian) (J. Chen & Chen, 1980). J. Chen and Chen (1980) proposed Jianchuania and reported it from Upper Triassic beds of Yunnan (China), but they did not specify the stage. However, in the systematic discussion of the genus, they suggested that the specimens described by Healey (1908) as Conocardium? sp. and Conocardium superstes Healey, 1908, from the Rhaetian of Burma, are very similar and appeared in coeval deposits.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 30). Jianchuania was endemic to Yunnan province, China.

  • Tethys domain; Late Triassic; ?Rhaetian of Yunnan (China) (J. Chen & Chen, 1980).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Jianchuania had a strongly inequilateral and inequivalve shell, with a deep byssal notch and an elongated posterior auricle, similar to Pteria. It was probably an epibyssate bivalve.

  • Mineralogy.—Bimineralic. There are no data about Jianchuania shell mineralogy. We therefore used data provided for the family Oxytomidae.

  • Genus PALMOXYTOMA Cox, 1962, p. 593

  • Type species.—Pecten cygnipes Young & Bird, 1822, p. 235.

  • Remarks.—Although Cox (1962) proposed Palmoxytoma as subgenus of Oxytoma and this was maintained in Cox and others (1969), we consider Palmoxytoma to be at the generic level following Damborenea (2002a).

  • Stratigraphic range.—Lower Jurassic (Hettangian—Pliensba-chian) (Cox, 1962). Cox and others (1969) assigned the genus as lower to middle Lower Jurassic range, and this is maintained here. Although there are many papers that regard its origin as Hettangian (see paleogeographic distribution below), Guex and others (2003) and Lucas and Tanner (2004) recorded Palmoxytoma from Rhaetian beds of Nevada, but they neither described nor figured the specimens. Some species such as Oxytoma mojsisovicsi Teller, 1886, Oxytoma koniensis Tuchkov, 1956, and Oxytoma gizhigensis Milova, 1976, which are transitional between Oxytoma Meek, 1864, and Palmoxytoma, were considered to be in O. (Palmoxytoma) by some authors (e.g., Milova, 1976; but see Hayami, 1975), and if they were accepted as belonging to Palmoxytoma, its range would be extended to Upper Triassic.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 30). Palmoxytoma had a bipolar distribution during the Hettangian (Damborenea, 1993; Sha, 1996; Aberhan, 1998b, 1999), and it appears to have been restricted to the Boreal domain during the Pliensbachian (Damborenea, 1993). Although it was also present in the Tethys and Circumpacific domains, it was not recorded at low paleolatitudes.

  • Tethys domain; Early Jurassic; Hettangian of England, Sweden, France, Switzerland (Cox, 1962).

  • Circumpacific domain; Early Jurassic; Hettangian of Chile (Aberhan, 1994a); Sinemurian of Canada (Poulton, 1991; Aberhan, 1998a), Japan (Hayami, 1975).

  • Austral domain; Early Jurassic; Hettangian of Argentina (Riccardi & others, 1991; Damborenea, 2002a; Damborenea & Manceñido, 2005b; Damborenea & Lanes, 2007), New Zealand (Trechmann, 1923).

  • Boreal domain; Early Jurassic; Hettangian of northeastern Siberia (Polubotko, 1968b).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. We assign a mode of life similar to Oxytoma, but there is no evidence for a pseudoplanktonic mode of life.

  • Mineralogy.—Calcitic (Carter, 1990a, p. 249; Carter, 1990b, p. 371). Carter (1990b, p. 371) indicated that the outer shell layer of the type species of Palmoxytoma was built of prismatic calcite. We assume a calcific mineralogy, as in Oxytoma, since there is no evidence of an aragonitic middle shell layer.

  • Family ASOELLIDAE Begg & Campbell, 1985

  • Begg and Campbell (1985) proposed the family Asoellidae, naming Asoella Tokuyama, 1959c, as type genus and including their new genus Etalia.

  • Genus ASOELLA Tokuyama, 1959c, p. 2

  • Type species.—Eumorphotis (Asoella) confertoradiata Tokuyama, 1959c, p. 4.

  • Remarks.—Although Cox and others (1969) included Asoella in the Aviculopectinidae following the original reference, Begg and Campbell (1985) proposed the family Asoellidae to accommodate Asoella, Etalia Begg & Campbell, 1985, p. 727, and probably also Aucellina Pompeckj, 1901, p 365. They related and characterized these three genera in having edentulous hinges and a subumbonal resilifer with anterior and posterior areas.

  • Stratigraphic range.—Middle Triassic (Anisian)—Lower Jurassic (Pliensbachian) (Sha, Chen, & Qi, 1990; Damborenea, 2002a). Cox and others (1969) assigned this genus a Norian range in Japan, since at that time only that information was available. Sepkoski (2002), based on Hayami (1975) and H. Yin (1985), assigned it an Anisian—Norian range. Regarding the origin of Asoella, it seems reasonably acknowledged that it was present in the Anisian of China (Kobayashi & Tamura, 1983b; H. Yin, 1985; Sha, Chen, & Qi, 1990; Tong & Liu, 2000) and Vietnam (Komatsu, Huyen, & Huu, 2010). Tong and Liu (2000) reported Asoella illyrica and Asoella subillyrica from the Anisian of China, but K. Huang and Opdyke (2000) suggested that the former is currently Leptochondria illyrica (Bittner) (see K. Huang & Opdyke, 2000, p. 80; Waller & Stanley, 2005, p. 35). Lu and Chen (1986) doubtfully assigned Leptochondria subparadoxica H. Yin & Yin to Asoella. As we have observed in these Chinese publications, there seems to be some confusion between Leptochondria and Asoella; Asoella records from the Middle Triassic of China should be reviewed. In addition, Waller and Stanley (2005) indicated that their Ladinian specimens from the United States, if they really belong to Asoella, would be the oldest records of this genus. In principle, since we cannot access all the information related to Asoella from China, we provisionally use Anisian as the oldest record. Although Asoella was considered to have vanished at the end of the Late Triassic in the past (Hallam, 1981, 1990), in recent years, it was reported from Sinemurian and Pliensbachian beds of South America (Damborenea, 2002a) and Hettangian—Pliensbachian beds of New Zealand (MacFarlan, 1998; N. Hudson, 2003). Its presence in New Zealand is accepted with caution, since the specimens were not described.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 31).

  • Tethys domain: Middle Triassic: Anisian of southern China (Sha, Chen, & Qi, 1990); Anisian—Ladinian of northern Vietnam (Komatsu, Huyen, & Huu, 2010); Late Triassic: Carnian of China (J. Chen, 1982a; X. Li, Meng, & Wang, 2005).

  • Circumpacific domain: Middle Triassic: Ladinian of ?Nevada (United States) (Waller & Stanley, 2005); Late Triassic: Carnian—Norian of Japan (Hayami, 1975).

  • Austral domain: Late Triassic: Argentina (Damborenea & Manceñido, 2012); Early Jurassic: Sinemurian of Argentina (Damborenea, 1996a, 2002a; Damborenea & Manceñido, 2005b; Damborenea & Lanés, 2007); Hettangian—Sinemurian of ?New Zealand (MacFarlan, 1998; N. Hudson, 2003).

  • Paleoautoecology.—B, E, S, Epi-Un, Sed; By-R. Begg and Campbell (1985, p. 727), in their diagnosis of superfamily Monotoidea, which includes Asoellidae, stated, “Byssate Pectinina with right valve against substrate and with a distinct byssal notch throughout life.” Damborenea (2002a) indicated that Asoella asapha (A. F. Leanza, 1942) was an epibyssate bivalve, at least in the juvenile stages, but it could have lived reclined on its right valve in the adult stage. Besides, since some species were consistently found in association with plant remains, it is possible that they could attach themselves to plants (Damborenea & Manceñido, 2012).

  • Mineralogy.—?Calcitic (Begg & Campbell, 1985; Carter, 1990a, p. 248). Begg and Campbell (1985) indicated that the outer shell layer was made of prismatic calcite. Carter (1990a) added that the shell was probably all foliated and calcitic, except the outer shell layer, which probably had a prismatic microstructure.

  • Figure 31.

    Paleogeographical distribution of Asoellidae (Asoella, Etalia). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f31_01.jpg

    Genus ETALIA Begg & Campbell, 1985, p. 727

  • Type species.—Etalia johnstoni Begg & Campbell, 1985, p. 727.

  • Stratigraphic range.—Middle Triassic (Anisian) (Begg & Campbell, 1985). Etalia was originally reported from the Anisian beds of New Zealand, and no other record of the genus is known. Since it had a restricted stratigraphic range (Etalian, New Zealand regional stage correlated with Anisian), it is a good index fossil for this stage (Begg & Campbell, 1985; H. J. Campbell & Raine in Cooper, 2004).

  • Paleogeographic distribution.—Austral (Fig. 31). Austral domain: Middle Triassic: Anisian of Nelson and Southland (New Zealand) (Begg & Campbell, 1985).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Begg and Campbell (1985) recorded some specimens in life position and demonstrated that they had a gregarious habit, attaching to each other by the byssus, and reclining the right valves on the substrate, leaving the left valve free to open or close the shell. Authors considered it to be an opportunistic bivalve, a rapid colonizer of shallow-water environments.

  • Mineralogy.—?Calcitic (Begg & Campbell, 1985; Carter, 1990a, p. 248). Begg and Campbell (1985) indicated that the outer shell layer of the right valves was made of prismatic calcite. Although they did not mention anything about the inner shell layers, they pointed out that the shell was thin and probably calcitic. Carter (1990a), discussing the family Asoellidae, noted that the shell is almost entirely composed of calcite and probably of foliated microstructure, but the outer shell layer of the right valve contatined prismatic calcite.

  • Family PROSPONDYLIDAE Ptchelincev, 1960

  • =Terquemiidae Cox, 1964

  • Due to the wide range of different opinions in the literature about relations of the various genera included in this family, and as it is not an objective of this paper to review all of them, we follow mainly Hautmann (2001a) in his analysis of Prospondylidae, since it seems the most appropriate.

  • Genus TERQUEMIA Tate in Woodward, 1868, p. 65

  • nom. nov. pro Carpenteria Eudes-Deslongchamps, 1860, p. 127, non Gray, 1858, p. 269

  • Type species.—Carpenteria pectiniformis Eudes-Deslongchamps, 1860, p. 130.

  • Remarks.—Most references to this genus are often based on badly preserved specimens, resulting in a poorly known genus (Damborenea, 2002a; Hautmann & Golej, 2004). The main difficulty is that several genera in this family are externally very similar, and if details of the hinge and other internal characters of the specimens cannot be observed, it is very difficult to know to which genus they belong.

  • Stratigraphic range.—Lower Jurassic (Sinemurian), ?Upper Jurassic (Hautmann & Golej, 2004). Although Cox and others (1969) assigned it an Upper Triassic—Upper Jurassic range, according to Hautmann (2001a, p. 344): “Most Triassic species assigned to Terquemia in lower publications actually belong to Newaagia or Enantiostreon. Although there are some incompletely preserved specimens which might belong to Terqumia, there is no unequivocal record from rocks older than Lower Jurassic.”

  • Ivimey-Cook and others (1999), and J. Yin and McRoberts (2006), reported Terquemia difformis (Schlotheim, 1820) from the Rhaetian of the Penarth Group (England) and from the Rhaetian—Hettangian transition layers in Tibet (China), respectively, but this species was referred to Umbrostrea by Márquez-Aliaga and others (2005), because it had an aragonitic inner shell layer (De Renzi & Márquez-Aliaga, 1980; Carter, 1990a; Carter, Barrera, & Tevesz, 1998) and ligament structure, hinge, and antimarginal ribs, typical of ostreids. J. Yin, Enay, and Wan (1999) reported it from Norian beds of the Himalayas (China), but they did not describe the material, and since we cannot be sure that it is really Terqumia, it will not be taken into account. The same occurs with most of the Triassic records of the genus. We follow Hautmann (2001a) in considering the oldest solid record to be Lower Jurassic. Regarding the youngest record accepted for Terquemia, it is hard to establish due to identification problems. Fürsich and Werner (1988) reported Terquemia from the Kimmeridgian of Portugal, but their specimens were only doubtfully assigned, as the specimens are articulated, and the hinge features, which are key to a proper allocation, cannot be seen. The same occurs with the specimens assigned by Damborenea (2002a) from the Toarcian of South America. No more records of Terquemia from the Upper Jurassic were found, apart from Fürsich and Werner (1988). Tentatively we indicate its range to be until the Upper Jurassic, following Hautmann and Golej (2004).

  • Paleogeographic distribution.—Tethys (Fig. 32). Terquemia was mentioned from the Tethys domain, but the only solid reference is in Hautmann and Golej (2004). Due to pending questions about the relationship of this genus, we cannot provide a complete distribution.

  • Tethys domain: Early Jurassic: Sinemurian of Western Carpathians (Slovakia) (Hautmann & Golej, 2004).

  • Paleoautoecology.—B, E, S, C, Sed; C. Terquemia was a cemented bivalve that attached to the substrate by its right valve, leaving the left one free. Unlike other cementing bivalves, such as Persia, Terquemia lacks byssal notch, so it should not have byssate juvenile stages. In many cases, shells of other bivalves were the substrate (Damborenea, 2002a).

  • Mineralogy.—Bimineralic (Hautmann & Golej, 2004). Hautmann and Golej (2004) described an outer shell layer subdivided into two sublayers, the outer prismatic and the inner foliated (both calcitic), in their specimens of Terquemia (Dentiterquemia) eudesdeslongchampsi Hautmann & Golej, 2004. The inner shell layer was recrystallized, but assuming that this layer microstructure was the same as in the rest of the family Prospondylidae, they believed it had a cross-lamellar microstructure (aragonitic).

  • Figure 32.

    Paleogeographical distribution of Prospondylidae (Terquemia, Newaagia, Persia, Pegmavalvula). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f02_01.jpg

    Genus NEWAAGIA Hertlein, 1952, p. 275

  • nom. nov. pro Philippiella Waagen, 1907, p. 173, non Pfeffer in von Martens & Pfeffer, 1886, p. 119

  • Type species.—Spondylus obliquus Münster, 1841, p. 74. Remarks.—Hertlein (1952) proposed the name Newaagia to replace Philippiella Waagen, 1907, as the latter name had already been used for another bivalve genus, Philippiella Martens & Pfeffer, 1886.

  • Some Triassic specimens attributed to Spondylus could better fit in Newaagia (Waller, 2006, p. 334): “So-called Spondylus from the Triassic, such as the many species described by Klipstein (1843 in 1843–1845), are spiny, multicostate bivalves cemented by their right valve and having ventrally migrating ligaments that leave a higher ligament area on the right valve than on the left. Although they superficially resemble Spondylus, those that I have examined have a pteriid-type resilium and lack hinge teeth. At least some of these are assignable to Newaagia Hertlein, 1952 …”

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Rhaetian) (Hautmann, 2001a). Cox and others (1969) assigned it an Upper Triassic (Carnian) range, and, with some doubt, they noted its presence in the Permian. Newaagia was later regarded as an exclusively Mesozoic genus (Newell & Boyd, 1970). Sepkoski (2002), following H. Yin (1985), assigned it an Anisian—Carnian range. It was reported from the Anisian (H. Yin & Yin, 1983), and subsequently, from Norian and Rhaetian beds (Hautmann, 2001a, 2001b).

  • Paleogeographic distribution.—Eastern Tethys and Boreal (Fig. 32). Newaagia was reported from the Norian of China (Sha, Chen, & Qi, 1990), but this was based on only one badly preserved specimen. In addition, it was also reported from the Norian of northeastern Asia (Polubotko & Repin, 1990), but the specimens are not figured or described, and there is no other information about the genus from that area.

  • Tethys domain: Middle Triassic: Anisian of the Dolomites (Italy) (Posenato, 2008b), Dolomites (Switzerland) (Zorn, 1971), northwestern China (Qinghai province) (H. Yin & Yin, 1983); Late Triassic: Carnian of Italy (Leonardi, 1943; Allasinaz, 1966); Norian—Rhaetian of Iran (Hautmann, 2001a, 2001b; Fürsich & Hautmann, 2005); Rhaetian (transitional layers of Rhaetian—Hettangian) of Tibet (China) (J. Yin & McRoberts, 2006).

  • Boreal domain: Late Triassic: Carnian of Primorie (Kiparisova, 1972).

  • Paleoautoecology.—B, E, S, C, Sed; C. Newaagia was a cemented bivalve, attaching to hard substrates or to other shells by the umbonal area of the right valve (Newell & Boyd, 1970). It was a bioherm builder, according to Hautmann (2001b).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 251; Hautmann, 2001a). Outer shell layer: calcite (fibrous prismatic—foliated). Middle shell layer: aragonite (cross-lamellar—complex cross-lamellar). Inner shell layer: aragonite (simple prismatic).

  • Genus PERSIA Repin, 1996, p. 4 [365 in translation]

  • Type species.—Persia monstrosa Repin, 1996, p. 4 [365 in translation] .

  • Remarks.—Although Persia had some external resemblance to Newaagia and Terquemia, it is distinguishable from both by differences in the auricles, ligament area, and ornamentation (see Repin, 1996, p. 365). Persia was emended by Hautmann (2001a). Although it was originally monospecific, subsequently J. Yin and McRoberts (2006) described a new species: P. hallami J. Yin & McRoberts, 2006.

  • Stratigraphic range.—Upper Triassic (Norian)—Lower Jurassic (lower Hettangian) (Repin, 1996; J. Yin & McRoberts, 2006). The genus was originally reported from the Norian of Iran (Repin, 1996), containing only the type species. Subsequently, it was found in Rhaetian beds of the same area (Hautmann, 2001a, 2001b) and in the Rhaetian—Hettangian transitional layers of Tibet (China) (J. Yin & McRoberts, 2006).

  • Paleogeographic distribution.—Tethys (Fig. 32). Tethys domain: Late Triassic: Norian of Central Iran (Repin, 1996; Hautmann, 2001a, 2001b); Rhaetian of central Iran (Hautmann, 2001a, 2001b), Tibet (China) (J. Yin & McRoberts, 2006); Early Jurassic: early Hettangian of Tibet (China) (Tibeticum zone in J. Yin & others, 2007) (J. Yin & McRoberts, 2006).

  • Paleoautoecology.—B, E, S, C, Sed; C. The presence of a byssal notch between the anterior auricle and the disk may indicate that Persia had a byssate state before becoming cemented (Hautmann, 2001a). Persia was one of the reef-builder bivalves from the Late Triassic (Fürsich & Hautmann, 2005).

  • Mineralogy.—Bimineralic. Details of Persia shell microstructure are unknown. Probably it had a bimineralic shell, as do other members of family Prospondylidae.

  • Genus PEGMAVALVULA Newell & Boyd, 1970, p. 263

  • Type species.—Pegmavalvula gloveri Newell & Boyd, 1970, p. 263.

  • Stratigraphic range.—lower Permian (Artinskian)—Lower Triassic (Olenekian) (Newell & Boyd, 1970, 1995). Although, according to Hautmann (2001a), Pegmavalvula was a Paleozoic genus, there is evidence that at least one species, P. triassica Newell & Boyd, 1995, was present in the Lower Triassic (Newell & Boyd, 1995).

  • Paleogeographic distribution.—Circumpacific (Fig. 32). Pegmavalvula was reported from Guadalupian to Artinskian levels of North America (Newell & Boyd, 1970); it was also reported from Greece in Changhsingian beds (Clapham & Bottjer, 2007), although these authors did not figure or describe the specimens.

  • Circumpacific domain: Early Triassic: Olenekian of Nevada (United States) (Newell & Boyd, 1995).

  • Paleoautoecology.—B, E, S, C, Sed; C. Species belonging to Pegmavalvula were cemented to the substrate with almost the entire surface of the right valve (Newell & Boyd, 1995). Shells had a byssal notch in juvenile stages, but this was closed in the adult stage. This fact was interpreted as evidence that they had an early byssate phase (pectiniform stage) before cementing to the substrate (Newell & Boyd, 1970).

  • Mineralogy.—Bimineralic. Pegmavalvula shell mineralogy is not known. It was probably bimineralic, as were other members of family Prospondylidae.

  • Figure 33.

    Paleogeographical distribution of Pergamidiidae (Pergamidia, Krumbeckiella, Manticula, Semuridia, Parapergamidia, Oretia). Late Triassic—Early Jurassic.

    f33_01.jpg

    Family PERGAMIDIIDAE Cox in Cox & others, 1969
    Genus PERGAMIDIA Bittner, 1891, p. 103

  • Type species.—Pergamidia eumenea Bittner, 1891, p. 103. Stratigraphic range.—Upper Triassic (Norian) (L. Lin & others, 2007). Cox and others (1969) assigned it a Norian range, which is confirmed by the reviewed literature. However, Sha and others (2005) indicated that Pergamidia lived from Carnian to Norian, but later, in another paper (L. Lin & others, 2007), Pergamidia was assigned an exclusively Norian genus.

  • Paleogeographic distribution.—Tethys (Fig. 33). Pergamidia was widely distributed throughout the Paleotethys suture, extending from the Carpathians to the Java Sea (Sha & others, 2005).

  • Tethys domain: Late Triassic: Norian of Turkey (Bittner, 1891, 1892), Timor (Indonesia) (Krumbeck, 1924), Yunnan province (China) (Cowper-Reed, 1927; Sha & others, 2005), Lungma region (China) (Wen & others, 1976), Qinghai province (China) (Sha, Chen, & Qi, 1990).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Pergamidia had a mytiliform shell and was monomyarian; it also had a very deep byssal notch, suggesting that it possessed a large byssus to attach itself to the substrate (Sha & others, 2005). Due to the associated substrate type, its low diversity, and high abundance, it was probably able to put up with extreme conditions, even toxic environments (sulphuric) and those low in oxygen. They were found in large numbers in rift zones and island arcs, which were more or less affected by tectonic movements and volcanic activity. These types of environments imply shallow to deep waters and toxic sulfide seas (Sha & others, 2005). Pergamidia was considered an opportunist taxon capable of colonizing highly stressed environments where other organisms could not live, with very unstable populations that went extinct rapidly (Sha & Fürsich, 1994).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 196). There are no data about Pergamidia shell mineralogy. We assume a bimineralic shell, as in the other members of the order Pterioida.

  • Genus KRUMBECKIELLA Ichikawa, 1958, p. 196

  • nom. nov. pro Timoria Krumbeck, 1924, p. 218, non Kaye, 1919, p. 93

  • Type species.—Timoria timorensis Krumbeck, 1924, p. 221. Remarks.—Krumbeck (1924) proposed the genus Timoria, being unaware that this name was already in use for an insect genus, Timoria Kaye, 1919. Ichikawa (1958) realized this and renamed the genus as Krumbeckiella.

  • Stratigraphic range.—Upper Triassic (Carnian—upper Rhaetian) (Sha, Chen, & Qi, 1990; J. Yin & McRoberts, 2006). The type species of Krumbeckiella was described by Krumbeck (1924) from the Norian of Timor, and this was the stratigraphic range assigned by Cox and others (1969). Subsequently, Krumbeckiella was also reported from upper Rhaetian beds (J. Yin & McRoberts, 2006). Sha, Chen, and Qi (1990) reported the genus from the Carnian, and it seems to be fairly common in sediments of that age (X. Wang & others, 2008).

  • Paleogeographic distribution.—Tethys (Fig. 33). Although the species Krumbeckiella cf. timorensis (Krumbeck, 1924) was mentioned from the Circumpacific domain by Newton (in Newton & others, 1987), Waller (in Waller & Stanley, 2005) showed that specimens described by Newton (in Newton & others, 1987) actually belong to Mysidiella Cox, 1964, and he renamed the species Mysidiella newtonae Waller in Waller & Stanley, 2005. In addition, Waller and Stanley (2005) reported the presence of Krumbeckiella at high paleolatitudes in the southern hemisphere, but we did not locate in the literature any reference of the genus from that area.

  • Tethys domain: Late Triassic: Carnian of Qinghai province (China) (Sha, Chen, & Qi, 1990); Norian of Timor (Indonesia) (Krumbeck, 1924), China (Wen & others, 1976), Tibet (China) (Kobayashi & Tamura, 1983a), Qinghai province (China) (Sha, Chen, & Qi, 1990); Rhaetian of Tibet (China) (J. Yin & McRoberts, 2006; J. Yin & others, 2007).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The mode of life of Krumbeckiella was probably similar to that of Pergamidia.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 196). Krumbeckiella shell mineralogy is unknown. As for other members of Pterioida, it could have had a bimineralic shell.

  • Genus MANTICULA Waterhouse, 1960, p. 428

  • Type species.—Mytilus problematicus Zittel, 1864, p. 28.

  • Remarks.—Although the type species was related to Mytilus Linnaeus, 1758, and Myalina de Koninck, 1842 in 1841–1844, Waterhouse (1960) proposed the new genus Manticula, characterized by hinge details and shell microstructure. He did not provide a systematic allocation, but Cox and others (1969) referred it to the Pergamidiidae.

  • Stratigraphic range.—Upper Triassic (?Carnian—Norian), Lower Cretaceous (Berriasian) (Waterhouse, 1960; Crame, 1995). It was originally reported from the Otamitan (then regarded as Carnian) of New Zealand, and this was the stratigraphic range assigned by Cox and others (1969); subsequently, it was also reported from the Norian stage (Freneix & Avias, 1977), and now the Otamitan is correlated with the Norian (H. J. Campbell & Raine in Cooper, 2004). Crame (1995) reported it from the Early Cretaceous (Berriasian) of Antarctica and regarded Manticula as a Lazarus taxon, without Jurassic representatives, which survived in Antarctica that acted as a refuge.

  • Paleogeographic distribution.—Austral (Fig. 38). Austral domain: Late Triassic: ?Carnian, Norian of New Zealand and New Caledonia (Wilckens, 1927; Waterhouse, 1960; Freneix & Avias, 1977; W. Zhang & Grant-Mackie, 2001).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Most probably, Manticula was an epibyssate bivalve, as were the other members of the Pergamiidae; this is indicated by its mytiliform shell and the presence of byssal notch.

  • Mineralogy.—Bimineralic (Waterhouse, 1960; Carter, 1990a, p. 204). Outer shell layer: calcite (prismatic-homogeneous). Inner shell layer: aragonite (cross-lamellar).

  • Genus SEMURIDIA Melville, 1956, p. 116

  • Type species.—Semuridia jacksoni Melville, 1956, p. 116.

  • Remarks.—Semuridia was referred to the Pergamidiidae by Cox and others (1969); Waller and Stanley (2005) believed that it may be included in another clade due to differences in shell microstructure and ligament area, together with other genera of the family such as Pergamidia, Krumbeckiella, and Manticula. Carter (1990a) already indicated that if the inner shell layer of Semuridia is really nacreous, as stated by Cox and others (1969), it should be separated from the group at a subfamily or even family level.

  • Stratigraphic range.—Lower Jurassic (Sinemurian) (Cox & others, 1969). Semuridia was only recorded from Sinemurian beds (Cox & others, 1969; Hallam, 1976, 1977, 1987; Liu, 1995).

  • Paleogeographic distribution.—western Tethys (Fig. 33). Tethys domain: Early Jurassic: Sinemurian of England (Cox & others, 1969; Liu, 1995).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Like the rest of the Pergamidiidae, Semuridia is externally mytiliform, it had a byssal notch, and was monomyarian, so it is interpreted to be an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Cox & others, 1969, p. 314; Waller & Stanley, 2005). According to Cox and others (1969), Semuridia inner shell layer was nacreous (aragonite). Waller and Stanley (2005, p. 9) stated, “its outer shell layer, although not described, appears to be columnar prismatic based on figures of the left valve of Semuridia dorsetensis (Cox, 1926) in Cox [and others] (1969, fig. C44.4a).”

  • Genus PARAPERGAMIDIA L. Lin & others, 2007, p. 110

  • Type species.—Parapergamidia changtaiensis L. Lin & others, 2007, p. 111.

  • Stratigraphic range.—Upper Triassic (?upper Carnian—lower Norian) (L. Lin & others, 2007). Parapergamidia occurs in the Norian and probably also in the upper Carnian (L. Lin & others, 2007).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 33).

  • Tethys domain: Late Triassic: late Carnian—early Norian of western Sichuan (southwestern China) (L. Lin & others, 2007).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Externally similar to Pergamidia, the main differences are based on the shape of the retractor muscles and the thickness of the shell (L. Lin & others, 2007). The byssal retractor muscle scars of Parapergamidia are very prominent and indicate it was fixed by the byssus. It had the same external mytiliform appearance as other members of the family to which it belongs. Its mode of life was probably similar to Pergamidia. Interpretation of the facies in which it occurs shows that it lived in deep-water environments (L. Lin & others, 2007). Mineralogy.—Bimineralic (Carter, 1990a, p. 196). Parapergamidia shell microstructure is unknown. Bimineralic mineralogy is assumed as in the other members of the order Pterioida.

  • Genus ORETIA Marwick, 1953, p. 62

  • Type species.—Oretia coxi Marwick, 1953, p. 62.

  • Remarks.—Marwick (1953) included Oretia in the family Pteriidae, but later Cox and others (1969) attributed it to an uncertain family within the superfamily Pectinoidea. Waterhouse (1979a) emended the generic diagnosis, and he tentatively included it in Pergamidiidae, but he also found some similarities with Monotiidae and Mysidiellidae.

  • Stratigraphic range.—Upper Triassic (lower Norian) (Marwick, 1953; H. J. Campbell & Raine in Cooper, 2004). The genus is restricted to the Oretian (New Zealand local stage), and halobiid and ammonoid correlations suggest a lowest Norian age (H. J. Campbell & Grant-Mackie, 2000); the stage was correlated with lower Norian (H. J. Campbell & Raine in Cooper, 2004).

  • Paleogeographic distribution.—Austral (Fig. 33). Tethys domain; Late Triassic; early Norian of New Zealand (Marwick, 1953; Waterhouse, 1979a).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Probably epibyssate.

  • Mineralogy.—Unknown. Oretia shell microstructure is unknown. Since its allocation to the family Pergamidiidae is uncertain, we cannot assign the dominant mineralogy in the family.

  • Superfamily HALOBIOIDEA Kittl, 1912
    Family HALOBIIDAE Kittl, 1912

  • Over the past three decades, a large number of genera and subgenera related to Daonella and Halobia were proposed (e.g., Polubotko, Payevskaya, & Repin, 2001; Kurushin & Truschelev, 2001). Some authors specializing in this group do not agree (see McRoberts, 1993, 2000, and H. J. Campbell, 1994) which criteria used to characterize these taxa are diagnostic features. The new taxa not taken into account in this paper are: Perihalobia Gruber, 1976; Zittelihalobia Polubotko, 1984; Indigirohalobia Polubotko, 1984; Parahalobia Yin & Hsu, 1938, in C. Chen, 1976; Pacifihalobia Polubotko, 1990; Primahalobia Polubotko, 1988; Comatahalobia Polubotko in Polubotko, Payevskaya, & Repin, 2001; Magnolobia Kurushin & Truschelev, 2001 (see discussion for each of them in Genera not Included, p. 156). McRoberts (1993, p. 201–202) considered Perihalobia, Indigirohalobia, Zittelihalobia, Parahalobia, and Pacifihalobia to be synonyms of Halobia. In his own words: “the characters employed to construct these new taxa are inconsistent with the included taxa, are too narrowly defined to accommodate reasonable amounts of variation, or were erected to fit an a priori assumption of inferred phylogenetic relations. Many of the characters used to define the above genera are probably best used in specific rank.” When Polubotko (1984) proposed the new genera, he emphasized the features related to the shape and size of the auricles and the type of ornamentation, characters used previously as diagnostic at the species level. In addition, there are a number of Daonella subgenera that were taken into account by Sepkoski (2002), which will not be considered here either: Dipleurites Kittl, 1912; Moussonella Turculet, 1972; Grabella Turculet, 1972; Arzelella Turculet, 1972; Loemmelella Turculet, 1972; Pichlerella Turculet, 1972; and Longidaonella Farsan, 1972; Sepkoski (2002) based these data on H. Yin (1985). Pichlerella and Arzelella are here regarded as sub genera of Daonella (Schatz, 2001b, 2004).

  • Halobia and Daonella were traditionally distinguished by the presence or absence of an anterior auricle, but in the publication of papers by Gruber (1976) and Polubotko (1984, 1988, 1990), there is no consensus about which characters are best suited to distinguish at subgeneric and generic levels (H. J. Campbell, 1994). A thorough review of the group is badly needed to establish the criteria for generic, subgeneric, and specific level discrimination, in order to restore stability, which this group had until the 1970s. In our opinion, the diverse senses in which members of the group were used, depended in part on the taxon concept of different authors. Sometimes, depending on the use to be given to the different taxa proposed, the list tends to swell as a matter of convenience, for example, in biostratigraphy. We believe that new taxa should be defined as biological concepts, as far as possible.

  • We include Daonella Mojsisovics, 1874; Aparimella H. J. Campbell, 1994; Halobia Bronn, 1830a; and Enteropleura Kittl, 1912, in this family, following H. J. Campbell (1994), McRoberts (2000), and Waller and Stanley (2005). According to McRoberts (2000, p. 600), the first three are distinguished; “Daonella lacks an anterior auricle, Aparimella possesses an upper anterior auricle, and Halobia has a two-fold anterior auricle” (byssal tube of H. J. Campbell, 1994). Daonella is similar to Enteropleura, but its ornamentation is less marked, and the ligament is alivincular, very similar to Bositra De Gregorio, 1886 (Waller & Stanley, 2005).

  • One of the difficulties with this group is that the shell is very thin and the specimens are often found with the dorsal part broken, so that unless they are very well preserved, the ligament area cannot be observed. Many of the references in the literature were based on shell fragments or on internal and external molds only, and hence the confusion between genera is common.

  • The great abundance and distribution of halobiids during the Triassic and their high speciation rate made their species very useful as biochronological indicators, which is not common among bivalves.

  • Genus HALOBIA Bronn, 1830a, p. 282

  • Type species.—Halobia salinarum Bronn, 1830a, p. 282. Stratigraphic range.—Upper Triassic (lower Carnian—middle Norian) (McRoberts, 1993, 2000). Although Cox and others (1969) assigned to Halobia a Middle—Upper Triassic range, according to McRoberts (2000, p. 602), Halobia did not appear until the early Carnian, because, “Earlier reports of Ladinian Halobia have now been determined to be either species belonging to other taxa such as Daonella and Aparimella (e.g., Campbell, 1994), or assigned to younger strata … .”

  • Paleogeographic distribution.—Cosmopolitan (Fig. 34). Although Halobia was considered to be a taxon with cosmopolitan distribution, according to McRoberts (1997b), it is not known in South America. However, Pérez-Barría (2004, 2006) reported Halobia from the Upper Triassic of Chile, but no systematic treatment of the specimens was made.

  • Tethys domain; Late Triassic; China (Cowper-Reed, 1927; Gou, 1993), Timor and Sumatra (Indonesia) (Krumbeck, 1914, 1924; Gruber in Kristan-Tollman, Barkham, & Gruber, 1987); Carnian of Tibet (China) (Sha, Johnson, & Fürsich, 2004), Qinghai province (China) (Sha, Chen, & Qi, 1990; Sha, 1995, 1998; Sha & Grant-Mackie, 1996), Xizang province (China) (C. Chen, 1982), Yugoslavia (Jurkovsek & Kolar-Jurkovsek, 1986), Italy (Leonardi, 1943; Nicora & others, 2007; McRoberts, 2010); Carnian—Norian of Slovakia (Kochanová, 1987), Sicilia (Italy) (Cafiero & Capoa de Bonardi, 1982; see records for European distribution), Apennines (Italy) (Capoa de Bonardi, 1970), Yugoslavia (Cafiero & Capoa de Bonardi, 1980), China (Wen & others, 1976), ?Singapore (Kobayashi & Tamura, 1968a), Turkey (Allasinaz, Gutnic, & Poisson, 1974); Norian of Tibet (China) (Sha, Johnson, & Fürsich, 2004), Qinghai province (China) (Sha, Chen, & Qi, 1990; Sha, 1995, 1998; Sha & Grant-Mackie, 1996), southern Russia (Okuneva, 1985, 1987), Austria (McRoberts, 2010).

  • Circumpacific domain: Late Triassic: early Carnian of British Columbia (Canada) (McRoberts, 2000), Japan (Ando, 1988); Carnian—Norian from various localities in North America (J. P. Smith, 1927; McRoberts, 1993, 1997b), Mexico (Lucas & González-León, 1994), Japan (Kobayashi & Ichikawa, 1949a; Nakazawa, 1964; Hayami, 1975; Tamura & others, 1975; Tanaka, 1989); Norian of British Columbia (McRoberts, 2010).

  • Austral domain: Late Triassic: ?Carnian, Norian of New Zealand and New Caledonia (Trechmann, 1918; Wilckens, 1927; Marwick, 1953; Grant-Mackie, 1960; H. J. Campbell, 1982, 1994).

  • Boreal domain: Late Triassic: Carnian of Svalbard (H. J. Campbell, 1994), Arctic Canada (McRoberts, 2010), Primorie (Kiparisova, 1972); Carnian—Norian of Arctic zone of Canada (Tozer, 1961, 1962; McRoberts, 1997b), Siberia (McRoberts, 1997b and references therein); Norian of Svalbard (H. J. Campbell, 1994).

  • Paleoautoecology.—B-Ps, E, S-Ch, Epi-Un, Sed-FaM; By-R. Many authors have speculated about mode of life of halobiids; Jefferies and Minton (1965), Hayami (1969a), S. M. Stanley (1972), Seilacher (1990), H. J. Campbell (1994), Etter (1996), McRoberts (1997b), Waller (in Waller & Stanley, 2005), and Schatz (2005), among many others.

  • To explain their wide distribution, association with low oxygen facies, morphology, and population structure, different modes of life were postulated: benthic semi-infaunal, benthic epifaunal on the substrate associated with chemosynthetic bacteria, epibyssate on plants or seaweed, pseudoplanktonic fixed to floating objects or other living organisms (such as ammonoids), nektonic (see Schatz, 2005). There are arguments for and against almost all suggested modes of life (good reviews of this topic are in H. J. Campbell, 1994, and Schatz, 2005).

  • Possibly several modes of life can be assigned to the species of this group (H. J. Campbell, 1994), although Schatz (2005) supported an epibenthic pleurothetic mode of life on soft substrate and adapted to low oxygen environments for daonellids, as the thin shell could have facilitated the oxygen exchange in these extreme environments. However, other authors, such as McRoberts (1997b) and H. J. Campbell (1994), suggested that a pseudoplanktonic mode of life cannot be ruled out, although Schatz (2005) argued that the morphology exhibited by daonellids and other evidence does not support this hypothesis. The wide distribution of these bivalves may be due to long-term planktotrophic larvae (H. J. Campbell, 1994; McRoberts, 1997b, 2000; Sha, 2003). The external morphology of some species could fit into a swimming mode of life (subcircular form, equivalve, and short hinge line), but the adductor muscle scar is small and falls just below the umbo, and the shells are too thin (Schatz, 2005). The discussion is far from settled, and it is possible that the different morphologies of members of the group indicate slightly different modes of life.

  • Mineralogy.—Bimineralic (H. J. Campbell, 1994). Outer shell layer: calcite (prismatic). Middle shell layer: aragonite (homogeneous). Inner shell layer: calcite (foliated or lamellar).

  • Figure 34.

    Paleogeographical distribution of Halobiidae (Halobia, Daonella, Enteropleura, Aparimella). 1, Middle Triassic; 2, Late Triassic.

    f34_01.jpg

    Genus DAONELLA Mojsisovics, 1874, p. 7

  • Type species.—Halobia lommeli Wissmann in Wissmann & Münster, 1841, p. 22.

  • Stratigraphic range.—Middle Triassic (Anisian—Ladinian). Cox and others (1969) assigned Daonella a Triassic range. The range is currently limited to the Middle Triassic. Daonella pichleri Mojsisovics, 1874, was mentioned also from the Carnian by Cafiero and Capoa de Bonardi (1980), but Schatz (2001b) reviewed this species and included it within the subgenus Pichlerella, and he limited its range to the archelaus zone (upper Ladinian). McRoberts (2010) mentioned that several occurrences of Daonella from lower Carnian beds are known, but they remain poorly documented.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 34).

  • Tethys domain; Middle Triassic; China (Cowper-Reed, 1927; Lu & Chen, 1986); Anisian of southern China (Komatsu, Chen, & others, 2004), Malaysia (Vu Khuc & Huyen, 1998), Slovakia (Kochanová, 1985), Germany (Bartholomä, 1983), Switzerland (Zorn, 1971); Anisian-Ladinian of Italy (Pinna & Teruzzi, 1991; Brack & Richer, 1993), southern China (J. Chen & others, 1992), Switzerland (Richer, 1968, 1969); Ladinian of Spain (Schmidt, 1935; Llopis Liadó, 1952; Vía & Villalta, 1975; Vía, Villalta, & Esteban, 1977; Márquez-Aliaga, 1983, 1985; Budurov & others, 1991; Márquez-Aliaga & Martínez, 1996; Márquez-Aliaga & others, 2002, 2004; Márquez-Aliaga & Ros, 2002, 2003), southern Alps (Switzerland) (Schatz, 2001a), Italy (Kittl, 1912; Scandone & Capoa de Bonardi, 1966; Capoa de Bonardi, 1970; Schatz, 2001b), Bosnia, Romania, Turkey, India, Vietnam (Schatz, 2001b, and references therein), Timor (Indonesia) (Krumbeck, 1924), Malaysia (Vu Khuc & Huyen, 1998), Bulgaria (Budurov & others, 1991), southern Russia (Okuneva, 1985), Slovenia (Jurkovsek, 1983, 1984), Yugoslavia (Ramovs & Jurkovsek, 1983a, 1983b; Jurkovsek, 1983), China (Wen & others, 1976), Slovakia (Kochanová, Mello, & Siblík, 1975), Bulgaria (Stefanov, 1963), Timor (Indonesia) (Krumbeck, 1924), Afghanistan (Farsan, 1972, and references therein).

  • Circumpacific domain; Middle Triassic; Anisian of Japan (Nakazawa, 1961), Nevada (United States) (McRoberts, 2010); Ladinian of Japan (Hayami, 1975; Tamura & others, 1975).

  • Austral domain; Middle Triassic; Anisian of New Zealand and New Caledonia (H. J. Campbell, 1994).

  • Boreal domain; Middle Triassic; Anisian of Svalbard (H. J. Campbell, 1994); Anisian—Ladinian of Arctic Archipelago (Canada) (Tozer, 1961, 1962, 1970); Ladinian of northeastern Asia (Kurushin & Truschelev, 2001), Svalbard (H. J. Campbell, 1994; McRoberts, 2010), British Columbia (McRoberts, 2010).

  • Paleoautoecology.—B-Ps, E, S-Ch, Epi-Un, Sed-FaM; By-R. See Halobia (p. 91).

  • Mineralogy.—Bimineralic (H. J. Campbell, 1994). Outer shell layer: calcite (prismatic). Middle shell layer: aragonite (homogeneous). Inner shell layer: calcite (foliated or lamellar).

  • Genus ENTEROPLEURA Kittl, 1912, p. 162

  • Type species.—Daonella guembeli Mojsisovics, 1874, p. 8.

  • Remarks.—The systematic position of Enteropleura varied throughout its history, from a synonym of Daonella (Krumbeck, 1924) to a subgenus of Daonella (Capoa de Bonardi, 1970) or valid genus as interpreted by Cox and others (1969) and here. Although the genus was not widely understood, and somewhat neglected, several recent studies (Hopkin & McRoberts, 2005; Waller & Stanley, 2005; J. Chen & Stiller, 2007) clarified its position. Following these papers, the species of the genus are: E. guembeli Mojsisovics, 1874; E. bittneri Kittl, 1912; E. lamellosa (Kittl, 1912); E. jenksi Hopkin & McRoberts, 2005; E. walleri Chen & Stiller, 2007. The species boeckhi Mojsisovics, 1874 (quoted as Daonella (Enteropleura) boeckhi by Capoa de Bonardi, 1970) is regarded as a Daonella (J. Chen & Stiller, 2007). Enteropleura sp. A Waller in Waller & Stanley, 2005, is the same as Enteropleura jenksi Hopkin & McRoberts, 2005.

  • Stratigraphic range.—Middle Triassic (middle Anisian) (Waller & Stanley, 2005). According to the species included in the genus, its stratigraphic range is middle Anisian and not Anisian—Norian, as assigned by Cox and others (1969). Broglio-Loriga and others (1999) reported Enteropleura from the Carnian of the Dolomites (Italy), but this will not be taken into account, because the figured specimen lacks the dorsal part, critical to establish proper relations.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 34). Tethys domain; Middle Triassic; middle Anisian of Guangxi province (southern China) (J. Chen & Stiller, 2007), Hungary (Kittl, 1912).

  • Circumpacific domain; Middle Triassic; middle Anisian of Nevada (United States) (Hopkin & McRoberts, 2005; Waller & Stanley, 2005).

  • Paleoautoecology.—B-Ps, E, S-Ch, Epi-Un, Sed-FaM; By-R. See Halobia (p. 91).

  • Mineralogy.—Bimineralic (Waller & Stanley, 2005, p. 23–24). According to Waller and Stanley (2005), their specimens of E. jenksi provided the following information; Outer shell layer: calcite (prismatic). Middle shell layer: aragonite (?). Inner shell layer: calcite (?).

  • Figure 35.

    Paleogeographical distribution or Propeamussiidae (Kolymonectes, Parvamussium). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f35_01.jpg

    Genus APARIMELLA H. J. Campbell, 1994, p. 65

  • Type species.—Daonella apteryx Marwick, 1953, p. 53.

  • Stratigraphic range.—Middle Triassic (upper Anisian)—Upper Triassic (lower Carnian) (H. J. Campbell, 1994). The stratigraphic range of Aparimella extends from Anisian to Carnian (H. J. Campbell, 1994).

  • Paleogeographic distribution.—Eastern Tethys, Austral, and Boreal (Fig. 34).

  • Tethys domain; Late Triassic: early Carnian of Yunnan (southern China) (J. Chen, 1982c).

  • Austral domain: Middle Triassic: late Anisian of New Zealand (H. J. Campbell, 1994); late Ladinian of New Zealand (Marwick, 1953; H. J. Campbell, 1994).

  • Boreal domain: Late Triassic: early Carnian of Svalbard (H. J. Campbell, 1994).

  • Paleoautoecology.—B-Ps, E, S-Ch, Epi-Un, Sed-FaM; By-R. See Halobia (p. 91).

  • Mineralogy.—Bimineralic (H. J. Campbell, 1994, p. 55). There are no specific data for Aparimella shell microstructure. We assign the data provided by H. J. Campbell (1994) for the family Halobiidae. Outer shell layer: calcite (prismatic). Middle shell layer: aragonite (homogeneous). Inner shell layer: cal cite (foliated or lamellar).

  • Superfamily PECTINOIDEA Wilkes, 1810
    Family PROPEAMUSSIIDAE Abbot, 1954
    Genus KOLYMONECTES Milova & Polubotko in Bychkov & others, 1976, p. 67

  • Type species.—Aequipecten (?) anjuensis Milova, 1969, p. 182.

  • Remarks.—Milova and Polubotko proposed Kolymonectes as a new genus in two almost simultaneous papers (in Bychkov & others, 1976, July 26; and in Milova, 1976, August 28).

  • Although Kolymonectes was regarded a member of the family Entoliidae by some authors (e.g., Polubotko & Milova, 1986), we include it in the family Propeamussiidae, following Damborenea (1998, 2002a), on the basis of the lack of ctenolium and the presence of calcite in the prismatic outer layer of the shell, two diagnostic characters of this family (Damborenea, 1998). This same approach was followed by Aberhan (1998a). However, Waller (2006) included it in the family Entolioididae Waller, 2006. Kolymonectes is regarded as a member of a propeamusiid group without internal ribs (Damborenea, 1998).

  • Stratigraphic range.—Upper Triassic (?Norian)—Lower Jurassic (lower Toarcian) (Damborenea, 2002a). Kolymonectes appeared in the upper Norian of the Boreal domain (Milova & Polubotko in Milova, 1976); Kurushin (1990) and Polubotko and Repin (1990) recorded Kolymonectes from the upper Norian (=?Rhaetian) and Hettangian. Aberhan (1998a) believed that the genus was present until the Middle Jurassic, but he did not indicate the source of this information. The youngest checked records of the genus are upper Pliensbachian (Damborenea, 2002a, 2002b) and lower Toarcian (e.g., Damborenea & others, 1992). Zakharov and others (2006) considered the record to be the lower Toarcian of northern Siberia and the Arctic area, but they did not figure or describe any specimen from than age.

  • Paleogeographic distribution.—Circumpacific, Austral, and Boreal (Fig. 35). Kolymonectes was distributed in the Boreal domain during the Late Triassic and exhibited a bipolar distribution during the Early Jurassic (Damborenea, 1993, 1996a, 1998, 2001), and although it was also reported from the Circumpacific domain, these records are located at high paleolatitudes.

  • Boreal domain; Late Triassic; northeastern Russia (Damborenea, 1998); Norian of northeastern Asia (Kurushin, 1990; Polubotko & Repin, 1990); late Norian—Rhaetian of Siberia (Milova & Polubotko in Milova, 1976); Early Jurassic; Hettangian—Sinemurian of northeastern Russia (Milova, 1988); ?Hettangian, Sinemurian of Magadan (Russia) (Polubotko & Milova, 1986), Arctic zone of Canada (Aberhan, Hrudka, & Poulton, 1998); Sinemurian of northern Russia (Milova & Polubotko in Milova, 1976).

  • Circumpacific domain; Early Jurassic; Sinemurian of western Canada (Aberhan, 1998a, 1998b).

  • Austral domain; Early Jurassic; Hettangian—Sinemurian of Argentina (Damborenea & Manceñido, 2005b); Sinemurian of Argentina (Damborenea, 1998, 2002a).

  • Paleoautoecology.—B, E, S, Un, FaM; R-Sw. In adult specimens, the byssal gape is not usually observed. Kolymonectes probably had an earlier byssate stage, but adults lived reclining on the substrate (Damborenea, 1998, 2002a). According to S. M. Stanley (1972), it was probably a good swimmer, since it had a thin shell, the valves were of the same convexity, the auricles were equal, and the umbonal angle was large enough to allow swimming cycles. Propeamusiids are currently restricted to deep environments, but this was not the case during the Jurassic, as they were present both in deep environments associated with low-oxygen facies (without other benthic organisms), and in coastal environments (Damborenea, 1998, 2002a).

  • Mineralogy.—Bimineralic (Damborenea, 1998). Damborenea (1998) proposed the presence of a calcitic outer shell layer at least in the right valve, based on indirect evidence, provided by the shell of specimens of Kolymonectes weaveri Damborenea, 1998. She also stated that the observed characters of the shell agree with the distribution of the shell layers in the family Propeamussiidae (see mineralogy for Parvamussium below).

  • Genus PARVAMUSSIUM Sacco, 1897, p. 48

  • Type species.—Pecten (Pleuronectes) duodecimlamellatum Bronn, 1831, p. 116.

  • Remarks.—Sacco (1897) distinguished 3 subgenera of Amussium: Propeamussium, species without ornamentation and large size, Eocene-Recent; Parvamussium, species very similar to Propeamussium but smaller, Cretaceous—Recent; and Variamussium, small shells internally ribbed, which include Jurassic forms, some Tertiary, and some modern forms. Subsequently, Cox and others (1969) regarded Variamussium as a junior synonym of Parvamussium, so that the arrangement was as follows; Propeamussium (Propeamussium) and Propeamussium (Parvamussium). Unfortunately, the stratigraphic ranges assigned to the two groups in Cox and others (1969) were mixed, and, from then on, Propeamussium sensu stricto was frequently cited from the Lower Jurassic, but these species should have been included in Parvamussium instead. Both groups are now recognized at the generic level (see Damborenea, 1998, p. 148–149). Parvamussium and Propeamussium can be distinguished as follows (Damborenea, 1998, p. 149); “In Propeamussium, no external sculpture, no byssal notch, equal auricles and a lateral gape, and, in Parvamussium, smaller size, well developed ornamentation on right valve, byssal notch and no lateral gape.”

  • Propeamussium is not included here because its revised stratigraphic range is from the Cretaceous to the present (see discussion in Genera not Included, p. 168).

  • Filamussium Waller, 2006 (type species; Pecten schafhäutli Winkler, 1859) is not included here, as we believe the proposition of this genus was unnecessary in view of the above (see discussion in Genera not Included, p. 161).

  • Following these arguments, specimens from the Triassic and Lower Jurassic (until Sinemurian) assigned to Propeamussium (Propeamussium) by Johnson (1984) and J. Yin and Grant-Mackie (2005), to Propeamussium (Variamussium) by Hautmann (2001b), and to Propeamussium by McRoberts (1997a), are considered to belong in Parvamussium.

  • Stratigraphic range.—Middle Triassic (Anisian)—Holocene (Nakazawa, 1961; Damborenea, 1998). Cox and others (1969) assigned to Parvamussium an Upper Cretaceous—Holocene range, but we explained above why we consider Parvamussium to range from the Triassic to the Recent. Although it was more abundant during the Late Triassic, especially during the Norian (see paleogeographic distribution, above), its oldest record is from the Anisian of Japan with Propeamussium (Variamussium) n. sp. indet. (Nakazawa, 1961).

  • Paleogeographic distribution.—Tethys, Circumpacific, and Boreal (Fig. 35). Although during our study interval we only find records from the Tethys and Circumpacific domains, later in the Jurassic the genus was also distributed in South America (Aberhan, 1994a, 1998b; Damborenea, 2002a) and Tibet (J. Yin & Grant- Mackie, 2005).

  • Tethys domain; Late Triassic; Norian of Iran (Hautmann, 2001b), western Carpathians (Kochanová, 1967; Kollarova & Kochanová, 1973); Rhaetian of Lombardy (Italy) (Allasinaz, 1962), Iran (Hautmann, 2001b); Early Jurassic: Sinemurian of ?Europe (Johnson, 1984).

  • Circumpacific domain; Middle Triassic; Anisian of Japan (Nakazawa, 1961); Late Triassic; Norian of Sonora (Mexico) (McRoberts, 1997a); Early Jurassic; Japan (Hayami, 1957b).

  • Boreal domain: Late Triassic; Norian of Arctic zone of Canada (Tozer, 1962).

  • Paleoautoecology.—B, E, S, Un, FaM; R-Sw. Most Recent species live in deep-water environments, their shells are very fragile, and this is a good place to be safe from predators (Beesley, Ross, & Wells, 1998). Some species can live 600 m deep, although they are also found in shallow water. They live freely reclining (Waller, 2006), and at least juveniles have a byssate stage in (Johnson, 1984; Damborenea, 2002a). Although a pseudoplanktonic mode of life was suggested for some propeamussiids, there is no morphological evidence (Johnson, 1984). Living species, at least, of Parvamussium can probably swim for short distances, since it is known that they feed on pelagic organisms (and benthic ones), and they may even actively catch them. A swimming habit is entirely compatible with their morphology (Johnson, 1984).

  • Mineralogy.—Bimineralic (Waller, 2006; but see Carter, 1990a, p. 256—257). Outer shell layer: calcite (prismatic). Middle shell layer: calcite (foliated). Inner shell layer: aragonite (cross-lamellar).

  • Figure 36.

    Paleogeographical distribution or Pectinidae (Chlamys, Weyla, Indopecten, Camptonectes, Crenamussium, Avichlamys, Pseudopecten, Agerchlamys, Canadonectites, Eopecten, Janopecten, Ochotochlamys, Tosapecten, Nevadapecten, Loxochlamys, Pleuronectites, Periclaraia, Radulonectites). 1, late Permian—Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f36_01.jpg

    Family PECTINIDAE Wilkes, 1810
    Genus CHLAMYS Röding in Bolten, 1798, p. 161

  • Type species.—Pecten islandicus Müller, 1776, p. 248. Remarks.—A synapomorphy of the subfamily Chlamydinae is the presence of aragonite cross-lamellar structure in the shell (Waller & Marincovich, 1992), but this feature only occurs in the specimens younger than the Tertiary. The inclusion of large numbers of Mesozoic species in the genus used in its broadest sense is an unsolved problem, and a review of Chlamys and other related genera diagnoses is needed (Damborenea, 2002a).

  • Although Praechlamys Allasinaz, 1972, was considered as a genus by some authors (e.g., Waller & Marincovich, 1992; Monari, 1994; Szente, 1996; Damborenea, 2002a), it was originally proposed as a subgenus of Chlamys. Other authors (e.g., Posenato, 2008b) still regard it as a subgenus of Chlamys, while Hautmann (2001b) questioned its validity altogether, since, in his opinion, the type of ornamentation is not an important taxonomic character at subgenus level. But Allasinaz (1972) used mainly differences in ornamentation to separate the subgenera C. (Chlamys), C. (Praechlamys), and C. (Granulochlamys). Until this controversy is solved, Praechlamys is here taken in its original sense. It is necessary to establish the diagnostic characters that define each taxon, because the diagnosis given by Allasinaz (1972) was too lax (Damborenea, 2002a). Some of the Triassic species traditionally attributed to Chlamys could fit into Praechlamys if considered at generic level, with an emended diagnosis, but other species are difficult to accommodate in other genera, and therefore a new taxon is required for them (Damborenea, 2002a).

  • As this discussion is beyond the scope of this paper, Chlamys is considered in a broad sense and present in the Triassic, but this is just a temporary solution for a group that has been particularly problematic since its conception.

  • Stratigraphic range.—Middle Triassic (Anisian)—Holocene (Cox & others, 1969; Waller, 2006). Cox and others (1969) assigned it a Triassic—Holocene range. According to Waller (2006), the oldest member of the subfamily Chlamydiinae is Praechlamys reticulata (Schlotheim, 1823 in 1822–1823) from the Anisian of Germany, but Hautmann (2010) stated that this species was not a pectinid. There are older records (e.g., Praechlamys wuxingensis Li, in Nanjing Institute of Geology and Mineral Resources, 1982, from the Lower Triassic of China), but those specimens are very doubtful pectinids (see Waller, 2006, p. 331).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 36).

  • Tethys domain; Middle Triassic; Anisian of Bosnia (Allasinaz, 1972), Italy (Posenato, 2008b), Switzerland (Zorn, 1971); Ladinian of Italy (Rossi Ronchetti, 1959; Allasinaz, 1972), Germany (Allasinaz, 1972), Spain (Márquez-Aliaga, 1983, 1985; López-Gómez & others, 1994), Slovakia (Kochanová, Mello, & Siblík, 1975), Malaysia (Tamura, 1973); Late Triassic; China (Wen & others, 1976; J. Chen, 1982a; Gou, 1993); Carnian of Italy (Allasinaz, 1966, 1972; Fürsich & Wendt, 1977), Switzerland, Hungary, and Bosnia (Allasinaz, 1972), Carpathians (Hungary) (Turculet, 1988), Spain (Martín-Algarra, Solé de Porta, & Márquez-Aliaga, 1995); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Czech Republic (Allasinaz, 1972), Austria (Allasinaz, 1972; Johnson, 1984), England (Johnson, 1984; Ivimey-Cook & others, 1999), Italy (Allasinaz, 1962; Johnson, 1984), Tibet (China) (J. Yin & McRoberts, 2006); Early Jurassic; Hettangian of England and France (Johnson, 1984; Liu, 1995), Italy (Allasinaz, 1962; Gaetani, 1970; Johnson, 1984), Wales (Johnson, 1984), Tibet (China) (J. Yin & McRoberts, 2006); Hettangian—Sinemurian of Spain (Calzada, 1982); Sinemurian of Switzerland (Johnson, 1984), Austria and Hungary (Szente, 1996), England, France, Spain, and Morocco (Liu, 1995), Vietnam (Sato & Westermann, 1991), Turkey (M. A. Conti & Monari, 1991).

  • Circumpacific domain; Late Triassic; Japan (Nakazawa, 1952; Tokuyama, 1959b); Carnian of Japan (Hayami, 1975); Norian of Oregon (United States) (Newton, 1986; Newton in Newton & others, 1987); Rhaetian of Nevada (United States) (Laws, 1982; Hallam & Wignall, 2000), Sonora (Mexico) (McRoberts, 1997a); Early Jurassic; Hettangian of Peru (Johnson, 1984); Hettangian—Sinemurian of Chile (Aberhan, 1994a); Sinemurian of western Canada (Aberhan, 1998a), Japan (Hayami, 1964, 1975).

  • Austral domain; Late Triassic; Rhaetian of Argentina (Riccardi & others, 2004); Early Jurassic; Hettangian-Sinemurian of Argentina (Damborenea, 2002a), of New Zealand (Damborenea & Manceñido, 1992); Sinemurian of Argentina (Damborenea & M anceñido, 2005b).

  • Boreal domain; Late Triassic; Carnian of Primorie (Kiparisova, 1972); Early Jurassic; Hettangian of northeastern Russia (Milova, 1976); Sinemurian of northeastern Russia (Polubotko & Milova, 1986).

  • Paleoautoecology.—B, E, S, Epi-Un, FaM; By-R-Sw. As inferred by functional morphology (Johnson, 1984), most fossil species probably lived attached by the byssus, at least during juvenile stages, in the same way that living species do. Many of them would be able to swim as well. Depending on the substrate in which they lived, they could spend most of their life as epibyssate on hard substrates. Other species are found in soft substrates, and these have spiny shells and probably lived reclined, using the spines to anchor them. See Johnson (1984) for a broad discussion on the ecology and modes of life of several species.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260). The group is very heterogeneous, and it is difficult to generalize about the microstructure of the shell layers (for details on the various species, see Carter (1990b, p. 381–383).

  • Genus WEYLA J. Böhm, 1922, p. 138

  • Type species.—Pecten alatus Buch, 1838, p. 55.

  • Remarks.—Although Damborenea (1987b) and Damborenea and Manceñido (1988) regarded Weyla as a neitheid, this family was not included in the systematic arrangement proposed by Amler (1999), which is followed here. Waller (2006) included this genus in the family Pectinidae by the presence of ctenolium.

  • Stratigraphic range.—Lower Jurassic (Hettangian—Toarcian) (Damborenea & Manceñido, 1988; Aberhan, 1994a). Cox and others (1969) assigned it a Upper Triassic—Middle Jurassic range, but they included three subgenera; W. (Weyla) from the Lower Jurassic, W (Pseudovola) Lissajous, 1923, p. 169, from the Middle Jurassic, and W. (Tosapecten) Kobayashi & Ichikawa, 1949b, p. 166, from the Upper Triassic. Currently, Pseudovola and Tosapecten are considered to be separate genera (Hayami, 1975; Damborenea, 1987b), so the remaining range is Lower Jurassic. We include two subgenera of Weyla from the Lower Jurassic, W. (Weyla) and W. (Lywed) Damborenea, 1987b. Damborenea and Manceñido (1988) indicated that the genus was present from Sinemurian to Toarcian, and subsequently it was found in Hettangian deposits (Aberhan, 1994a; Liu, 1995; Damborenea, 1996a). Lucas and Estep (1997, p. 45, fig. 1c and 1d) mentioned and figured Weyla from Carnian beds of Sonora (Mexico), but these specimens were reassigned to Mysidioptera by Damborenea in Damborenea and Gonzalez-León (1997); Lucas and Estep (1997) also reported other specimens from the Sinemurian of the same area.

  • Paleogeographic distribution.—Circumpacific and Austral (Fig. 36). Although the genus is also present in the Tethys domain, it is recorded there only after the beginning of the Pliensbachian (Calzada, 1982; Liu, 1995; Fraser, Bottjer, & Fischer, 2004; Valls, Comas-Rengifo, & Goy, 2004). The genus originated in the Pacific margin and then extended to the western Tethys through the Hispanic Corridor or Proto-Atlantic (Damborenea & Manceñido, 1979, 1988; Aberhan, 2001). See Damborenea and Manceñido (1979) for a complete distribution of the genus.

  • Circumpacific domain; Early Jurassic; Hettangian—Sinemurian of western Canada (Aberhan, 1998a), Mexico and Texas (Liu, 1995), Chile (Aberhan, 1994a); Sinemurian of Sonora (Mexico) (Damborenea in Damborenea & González-León, 1997; Lucas & Estep, 1997; Scholz, Aberhan, & González-León, 2008), Chile (Escobar, 1980), Peru (Rangel, 1978).

  • Austral domain; Early Jurassic; Sinemurian of Argentina (Damborenea & Manceñido, 2005b; Damborenea & Lanes, 2007).

  • Paleoautoecology.—B, Se, S, Un, Sed; R. From the observation of specimens in life position and analysis of the shell morphology (Damborenea & Manceñido, 1979, 1988; Damborenea, 1987b), it was inferred that Weyla was sedentary and lived semi-infaunally as a recliner, without byssus attachment in the adult stage.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260, 263). Little is known about the microstructure of the shell of Weyla; the inner shell layer is aragonitic and with cross-lamellar structure. Data provided for the family Pectinidae. Outer shell layer: calcite (prismatic). Inner shell layer: aragonite (cross-lamellar).

  • Genus INDOPECTEN Douglas, 1929, p. 632

  • Type species.—Pecten clignetti Krumbeck, 1913, p. 36.

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (Hautmann, 2001b). Cox and others (1969) assigned it an upper Norian range. New records expanded the range of this genus (see paleogeographic distribution).

  • Paleogeographic distribution.—Tethys (Fig. 36).

  • Tethys domain; Late Triassic; Norian of western Carpathians (Ruban, 2006a), China (Wen & others, 1976; J. Chen & Yang, 1983), Oman (R. Hudson & Jefferies, 1961), Armenia (Hautmann, 2001b), Timor (Indonesia) (Krumbeck, 1924), Himalayas (Kutassy, 1931), Thailand (Vu Khuc & Huyen, 1998); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Tibet (China) (Hautmann & others, 2005), Pamira (Afghanistan) (Polubotko, Payevskaya, & Repin, 2001).

  • Paleoautoecology.—B, E, S, Epi-Un, FaM; By-R-Sw. Some of Indopecten species, like I. glaber Douglas, 1929, could swim, as suggested by their ligament type (so-called alivinculat-alate according to Hautmann, 2004), which would be fit enough for the constant opening and closing of the valves required by a swimming activity (Hautmann, 2004). The external morphology is also compatible with a swimming habit, according to S. M. Stanley (1972). It probably lived mostly reclined, but it could swim occasionally. However, other species have a byssal notch, and their shell morphology is not suitable for swimming, so these were probably epibyssate (see Hautmann, 2001b).

  • Mineralogy.—Aragonitic (Hautmann, 2006a). According to Waller (2006), the Indopecten inner shell layers are usually recrystallized, so they were probably aragonitic. Although the microstructure of the outer shell layer is unknown, its mineralogy was calcific. However, Hautmann (2006a) studied the microstructure of two species of Indopecten [I. serraticostata (Bittner, 1899) and I. glaber Douglas, 1929)] and he concluded that all the shell was composed of a single microstructure (probably cross-lamellar) and was entirely aragonitic.

  • Genus CAMPTONECTES Agassiz in Meek, 1864, p. 39

  • Type species.—Pecten lens J. Sowerby, 1818, p. 3.

  • Remarks.—Cox and others (1969) included three subgenera within Camptonectes: C. (Camptonectes), C. (Camptochlamys) Arkell, 1930 in 1929—1937, p. 102, and C. (Boreionectes) Zakharov, 1965, p. 72. Subsequently, Allasinaz (1972, p. 316) added a fourth, C. (Annulinectes), and Fürsich (1982, p. 50) another, C. (Costicamptonectes). Kelly (1984) regarded Boreionectes as a junior synonym of Mclearnia Crickmay, 1930b, p. 45. According to Waller and Marincovich (1992), Costicamptonectes is unnecessary, and they raised Camptochlamys to generic level. We only consider two subgenera in our study interval; C. (Camptonectes) and C. (Annulinectes).

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Cretaceous (Maastrichtian) (Cox & others, 1969; Allasinaz, 1972). Cox and others (1969) assigned a Jurassic—Upper Cretaceous (Maastrichtian) range to C. (Camptonectes), but some Tertiary and Holocene species are now also referred to this genus by some authors (see Damborenea, 2002a, p. 56). Allasinaz (1972) assigned to C. (Annulinectes) an Anisian—Jurassic range, although the species he included in this subgenus were recorded only in Anisian, Ladinian, and Carnian beds. As we could not see the papers that recognize post-Cretaceous Camptonectes, we provisionally follow Cox and others (1969) for the end of the range.

  • Paleogeographic distribution.—Cosmopolitan (Fig. 36). Tethys domain: Middle Triassic: Anisian of Slovakia (Kochanová, 1985), Romania and Yugoslavia (Allasinaz, 1972); Ladinian of Slovakia (Kochanová, Mello, & Siblík, 1975), Bosnia (Allasinaz, 1972); Late Triassic: Carnian of Slovenia (Jelen, 1988), Hungary and Italy (Allasinaz, 1972); Rhaetian of ?England (Johnson, 1984; Ivimey-Cook & others, 1999); Early Jurassic: Hettangian of England (Johnson, 1984; Liu, 1995), Germany and Switzerland (Johnson, 1984); Sinemurian of England and Portugal (Liu, 1995).

  • Circumpacific domain: Late Triassic: Carnian of Japan (Nakazawa, 1952; Hayami, 1975); Early Jurassic: Hettangian of Japan (Hayami, 1959; Hayami, 1975; Johnson, 1984); Sinemurian of western Canada (Poulton, 1991; Aberhan, 1998a).

  • Austral domain: Early Jurassic: Hettangian—Sinemurian of Argentina (Damborenea, 2002a; Damborenea & Manceñido, 2005b).

  • Boreal domain: Late Triassic: Norian—Rhaetian of northeastern Russia (Milova, 1976).

  • Paleoautoecology.—B, E, S, Epi, FaM; By-Sw. All species described by Johnson (1984) have abyssal notch and were epibyssate. However, he interpreted that they could swim to escape from predators, on the basis of the analysis of external shell morphology (shell thin, low convexity, and wide umbonal angle). According to Sha (2003), Camptonectes had planktotrophic larvae that facilitated its global distribution.

  • Mineralogy.—Bimineralic (Johnson, 1984; Carter, 1990b, p. 381). Outer shell layer: calcite (foliated-prismatic). Inner shell layer: aragonite (?).

  • Genus CRENAMUSSIUM Newton in Newton & others, 1987, p. 46

  • Type species.—Crenamussium concentricum Newton in Newton & others, 1987, p. 50.

  • Remarks.—Newton (in Newton & others, 1987) included Crenamussium in the family Pectinidae. Later, Waller (in Waller & Stanley, 2005) included it in the Entoliidae, and a year later, Waller (2006) suggested that Crenamussium is a junior synonym of Calvaentolium Romanov, 1985, but he did not justify it. Calvaentolium is not included in this paper (see discussion in Genera not Included, p. 158). Newton (in Newton & others, 1987) included the type species in Crenamussium and, tentatively, C. balatonicus (Bittner, 1901b) (species included in Pleuronectites and Chlamys by other authors).

  • Stratigraphic range.—Upper Triassic (Carnian—Norian) (Newton in Newton & others, 1987). According to the species assigned by Newton (in Newton & others, 1987), the stratigraphic range of Crenamussium is Carnian—Norian.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 36). Tethys domain: Late Triassic: Carnian of Italy (Allasinaz, 1972), Hungary (Bittner, 1912), Carpathians (Kiparisova, 1954).

  • Circumpacific domain: Late Triassic: Norian of Oregon (United States) (Newton in Newton & others, 1987).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the diagnosis given by Newton (in Newton & others, 1987), the shell is subcircular, the auricles are unequal, and a deep byssal notch is observed in the right anterior auricle, thus it probably lived as an epibyssate.

  • Mineralogy.—Bimineralic (Newton in Newton & others, 1987, p. 50). Crenamussium shell microstructure is not well known, but the mineralogy of the shell, as a member of the family Pectinidae, should have at least a calcitic outer layer. In the specimens described by Newton (in Newton & others, 1987), there is evidence of original fibrous calcite in the form of siliceous pseudomorphs.

  • Genus AVICHLAMYS Allasinaz, 1972, p. 368

  • Type species.—Pecten csopakensis Frech, 1905, p. 4. Stratigraphic range.—Lower Triassic (Olenekian) (Posenato, 2008a). Allasinaz (1972) proposed Avichlamys and included two species: Pecten csopakensis Frech, 1905, and Pecten nicolensis Ogilvie Gordon, 1927, both from the Triassic. Subsequently, Neri and Posenato (1985) and Broglio-Loriga and others (1990) also included Chlamys tellinii To mm asi, 1896, which was reported from the Italian Triassic by Leonardi (1935) and Boni (1943).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 36).

  • Tethys domain: Early Triassic: Italy (Allasinaz, 1972; Neri & Posenato, 1985; Broglio-Loriga & others, 1990), Hungary (Allasinaz, 1972).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the generic diagnosis provided by Allasinaz (1972), Avichlamys is characterized by a subequivalve shell, with different valve convexity, subequal auricles, and a wide byssal gape in the right auricle. It was probably an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Carter, 1990a). No data are known about Avichlamys shell microstructure. We assume a bimineralic shell, as in the other pectinids, following Carter (1990a).

  • Genus PSEUDOPECTEN Bayle, 1878, explanation pl. 121

  • Type species.—Pecten equivalvis], Sowerby, 1816, p. 83.

  • Remarks.—Although Pseudopecten lacks a ctenolium and should be excluded from the Pectinidae (Damborenea, 2002a), we list it here until it is assigned to another family according to its features.

  • Stratigraphic range. —Lower Jurassic (Hettangian)—Middle Jurassic (Bajocian) (Johnson, 1984). Cox and others (1969) distinguished two subgenera within Pseudopecten: P. (Pseudopecten) and P. (Echinopecten) Brasil, 1895. Both were reported from Hettangian beds. However, following Johnson (1984), we regard P. (Pseudopecten) as Hettangian and P. (Echinopecten) as Toarcian. Therefore, only P. (Pseudopecten) is included in our study interval.

  • Paleogeographic distribution.—western Tethys (Fig. 36). During our study interval, Pseudopecten was only distributed in the western Tethys, but from the Pliensbachian onward, it was also reported from South America (Damborenea, 2002a) and Australia (Grant-Mackie, 1994). In addition, Damborenea (2002a) suggested that its presence in the Early Jurassic of Japan and Siberia is also possible.

  • Tethys domain: Early Jurassic: Hettangian of Spain (Liu, 1995), France, Italy, and Germany (Johnson, 1984); Sinemurian of Spain, Portugal, and Morocco (Liu, 1995), England (Johnson, 1984; Liu, 1995), Italy, France, and Germany (Johnson, 1984).

  • Paleoautoecology.—B, E, S, Un, FaM; R-Sw. Species attributed to P. (Pseudopecten) had a byssal gape at juvenile stages, but it disappeared in adult stages; they lived byssate when young but were later recliners on the substrate, and they could swim actively (see Johnson, 1984, for a complete interpretation of the various species).

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 388). Outer shell layer: calcite (prismatic + foliated). Inner shell layer: aragonite (cross-lamellar).

  • Genus AGERCHLAMYS Damborenea, 1993, p. 119

  • Type species.—Chlamys (Camptochlamys) wunschae Marwick, 1953, p. 98.

  • Stratigraphic range.—Upper Triassic (Carnian)—Lower Jurassic (Toarcian) (Damborenea, 1993, 2002a). Damborenea (1993) proposed Agerchlamys, including several previously described species referred to other genera (see Damborenea, 1993, p. 120, and Damborenea, 2002a, p. 66, for species listed). These species were recorded from the Carnian to the Toarcian, and the author indicated the possibility that the genus may be present up to the Middle Jurassic.

  • Paleogeographic distribution.—Circumpacific, Austral, and Boreal (Fig. 36). Agerchlamys was distributed through the Austral and Boreal domains and also in the Circumpacific, but always at high latitudes. In the Austral domain (Argentina and New Zealand), it was reported primarily from Pliensbachian beds (Marwick, 1953; Damborenea, 1993, 2002a).

  • Circumpacific domain; Early Jurassic; Hettangian of Chile (Aberhan, 1994a), Oregon (United States) (D. G. Taylor & Guex, 2002), British Columbia (western Canada) (Wignall & others, 2007); Hettangian—Sinemurian of Canada (Aberhan, 1998a, 1998b), Sonora (Mexico) (Scholz, Aberhan, & Gonzalez-León, 2008).

  • Austral domain; Early Jurassic; Hettangian—Sinemurian of Argentina (Damborenea, 2002b; Damborenea & Manceñido, 2005b).

  • Boreal domain; Late Triassic; Carnian—Norian of Siberia (Kiparisova, Bychkov, & Polubotko, 1966).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Due to the presence of a deep byssal gape below the right anterior auricle and a strong ctenolium, it was epibyssate (Damborenea, 1993, 2002a). Although it has a wide umbonal angle, the auricles are of different sizes, so it is not believed that it could swim.

  • Agerchlamys is usually found in low-energy and well-oxygenated environments, and associated with sponges and other bivalves, especially limids (Damborenea, 2002a).

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260). There are no data about Agerchlamys shell. We assume bimineralic mineralogy, as in the other members of the family Pectinidae (Carter, 1990a).

  • Genus CANADONECTITES Aberhan, 1998a, p. 110

  • Type species.—Canadonectites paucicostatus Aberhan, 1998a, p. 110.

  • Remarks.—Aberhan (1998a) proposed the genus Canadonectites to accommodate specimens with intermediate morphology between Pleuronectites Schlotheim, 1820, and Radulonectites Hayami, 1957c, and differing from both of them by ornamentation features.

  • Stratigraphic range.—Lower Jurassic (Sinemurian—Pliensbachian) (Aberhan, 1998a). It was only reported from Sinemurian and Pliensbachian beds of western Canada (Aberhan, 1998a).

  • Paleogeographic distribution.—Circumpacific (Fig. 36). Circumpacific domain; Early Jurassic; Sinemurian of western Canada (Aberhan, 1998a, 2001).

  • Paleoautoecology.—B, E, S, Epi, Se; By. The mode of life of Canadonectites was probably very similar to Agerchlamys, since both have a deep byssal notch and ctenolium in the right valve.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260). There are no data on Canadonectites shell microstructure. We assume bimineralic mineralogy, as in the other members of the family Pectinidae (Carter, 1990a).

  • Genus EOPECTEN Douvillé, 1897, p. 203

  • Type species.—Hinnites tuberculatus Goldfuss (errore pro Spondylus tuberculosus Goldfuss), 1835 in 1833–1841, p. 93.

  • Remarks.—See Johnson (1984, p. 149) and Damborenea (1987b, p. 198) for a discussion about synonymy and the problems related to this genus since its proposal.

  • Stratigraphic range.—Upper Triassic (Carnian)—Lower Cretaceous (Albian) (Hayami, 1975; Johnson, 1984). Cox and others (1969) assigned it a Jurassic—Lower Cretaceous (Albian) range. Although it seems fairly accepted that it appeared in the Early Jurassic, according to the literature, there are several records from the Carnian of Japan (Kobayashi & Ichikawa, 1949b; Nakazawa, 1952; Hayami, 1975) and from the Norian of Chile (Hayami, Maeda, & Ruiz-Fuller, 1977) that no other author except Hallam (1981) considered. Middle Triassic specimens assigned by Allasinaz (1972) to Radulonectites should be allocated to Eopecten instead (Damborenea, 2002a, p. 61). If Radulonectites? flagellum (Stoppani, 1858 in 1858–1860), described by Allasinaz (1972, p. 331), is assigned to Eopecten, the genus was present from Ladinian times. Another species that was referred to Eopecten, originally proposed as Monotis albertii Goldfuss, 1835 in 1833–1841 (Diener, 1923), was reported from the Lower and Middle Triassic of Europe, but it is currently included in Leptochondria (Waller & Stanley, 2005, p. 34).

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 36). According to the published records, it seems that Eopecten originated in the Late Triassic of Japan, and then it migrated to the western Tethys (Europe) and eastern Paleopacific.

  • Tethys domain; Early Jurassic; Hettangian of England (Liu, 1995), Belgium and Germany (Johnson, 1984); Sinemurian of Portugal and Spain (Liu, 1995), Germany (Johnson, 1984).

  • Circumpacific domain; Late Triassic; Carnian of Japan (Kobayashi & Ichikawa, 1949b; Nakazawa, 1952; Hayami, 1975); Early Jurassic; Hettangian of Chile (Aberhan, 1994a); Hettangian—Sinemurian of Canada (Aberhan, 1998a); Sinemurian of Canada (Poulton, 1991).

  • Austral domain; Early Jurassic; Hettangian—Sinemurian of Argentina (Riccardi & others, 1991; Damborenea, 2002a; Damborenea & Manceñido, 2005b).

  • Paleoautoecology.—B, E, S, Epi-C, Sed; By-C. Johnson (1984) and Harper and Palmer (1993) analyzed the mode of life of different species of Eopecten. The last authors concluded that some species could live cemented to the substrate, while others were epibyssate during most of their life.

  • Mineralogy.—Bimineralic (Carter, 1990b, p. 388; Harper & Palmer, 1993, p. 67). The shell of Eopecten had a foliated outer shell layer, both in the left valve (Carter, 1990a) and in the right one (Harper & Palmer, 1993), and aragonitic middle and inner shell layers with cross-lamellar microstructure (Carter, 1990a).

  • Genus JANOPECTEN Arkhipov & Trushchelev, 1980, p. 10

  • Type species.—Janopecten kularensis Arkhipov & Trushchelev, 1980, p. 10.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (lower Carnian) (Waller in Waller & Stanley, 2005). Janopecten was reported from Anisian and Ladinian beds (Dagys & Kurushin, 1985) and from the lower Carnian of the Boreal area (Waller in Waller & Stanley, 2005).

  • Paleogeographic distribution.—Boreal (Fig. 36).

  • Boreal domain; Middle Triassic; Anisian of Yakutia (Russia) (Konstantinov, Sobolev, & Yadernkin, 2007); Anisian—Ladinian of Siberia (Arkhipov & Trushchelev, 1980; Dagys & Kurushin, 1985). Late Triassic; early Carnian of Siberia (Arkhipov & Trushchelev, 1980).

  • Paleoautoecology.—B, E, S, Epi, FaM; By-Sw? At least the type species (Dagys & Kurushin, 1985, pl. 21,13a,13b) had an equivalve shell, nearly equal auricles, and an umbonal angle large enough to be an occasional swimmer. The shells had a byssal notch throughout their ontogeny (Waller in Waller & Stanley, 2005), and they likely lived epibyssate and occasionally could perform swimming cycles. This is probably true only for the Anisian forms, since, according to Waller (in Waller & Stanley, 2005), Ladinian and Carnian species of Janopecten began to develop strongly inequilateral shells.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260). There are no data on Janopecten shell microstructure. Bimineralic mineralogy is assumed, as in the other members of the family Pectinidae.

  • Genus OCHOTOCHLAMYS Milova & Polubotko in Milova, 1976, p. 61

  • Type species.—Chlamys (Ochotochlamys) gizhigensis Polubotko in Milova, 1976, p. 61.

  • Remarks.—Ochotochlamys was erected as subgenus of Chlamys (Milova & Polubotko in Milova, 1976), but it was subsequently raised to genus level (Polubotko & Milova, 1986), which was followed by all later authors.

  • Stratigraphic range.—Upper Triassic (Norian)—Lower Jurassic (Toarcian) (Milova & Polubotko in Milova, 1976; Aberhan, 1998a). For a long time, Ochotochlamys was only reported from Late Triassic of northeastern Asia, but it was later recorded from the Pliensbachian (Polubotko & Milova, 1986; Aberhan 1998a; Damborenea, 2002a) and from the Toarcian (Aberhan, 1998a).

  • Paleogeographic distribution.—Boreal (Fig. 36). It was originally believed that the genus was restricted to northeastern Asia, but new records from the Pacific margin (Canada and Argentina) (Aberhan, 1998a; Damborenea, 2002b) extended its paleogeographic distribution; but it is only known from high paleolatitudes. The Austral record is Pliensbachian and thus outside our study range (Damborenea, 2002a). It was also mentioned from the Triassic—Jurassic boundary beds of British Columbia (Wignall & others, 2007) and eastern Alberta (Asgar-Deen & others, 2003).

  • Boreal domain; Late Triassic; Carnian—Norian of northeastern Asia (Polubotko & Milova in Milova, 1976); Early Jurassic; Hettangian of northeastern Russia (Milova, 1988); Hettangian-Sinemurian of western Canada (Aberhan, 1998a, 1998b, 2001); Sinemurian of northeastern Russia (Polubotko & Milova, 1986).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to Aberhan (1998a), a typical feature of the genus is that the right anterior auricle had a byssal notch; a byssal sinus is observed in the left valve, but it is not distinguishable in all specimens. Ochotochlamys was probably an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260). There are no data on Ochotochlamys shell microstructure. Bimineralic mineralogy is assumed, as in the other members of the family Pectinidae (Carter, 1990a).

  • Genus TOSAPECTEN Kobayashi & Ichikawa, 1949b, p. 166

  • Type species.—Pecten (Velopecten) suzukii Kobayashi, 1931, p. 258.

  • Remarks.—Although Kobayashi and Ichikawa (1949b) proposed Tosapecten within the family Pectinidae, Cox and others (1969) considered it to be a subgenus of Weyla Böhm, 1922. Currently, almost all authors (Hayami, 1975; Milova, 1976; J. Chen, 1982a; Okuneva, 1985; Damborenea, 1987b; Tanaka, 1989; Waller in Waller & Stanley, 2005; Waller, 2006) regard it as a distinct genus, separate from Weyla.

  • According to Waller (in Waller & Stanley, 2005), Tosapecten includes two sub genera, T. (Tosapecten) and T. (Indigiropecten) Trushchelev, 1984.

  • Stratigraphic range.—Upper Triassic (Carnian—Rhaetian) (Kobayashi & Ichikawa, 1949b; Milova, 1976). Cox and others (1969) stated that the genus was known from the Upper Triassic of Japan. Subsequently, it was also reported from Siberia (Kobayashi & Tamura, 1983b). It was known throughout the Carnian and Norian in Japan (see paleogeographic distribution, below). We lack information on the Siberian records; we could only check the Norian occurrence in Okuneva (1985). Milova (1976) reported Tosapecten subhiemalis wittnburgi n. subsp. from upper Norian—Rhaetian beds. Some biostratigraphic papers mentioned the presence of Tosapecten from latest Triassic times (Kurushin, 1990; Polubotko & Repin, 1990; Zakharov & others, 1997), referring to Tosapecten efimovae Polubotko, 1966.

  • Paleogeographic distribution.—Circumpacific and Boreal (Fig. 36). Tosapecten was mainly distributed through the northern Circumpacific and Boreal domains.

  • Circumpacific domain; Late Triassic; Carnian of Japan (Nakazawa, 1952; Ando, 1988); Carnian—Norian of Japan (Kobayashi & Ichikawa, 1949b; Tokuyama, 1959b; Hayami, 1975; Tanaka, 1989; Onoue & Tanaka, 2005); Norian of Japan (Nakazawa, 1963), ?Oregon (United States) (Newton in Newton & others, 1987; Newton, 1988).

  • Boreal domain; Late Triassic; Carnian of northeastern Russia (Bychkov & others, 1976), Primorie (Kiparisova, 1972); Norian of Siberia (Okuneva, 1985); Norian—Rhaetian of northeastern Russia (Milova, 1976); Rhaetian of northeastern of Siberia (Bychkov & others, 1976; McRoberts, 2010).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. In all species assigned to Tosapecten, a byssal notch is observed, and they have unequal auricles (see description and figures in the published literature, listed above). Like most pectinids, they lived epibyssate.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 260). There are no data on Tosapecten shell microstructure. Bimineralic mineralogy is assumed, as in the other members of the family Pectinidae.

  • Genus NEVADAPECTEN
    Waller in Waller & Stanley, 2005, p. 46

  • Type species.—Nevadapecten lynnae Waller in Waller & Stanley, 2005, p. 46.

  • Remarks.—Waller (in Waller & Stanley, 2005) included Nevadapecten in the subfamily Tosapectininae and related it with Tosapecten and Janopecten, considering it to be intermediate between these two genera in several aspects.

  • Stratigraphic range.—Middle Triassic (upper Ladinian) (Waller in Waller & Stanley, 2005). According to Waller (in Waller & Stanley, 2005), Nevadapecten was reported from the upper Ladinian of New Pass Range in Nevada.

  • Paleogeographic distribution.—Circumpacific (Fig. 36).

  • Circumpacific domain: Middle Triassic: Ladinian of Nevada (United States) (Waller in Waller & Stanley, 2005).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Nevadapecten had some features related to a swimming mode of life, such as circular shape, an almost equilateral shell, and a wide umbonal angle, but it had unequal auricles and a byssal gape, which indicates it was an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Waller in Waller & Stanley, 2005). Outer shell layer: calci te (antimarginal fibrous). Inner shell layer: aragonite.

  • Genus LOXOCHLAMYS
    Waller in Waller & Stanley, 2005, p. 40

  • Type species.—Loxochlamys corallina Waller in Waller & Stanley, 2005, p. 43.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Carnian) (Waller in Waller & Stanley, 2005). Waller (in Waller & Stanley, 2005) included the type species within Loxochlamys, from the upper Ladinian, and two other species: Pecten chiwanae McLearn, 1941, and Pecten sasuchan McLearn, 1941, both from Carnian beds.

  • Paleogeographic distribution.—Circumpacific (Fig. 36).

  • Circumpacific domain: Middle Triassic: Ladinian of Nevada (United States) (Waller in Waller & Stanley, 2005); Late Triassic: Carnian of British Columbia (Canada) (McLearn, 1941; Waller in Waller & Stanley, 2005).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Loxochlamys had a byssal notch and ctenolium throughout its ontogeny; it probably lived epibyssate among corals with which it was usually associated (Waller in Waller & Stanley, 2005).

  • Mineralogy.—Bimineralic (Waller in Waller & Stanley, 2005). Outer shell layer: calci te (antimarginal fibrous). Inner shell layer: aragonite.

  • Genus PLEURONECTITES von Schlotheim, 1820, p. 217

  • Type species.—Pleuronectites laevigatus von Schlotheim, 1820, p. 217.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Triassic (Carnian) (Hayami, 1975; Waller, 2006). Newell and Boyd (1995) extended the range of Pleuronectites to the Lower Triassic, with the species Pleuronectites meeki Newell & Boyd, 1995, but Waller (in Waller & Stanley, 2005) regarded this species as an entoliid rather than a pectinid, because it lacks a ctenolium. Waller (2006) indicated that the oldest undoubted Pleuronectites is P. laevigata Schlotheim, 1820, from the Anisian (see Waller in Waller & Stanley, 2005 and Waller, 2006, for records mentioned from the Lower Triassic that are not taken into account). The youngest record of the genus is from the Carnian with P. hirabarensis Amano (Hayami, 1975). Newton (in Newton & others, 1987) mentioned it from the Norian, but this reference is questionable.

  • Hautmann (2010) considered most species attributed to Pleuronectites to be synonyms of P. laevigatus (previously referred by Waller in Waller & Stanley, 2005, to Pecten laterestriatus Philippi, 1899, and Pecten schmiederi Giebel, 1856) or as erroneusly assigned to the genus, so Pleuronectites would be a monospecific genus. The author, and previously Waller (in Waller & Stanley, 2005), mentioned P. balatonicus (Bittner, 1901c), figured by Allasinaz (1972), and regarded it as entoliid. Pleuronectites newelli Waller in Waller & Stanley, 2005, was also regarded as an entoliid by Hautmann (2010). He assigned an Anisian—Ladinian range to Pleuronectites, but he did not mention Amanos Carnian species.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 36).

  • The paleogeographic distribution agrees with Waller (in Waller & Stanley, 2005) and Waller (2006). Although Pleuronectites is often quoted as being from China, the specimens are uncertainly or erroneously assigned (Waller in Waller & Stanley, 2005).

  • Tethys domain: Middle Triassic: Anisian of Germany (Hagdorn, 1982, 1991, 1995); Anisian—Ladinian of Israel (Lerman, 1960), Germany, Hungary, Sardinia (Italy), Afghanistan, and China (Hautmann, 2010); Ladinian of Italy (Allasinaz, 1972), Spain (Márquez-Aliaga, 1983, 1985), Afghanistan (Farsan, 1972).

  • Circumpacific domain: Middle Triassic: Anisian of Japan (Hayami, 1975); Ladinian of Nevada (United States) (Waller in Waller & Stanley, 2005); Late Triassic: Carnian of Japan (Hayami, 1975).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. According to the diagnosis offered by Waller (in Waller & Stanley, 2005), Pleuronectites probably lived epibyssate, and it had a deep byssal notch below the right anterior auricle, and a ctenolium throughout ontogeny.

  • Mineralogy.—Bimineralic (Waller in Waller & Stanley, 2005, p. 40). Pleuronectites newelli Waller in Waller & Stanley, 2005, shows an originally aragonitic inner shell layer and a calci tic outer shell layer (Waller in Waller & Stanley, 2005), and the same mineralogy was found in Pleuronectites laevigatus Schlotheim, 1820 (Hautmann, 2010; Carter & Hautmann, 2011); the microstructure of inner and middle shell layers was probably cross-lamellar, and the outer shell layer was prismatic.

  • Genus PERICLARAIA J. Li & Ding, 1981, p. 327, 330

  • Type species.—Periclaraia circularis J. Li & Ding, 1981, p. 327.

  • Remarks.—Periclaraia was proposed by J. Li and Ding (1981) from deposits of Anhui Province (China). These authors included three species: Periclaraia circularis J. Li & Ding, 1981, Periclaraia reticulata J. Li & Ding, 1981, and Periclaraia chaoxianensis J. Li & Ding, 1981. Subsequently, J. Chen and Komatsu (2002) added a new species, Periclaraia jinyaensis Chen & Komatsu, 2002, and they considered that the three species proposed by J. Li and Ding (1981) are variants of the same, as J. Li and Ding (1981) used differences in ornamentation and size of the right anterior auricle to separate them. These variations are regarded as intraspecific by J. Chen and Komatsu (2002). J. Li and Ding (1981) included Periclaraia in the family Pectinidae, but other authors (H. Yin, 1985, 1990; Gavrilova, 1995, 1996), based on its external resemblance to the clariids, referred it to the Pteropectinidae. However, J. Chen and Komatsu (2002) argued that since Periclaraia had a right valve ctenolium, a diagnostic character of the family Pectinidae, it should be included in this family.

  • Stratigraphic range.—Lower Triassic (upper Olenekian)—Middle Triassic (lower Anisian) (J. Li & Ding, 1981; J. Chen & Komatsu, 2002). J. Li and Ding (1981) reported Periclaraia from upper Olenekian beds of Anhui Province (China). Subsequently, J. Chen and Komatsu (2002) mentioned it from lower Anisian deposits of Guangxi province (China) and doubted the age assignation given by J. Li and Ding (1981). However, Periclaraia was quoted in several biostratigraphic papers in Anhui province in beds attributed to the Olenekian (Tong & others, 2004, 2006; Tong, 2005; S. Wu & others, 2005). Curiously, these papers considered Periclaraia as endemic to Anhui province, not mentioning J. Chen and Komatsu (2002).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 36).

  • Tethys domain; Early Triassic; late Olenekian of Anhui province (China) (J. Li & Ding, 1981); Middle Triassic; early Anisian of Guangxi province (China) (J. Chen & Komatsu, 2002; J. Chen & Stiller, 2007).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. The features of Periclaraia shells, which are inequivalve and inequilateral and had a deep byssal notch, indicate it was probably an epibyssate bivalve.

  • Mineralogy.—Bimineralic (Carter, Barrera, & Tevesz, 1998). Mineralogical data provided for the family Pectinidae by Carter, Barrera, and Tevesz (1998). Outer shell layer: calcite. Middle and inner shell layers; calcite-aragonite.

  • Genus RADULONECTITES Hayami, 1957c, p. 89

  • Type species.—Radulonectites japonicas Hayami, 1957c, p. 90.

  • Remarks.—Hunanonectes Z. Fang, 1978, p. 465, is considered to be a synonym of Radulonectites (see discussion for Hunanonectes in Genera not Included, p. 162).

  • Stratigraphic range.—Lower Jurassic (Hettangian—Pliensbachian) (Stiller, 2006; Hayami, 1975). Hayami (1957c) proposed the genus from the Japanese Pliensbachian (see also Hayami, 1985) and included the type species and Pecten (Pleuronectites) laterestriatus Philippi, 1899, from the German lower Muschelkalk, and also specimens referred by A. F. Leanza (1942) to Pecten (Camptonectes) lens Sowerby from the Pliensbachian of Argentina. He also provisionally included Chlamys kakanuia Marwick (1956, fig. 1) from the Upper Triassic of New Zealand, a species based on too poorly preserved material to discuss its affinities (Damborenea, 1993, 2002a). Later, Hayami (1975) disregarded these Triassic records and assigned the genus a Pliensbachian range. Cox and others (1969) referred it to the ?Triassic, Lower Jurassic. On the other hand, Sepkoski (2002) assigned it a Triassic (Anisian)—Jurassic (?Pliensbachian) range, mentioning Hayami (1975) and H. Yin (1985) as his sources. H. Yin (1985) mentioned it during Anisian and Ladinian but did not list the original source. Allasinaz (1962, 1972) quoted Radulonectites from the European Triassic. The specimens from the Italian Rhaetian referred by Allasinaz (1962) to Radulonectites are very poorly preserved; these doubtful records are not taken into account here, since, according to Damborenea (2002a), they belong to Eopecten Douvillé, 1897. The same occurs with material from the Triassic of New Zealand, similarly referred by other authors (see Damborenea, 2002a, p. 61). Onoue and Tanaka (2005) mentioned Radulonectites sp. from the Japanese Upper Triassic, based on a single deformed specimen, and their incomplete description is not enough to extend the range of this taxon. The oldest solid records are Hettangian (J. Chen, 1982b; Stiller, 2006 [Hunanonectes]) and the youngest are Pliensbachian (Hayami, 1957c, 1975, 1985).

  • Paleogeographic distribution.—Eastern Tethys (Fig. 36). During the Pliensbachian, this genus had a wide distribution (e.g., Siberia, Argentina, Chile) (Hayami, 1975; Polubotko & Milova, 1986; Milova, 1988; Damborenea, 1993, 2002a; Aberhan, 1994a, 1998a; Aberhan & Fürsich, 1997), and during the study interval, it was only reported with certainty from China.

  • Tethys domain; Early Jurassic; Hettangian—Sinemurian of southern China (J. Chen, 1982b, 1988; Z. Fang, 1978; Stiller, 2006); ?Sinemurian of Canada (Poulton, 1991, according to Aberhan, 1998a).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Several morphological traits (shell shape, convexity of valves, and the presence of deep byssal notch) and the encrusted epizoic organisms in several specimens suggest an epibyssate mode of life (Damborenea, 2002a).

  • Mineralogy.—Bimineralic (Carter, Barrera, & Tevesz, 1998). Mineralogical data provided for the family Pectinidae by Carter, Barrera, and Tevesz (1998). Outer shell layer: calcite. Middle and inner shell layers; calcite-aragonite.

  • Family ENTOLIIDAE Teppner, 1922

  • Syncyclonemidae Waller, 1978

  • In recent years, various genera for different groups of species that were traditionally referred to Entolium were proposed. This is very similar to what happened to the family Halobiidae, but there is no consensus about which characters should be used to discriminate between different taxonomic levels (see Damborenea, 2002a, p. 42—44, for a full discussion on the subject). Features that are distinctive at species level, according to some authors (see Johnson, 1984), are used by others to discriminate at genus level (Damborenea, 2002a): the presence or absence of lateral internal ribs; the presence or absence of byssal notch; and dorsal projection of the auricles. Furthermore, some surface shell structures are used at genus level, even if they are strongly influenced by diagenetic processes (Johnson, 1984; Damborenea, 2002a). In the absence of a good review on the subject, we are not taking into account the genera listed below (see discussion for each of them in Genera not Included, p. 156), since their proposition was based, in most cases, on diagnostic characters that are used by most authors at species level, and they can all be grouped under Staesches (1926) original concept of Entolium: Costentolium Freneix, 1980, p. 89; Cingentolium Yamani, 1983, p. 6; Neoentolium Romanov, 1985, p. 37; Cornutoentolium Romanov, 1985, p. 52 (Upper Jurassic); Calvaentolium Romanov, 1985, p. 35; and Palaeontolium Romanov, 1985, p. 35. All of these nominal genera, except Cornutoentolium, were recorded as being in our study interval.

  • Waller (2006) proposed a new family, Entoliolidae Waller, 2006 and included within it the genera Filopecten Allasinaz, 1972, p. 301; Entolioides Allasinaz, 1972, p. 295; Scythentolium Allasinaz, 1972, p. 308; and Calvaentolium (=Crenamussium Newton in Newton & others, 1987, p. 46), thus grouping the old Triassic entoliids with filosus structure and a deep byssal notch, and lacking internal ribs. Waller (2006) regarded this family as the link between Pernopecten and Mesozoic pectinids. On the other hand, other authors (H. Yin, 1983; Nakazawa, 1996) argued that the distinction between Pernopecten and Entolium is just a matter of convenience, using the first name for Paleozoic specimens and the second for Mesozoic ones. In fact, H. Yin (1983) reported Entolium from the upper Permian, like other authors, and Nakazawa (1996) reported Pernopecten from the Lower Triassic. This issue remains unresolved until future research is done. We provisionally follow Newell and Boyd (1995) in their suggestion that Pernopecten was a Paleozoic genus.

  • In view of the significant discrepancies between different authors, this discussion is beyond the purpose of this study, and, while there is no consensus on the diagnostic characters for each taxonomic level, we regard Entolium in its original sense (see Damborenea [2002a] for Staesche's concept [1926]).

  • Figure 37.

    Paleogeographical distribution or Entoliidae (Entolium, Scythentolium, Filopecten, Posidonotis, Entolioides). 1, Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f37_01.jpg

    Genus ENTOLIUM Meek, 1865, p. 478

  • Type species.—Pecten demissus Meek, 1865, p. 478.

  • Stratigraphic range.—Lower Triassic—Upper Cretaceous (Maastrichtian) (Allasinaz, 1972; Abdel-Gawad, 1986). Cox and others (1969) assigned it a Middle Triassic—Upper Cretaceous range. The youngest record is from the Maastrichtian (Abdel-Gawad, 1986) and the oldest one from the Lower Triassic (E. discites Schlotheim, 1820).

  • Paleogeographic distribution.—Cosmopolitan (Fig. 37). In the Boreal domain, in addition to the Triassic, it was also recorded in the Early Jurassic (Kurushin, 1990; Polubotko & Repin, 1990), but the specimens were not figured or discussed. Milova (1976) reported it from the Pliensbachian and Milova (1988) from the Toarcian of northeastern Russia.

  • Tethys domain; Early Triassic; Italy (Allasinaz, 1972; Neri & Posenato, 1985), China (C. Chen, 1982; S. Yang, Wang, & Hao, 1986); Middle Triassic; Hungary (Allasinaz, 1972; Szente, 1997), Germany (Bachmann, 1973; Hagdorn, 1995), Poland (Senkowiczowa, 1985); Anisian of Italy (Allasinaz, 1972; Posenato, 2008b), China (Gu & others, 1976; Sha, Chen, & Qi, 1990; J. Chen, 2003), Bulgaria (Tronkov & Damyanov, 1993), Bosnia and Yugoslavia (Allasinaz, 1972), northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of Spain (Márquez-Aliaga, 1983, 1985; Márquez-Aliaga & Montoya, 1991; Budurov & others, 1991; López-Gómez & others, 1994), China (Gu & others, 1976), Malaysia (Tamura, 1973), Italy (Rossi Ronchetti, 1959; Allasinaz, 1972), northern Vietnam (Komatsu, Huyen, & Huu, 2010), Afghanistan (Farsan, 1972); Late Triassic; Carnian of the Alps (Allasinaz, 1966, 1972; Fürsich & Wendt, 1977; Hautmann, 2001b), Spain (Martín-Algarra, Solé de Porta, & Márquez-Aliaga, 1995), China (Gu & others, 1976; Sha, Chen, & Qi, 1990); Norian of China (Lu, 1981); Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of ?Tibet (“Lhasa Block”) (J. Yin & Grant-Mackie, 2005), Alps (Vöros, 1981; Hautmann, 2001b), Hungary (Vörös, 1981; Hautmann, 2001b), Italy (Sirna, 1968); Early Jurassic; Hettangian of the Alps (Johnson, 1984), Germany and France (Vörös, 1971; Johnson, 1984), Vietnam (Vu Khuc & Huyen in Sato & Westermann, 1991).

  • Circumpacific domain; Early Triassic: Olenekian of Japan (Nakazawa, 1961; Hayami, 1975; Kashiyama & Oji, 2004); Middle Triassic: Japan (Hayami, 1975; Tamura & others, 1978); Early Jurassic: Hettangian of Chile (Hillebrandt, 1990); Hettangian—Sinemurian of Canada (Aberhan, 1998a; Aberhan, Hrudka, & Poulton, 1998), Chile (Aberhan, 1993, 1994a); Sinemurian of Japan (Hayami, 1975), Canada (Poulton, 1991).

  • Austral domain: Early Jurassic: Sinemurian of Argentina (Damborenea, 2002a; Damborenea & Manceñido, 2005b).

  • Boreal domain: Middle Triassic: Anisian of Siberia (Dagys & Kurushin, 1985); Late Triassic: Carnian of Primorie (Kiparisova, 1972); Norian of Siberia (Okuneva, 1985).

  • Paleoautoecology.—B, E, S, Un, FaM-Sed; R-Sw. Young specimens of Entolium s.s. had a byssal notch, but this was lost in adult stages. The life habit also probably changed from epibyssate in early stages to reclined in the upper ones. The low convexity of the shell, its reduced thickness, its circular outline, and the wide umbonal angle are characteristics that indicate it could have been a good swimmer, like some living pectinids (Johnson, 1984). However, in our provisional, broad concept of Entolium, there are some species that retained the byssal notch until the adult stages and therefore were epibyssate their entire lives.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 257). The family Entoliidae is characterized by bimineralic mineralogy (Carter, 1990a), with different microstructure types in juveniles and adults (homogeneous, simple prismatic, foliated, and fibrous prismatic), and a cross-lamellar inner shell layer (see Allasinaz, 1972; Waller, 1978; Johnson, 1984, among others, for more information).

  • Genus SCYTHENTOLIUM Allasinaz, 1972, p. 308

    Genus FILOPECTEN Allasinaz, 1972, p. 301

  • Type species.—Pecten filosus Hauer, 1857, p. 30.

  • Remarks.—Allasinaz (1972) included in Filopecten the following species: F. filosus (Hauer); F. schlosseri (Woehrmann); F. incognitus (Bittner); F. azzarolae (Stopanni); F. helii (Emmrich); F. aff. discites (Cox); F. fimbriatus (Mansuy); F. quotidianus (Healey); F. kolymaensis (Kiparisova); and with doubts, Pecten rosaliae (Salomon, 1895). However, Waller (in Waller & Stanley, 2005) suggested that the last species should not be included, since, among other differences, it has a ctenolium, which is absent in all members of family Entoliidae. Filopecten is very similar to Entolium concerning the shape of the auricles, the general external form, and even the hinge, and they differ in the byssal notch and ornamentation (Allasinaz, 1972). According to Hautmann (2001b), these features should not be used for generic distinction within the family. In fact, Hautmann (2001b) included the species incognitum (Bittner, 1901c), which was transferred to Filopecten by Allasinaz (1972), into Entolium (Entolium).

  • Stratigraphic range.—Upper Triassic (Carnian—Rhaetian) (Allasinaz, 1972). According to the species listed by Allasinaz (1972), the genus had an Upper Triassic range.

  • Paleogeographic distribution.—Tethys and Boreal (Fig. 37).

  • Tethys domain: Late Triassic: China (Diener, 1923); Carnian of the Alps and Hungary (Allasinaz, 1972); Rhaetian of the Alps and Hungary (Allasinaz, 1972), Burma (Healey, 1908), Indochina (Allasinaz, 1972).

  • Boreal domain: Late Triassic: Siberia (Allasinaz, 1972).

  • Paleoautoecology.—B, E, S, Epi, Sed; By. Similar to Scythentolium.

  • Mineralogy.—Bimineralic (Carter, 1990a, p. 257). See mineralogy for Entolium.

  • Genus POSIDONOTIS Losacco, 1942, p. 11

  • Type species.—Posidonotis dainelii Losacco, 1942, p. 11.

  • Remarks.—Following Damborenea (1986, 1987b), we regard Pectinula A. F. Leanza, 1943, p. 241, as a junior synonym of Posidonotis (see discussion for Pectinula in Genera not Included, p. 167), and we include Posidonotis in the family Entoliidae, although not all authors agree with this (see Hayami, 1988; Aberhan, 1994a, 1998a; Monari, 1994; Waller, 2006). Cox and others (1969), as well as most mentioned authors, included it within the family Posidoniidae. Pectinula was assigned to Pectindae by A. F. Leanza (1943), and this was followed by Cox and others (1969).

  • Stratigraphic range.—Lower Jurassic (Sinemurian—Toarcian) (Damborenea, 1987b). Cox and others (1969) assigned Posidonotis to the Middle Jurassic (Aalenian) and Pectinula to the Lower Jurassic. The range assigned by Cox and others (1969) to Posidonotis was taken from Losacco (1942), who reported it from Aalenian deposits, but these were later redated as Toarcian (see Damborenea, 1987b, p. 192–193).

  • Paleogeographic distribution.—Circumpacific (Fig. 37). During our study interval, it was only present on the eastern coast of the Paleopacific, but during the Pliensbachian its distribution was broader (see Damborenea, 1986, 1987b; Hayami, 1988; Monari, 1994).

  • Circumpacific domain: Early Jurassic: Sinemurian of Chile (Aberhan, 1994a, 1998a), California (United States) and British Columbia (Canada) (Damborenea, 1986, 1987b; Aberhan & Pály, 1996).

  • Paleoautoecology.—B, E, S, Un, Sed; R. Several authors (e.g., Hayami, 1969a, 1988; Hillebrandt, 1981) suggested a pseudoplanktonic mode of life for Posidonotis, because it is often found in black shales with no associated benthic fauna. This mode of life is unlikely, because byssal structures are not present in adult specimens, although juveniles had them. In addition, other modes of life have been suggested, as nektoplanktonic, benthic with chemosymbiotic organisms, or teleplanic larvae (see Aberhan & Pálfy, 1996). However, the most plausible mode of life during the adult stages is reclining on soft substrates; in young stages, it was a byssate bivalve (Aberhan & Pálfy, 1996). Some species are interpreted as opportunistic, as they were recorded in great abundance in facies poor in oxygen, where only ammonoids are found (Damborenea, 1987b; Aberhan & Pálfy, 1996).

  • Mineralogy.—Bimineralic (Carter, Barrera, & Tevesz, 1998). See mineralogy for Entolium.

  • Genus ENTOLIOIDES Allasinaz, 1972, p. 295

  • Type species.—Pecten zitteli Wöhrmann & Koken, 1892, p. 173.

  • Stratigraphic range.—Lower Triassic—Upper Triassic (Carnian) (Allasinaz, 1972; Newell & Boyd, 1995). Allasinaz (1972) assigned to Entolioides a Middle—Upper Triassic range, but all species he included were only recorded from Carnian deposits [E. deeckei (Parona, 1889); E. lavaredanus (Frech, 1904); E. porschei (Toula, 1913); E. setinus (Gortani, 1902); E. subdemissus (Münster, 1841); and E. zitteli (Wöhrmann & Koken, 1892)], according to the range listed on p. 222 of his monograph. Newell and Boyd (1995) reported the type species (Pecten zitteli) from the Middle Triassic of the Alps, but Allasinaz (1972) reported it from the Carnian of the southern Alps, and we only found it mentioned from this stage. Newell and Boyd (1995) reported the species Entolioides utahensis (Meek, 1877) from the Lower Triassic of the Thaynes Formation.

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 37).

  • Tethys domain: Late Triassic: Carnian of the Alps (Allasinaz, 1972).

  • Circumpacific domain: Early Triassic: Idaho, Montana, and Nevada (United States) (Newell & Boyd, 1995).

  • Paleoautoecology.—B, E, S, Epi, FaM; By-Sw. Two groups can be distinguished within pectinoideans regarding their mode of life (S. M. Stanley, 1972): some are epibyssate, and they are characterized by different convexity in both valves, the anterior auricle being more developed, and a byssal sinus throughout their ontogeny; others, with more symmetrical shell with both valves similarly convex, have auricles of the same shape and size, and an umbonal angle greater than 90°, are also epibyssate but with the ability to swim. Both valves in Entolioides were nearly equally convex, with subequal auricles, an umbonal angle between 85° and 120°, and a small byssal notch (Allasinaz, 1972). According to these features, Entolioides belongs to the second group.

  • Mineralogy.—Bimineralic (Carter, Barrera, & Tevesz, 1998). See mineralogy for Entolium (see p. 105).

  • Superfamily KALENTEROIDEA Marwick, 1953

  • According to Z. Fang and Morris (1997) and Damborenea (2004), the classification of the superfamily Kalenteroidea Marwick, 1953, is modified with respect to Amler (1999); we consider the family Permophoridae Poel, 1959, as a synonym of Kalenteridae Marwick, 1953. Several genera assigned to this family are very similar to each other, both externally and internally (hinge details and muscle impressions) (Damborenea, 2004).

  • Family KALENTERIDAE Marwick, 1953
    (=Permophoridae Poel, 1959)
    Genus PERMOPHORUS Chavan, 1954, p. 200

  • nom. nov. pro Pleurophorus King, 1844, p. 313, non Mulsant, 1842, p. 312

  • Type species.—Arca costata Brown, 1844, p. 66.

  • Stratigraphic range.—Carboniferous (Mississippian)—Lower Triassic (Olenekian) (Hoare, Heaney, & Mapes, 1989; Newell & Boyd, 1999). Cox and others (1969) assigned it a Lower Carboniferous—Permian range. For a long time, it was regarded as an exclusively Paleozoic genus, but recently, it was also reported from the Triassic. We are only taking into account the Triassic record in Newell and Boyd (1999), since other records have some problems we cannot solve now. Newell and Boyd (1999) warned about the misunderstanding of the Permophorus hinge details in Cox and others (1969). Based on this interpretation, Waterhouse (1979b) described Lower Triassic specimens from New Zealand that were subsequently assigned to the Middle Triassic (H. J. Campbell, 1984). Although other species were reported from the Lower Triassic (see Newell & Boyd, 1999), they were based on poorly preserved material. In addition, Permophorus was also reported from the Upper Triassic (Rhaetian) by Ivimey-Cook and others (1999), but these authors pointed out that the assignment was doubtful, since they did not observe the hinge of their specimens. Skwarko (1967) referred his Carnian and Norian specimens from New Guinea to Permophorus? hastatus, but later, Skwarko (1983) designated this as type species of his new genus Somareoides Skwarko, 1983.

  • Paleogeographic distribution.—Circumpacific (Fig. 38). In our study interval, it was only known from the Circumpacific domain. Fraiser and Bottjer (2007a) also listed it from the Triassic of Italy, but they did not figure or describe the specimens.

  • Circumpacific domain; late Permian; Japan (Nakazawa & Newell, 1968; Hayami & Kase, 1977); Early Triassic; Olenekian of Utah, Wyoming, Idaho, and Montana (United States) (Newell & Boyd, 1999), ?Idaho (United States) (Ciriacks, 1963), western United States (Boyer, Bottjer, & Droser, 2004; Fraiser & Bottjer, 2007a).

  • Paleoautoecology.—B, Is, S, Endo-Un, Sed-SM; By-Sb. Permophorus had some characteristics that indicate a shallow burrowing habit. It had an equivalve, inequilateral, and elongated shell, with prosogyrous beaks, lunule, and escutcheon that, according to S. M. Stanley (1975), facilitates burial. No palliai sinus is observed, so if siphonate, siphons would have been very short. According to Quiroz-Barroso and Perrilliat (1998), Permophorus was an endobyssate bivalve, but none of the specimens described in the literature show a byssal notch or gape. However, S. M. Stanley (1972) noted that at least the type species had a reduced anterior part, which suggests the presence of a byssus.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 271). Outer shell layer: aragonite (fibrous-prismatic). Middle shell layer: aragonite (cross-lamellar). Inner shell layer: aragonite (homogeneous).

  • Genus CURIONIA Rossi Ronchetti
    in Rossi Ronchetti & Allasinaz, 1965, p. 366

  • Type species.—Myoconcha curionii Hauer, 1857, p. 561.

  • Stratigraphic range.—Lower Triassic (?)—Upper Triassic (Rhaetian) (Rossi Ronchetti & Allasinaz, 1965). Rossi Ronchetti (in Rossi Ronchetti & Allasinaz, 1965) proposed Curionia and assigned it a Triassic (Scythian—Rhaetian) range. When listing the included species, she first mentioned those that were contemporaneous with the type species (Carnian), and then the other Triassic species; so, in her list, the first recorded species is Carnian and the last is Rhaetian. Perhaps because of this arrangement, Cox and others (1969) considered the genus to be present only in the Late Triassic, or maybe they simply disagreed with the species listed by the author of the genus. We assign to Curionia the stratigraphic range given by its original authors.

  • Paleogeographic distribution.—Tethys (Fig. 38). Curionia was only known from the Tethys domain. It was reported from the Early Jurassic of Nevada (Laws, 1982), but Hallam and Wignall (2000) argued that Laws probably confused Curionia with Modiolus, which is very abundant in the area, since Curionia was a European genus that disappeared in the Late Triassic. However, Stiller and Chen (2006) reported it from the Anisian of China.

  • Tethys domain: Early Triassic: Olenekian of ?Bakony (Hungary) (Frech, 1907; Rossi Ronchetti & Allasinaz, 1965); Middle Triassic: Anisian of China (Stiller & Chen, 2006), Italy (Rossi Ronchetti & Allasinaz, 1965); Muschelkalk of Germany (Rossi Ronchetti & Allasinaz, 1965); Ladinian of Italy (Posenato, 2002); Late Triassic: Carnian of the Alps (Rossi Ronchetti & Allasinaz, 1965); Norian of Italy (Rossi Ronchetti & Allasinaz, 1965); Rhaetian of Italy (Stoppani, 1860—1865; Rossi Ronchetti & Allasinaz, 1965), Iran (Repin, 2001).

  • Paleoautoecology.—B, Is-Se, S, Endo-Un, Sed-SM; By-Sb. Like all Kalenteridae genera, the external morphology of Curionia indicates a shallow infaunal or semi-infaunal mode of life. By analogy with Modiolus, it could perhaps have been an endobyssate bivalve.

  • Mineralogy.—Aragonitic (Schneider & Carter, 2001). Outer shell layer: aragonite (prismatic). Middle shell layer: aragonite (crosslamellar). Inner shell layer: aragonite (prismatic).

  • Genus TRIAPHORUS Marwick, 1953, p. 69

  • Type species.—Pleurophorus zealandicusTrechmsxm, 1918, p. 212.

  • Stratigraphic range.—Upper Triassic (Carnian—Norian) (H. J. Campbell, 1984). Marwick (1953) proposed Triaphorus from Carnian deposits. Subsequently, Cox and others (1969) assigned it an Upper Triassic range. Grant-Mackie (1960) reported it from Otapirian (=Rhaetian) and Warepan (=Norian) of New Zealand, but he did not figure the specimens and based his record on a personal communication from J. D. Campbell. Moreover, H. J. Campbell (1984) mentioned the genus from the upper ?Carnian-Norian, but neither figured nor described the material, although he mentioned several references. Following H. J. Campbell (1984), we assign it a Carnian—Norian range.

  • Paleogeographic distribution.—Austral, Boreal, and Circumpacific (Fig. 38). Triaphorus was distributed in the Austral and Circumpacific domains and doubtfully in Boreal regions as well. When the specimens are not well preserved and the hinge is not seen, it is difficult to distinguish between Triaphorus and Kalentera (Damborenea, 2004). This latter genus had a bipolar distribution during the Jurassic, but during the Late Triassic, it was only known from the Austral domain. It is necessary to check if the Boreal records of Triaphorus can be confirmed and if the specimens show the diagnostic characters.

  • Austral domain: Late Triassic: Carnian of New Zealand (Trechmann, 1918; Marwick, 1953); Carnian—Norian of New Zealand and New Caledonia (H. J. Campbell, 1984).

  • Boreal domain: Late Triassic: northeastern Russia (Kiparisova, Bychkov, & Polubotko, 1966); Carnian of Primorie (Kiparisova, 1972).

  • Circumpacific domain: Late Triassic: Carnian of Japan (Kobayashi & Ichikawa, 1950; Hayami, 1975).

  • Paleoautoecology.—B, Is-Se, S, SM; Sb. Triaphorus is externally similar to Permophorus and Kalentera. It had a modioliform shell, and, in the genus diagnosis offered by Marwick (1953), the presence of a pedal muscle scar is pointed out. Since no palliai sinus and no evidence of byssate habit are listed, we assume that it was a shallow burrower belonging to the shallow infauna or semi-infauna (Grant-Mackie, 1960).

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 270). According to Carter (1990a), although the shell mineralogy of Triaphorus and other members of the family Kalenteridae is unknown, its mode of preservation suggests an original aragonitic mineralogy.

  • Figure 38.

    Paleogeographical distribution or Kalenteridae (Permophorus, Curionia, Triaphorus, Somareoides, Kalentera, Ouanouia, Weixiella). 1, Early Triassic; Middle Triassic; 3, Late Triassic—Early Jurassic.

    f38_01.jpg

    Genus SOMAREOIDES Skwarko, 1983, p. 67

  • Type species.—Permophorus? hastatus Skwarko, 1967, p. 66.

  • Remarks.—Skwarko (1967) tentatively included the species hastatus Skwarko, 1967, in Permophorus, as only external structures could be observed in his specimens. The discovery of new material with well-preserved hinge confirmed that this species does not belong to Permophorus nor to any previously known genus (Skwarko, 1983).

  • Stratigraphic range.—Upper Triassic (Carnian) (Skwarko, 1983). Although Skwarko (1967) assigned a Carnian—Norian range to the type species, when he proposed Somareoides (Skwarko, 1983), he noted that the most likely age was Carnian.

  • Paleogeographic distribution.—Southern Tethys (Fig. 38).

  • Tethys domain: Late Triassic: Carnian of Papua New Guinea (Australian province according to Damborenea, 2002b) (Skwarko, 1967,1983).

  • Paleoautoecology.—B, Se, S, Endo-Un, Sed-SM; Sb. According to Skwarko's (1983) description, Somareoides had an inequivalve and modioliform shell, with developed anterior part and elongated posterior one. With these characteristics, its mode of life should be similar to other family members. It was probably a semi-infaunal bivalve.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 270). See mineralogy for Triaphorus (p. 107).

  • Genus KALENTERA Marwick, 1953, p. 108

  • Type species.—Kalentera mackayi Marwick, 1953, p. 108.

  • Stratigraphic range.—Upper Triassic (Norian)—Lower Jurassic (Toarcian) (Grant-Mackie, 1960). Marwick (1953) proposed Kalentera and included two new species, K. mackayi from the Lower Jurassic and K. flemingi from the Temaikan (Bathonian). Later, Grant-Mackie (1960) indicated that the beds that Marwick (1953) referred to as Temaikan were Ururoan instead (= Pliensbachian-Toarcian), and he proposed another new species within the genus, K. marwicki from the Otapirian (=Rhaetian). He also mentioned the genus from Warepan (=Norian) as being associated with Monotis calvata Marwick, 1953. Cox and others (1969) assigned Kalentera a Lower Jurassic range and Sepkoski (2002) assigned it an Upper Triassic (upper Carnian)—Middle Jurassic (Bathonian) range, following Hallam (1977). Hallam mentioned the genus from the Middle Jurassic, but not in the Carnian. H. J. Campbell (1984) assigned it a Norian—Bathonian range. Following Grant-Mackie (1960), we assign it a Norian—Toarcian range.

  • Paleogeographic distribution.—Austral and Circumpacific (Fig. 38). Although originally thought to be endemic to the Austral domain, new records showed that Kalentera was endemic to the southern domain (Maorian Province) during the Late Triassic and had a bipolar distribution (at high latitudes) during the Early Jurassic (Damborenea, 2001, 2002b, 2004) (see also Triaphorus paleogeographic distribution, p. 107). Boreal records date from the Pliensbachian (Damborenea, 2004; Zakharov & others, 2006), and, therefore, they are not taken into account here. D. G. Taylor and Guex (2002) included their new species K. lawsi Taylor & Guex, 2002, from the Triassic—Jurassic boundary beds of Oregon in Kalentera, but this assignment is tentative, because their specimens did not show hinge details. Damborenea (2004) noticed that those specimens were previously allocated to Curionia sp. by Laws (1982), and, later, D. G. Taylor, Boelling, and Guex (2000) assigned them to Kalentera? sp. However, Hallam and Wignall (2000) considered that Laws's (1982) “Curionia” specimens could probably refer to Modiolus, a genus very abundant in the area. Laws (1982) did not figure the specimens, and those figured by D. G. Taylor and Guex (2002) are unconvincing.

  • Circumpacific domain: Early Jurassic: Sinemurian of northern Chile (Covacevich, Pérez, & Escobar, 1991).

  • Austral domain: Late Triassic: Norian—Rhaetian of New Zealand (Grant-Mackie, 1960; MacFarlan, 1998); Early Jurassic: Hettangian—Sinemurian ofNew Zealand (Marwick, 1953), Argentina (Damborenea, 2004).

  • Paleoautoecology.—B, Se-Is, S, SM; Sb. Kalentera shell morphology indicates that it was probably a shallow burrower that lived wholly or partly buried in the sediment (Grant-Mackie, 1960; H. J. Campbell, 1984; Damborenea, 2004). The inferred environment of the fossilbearing beds indicates that stability and type of substrate limited the distribution of this genus (Damborenea, 2004) in nearshore deposits. According to Grant-Mackie (1960), the absence of excavated galleries in the sediment and of a palliai sinus suggests Kalentera lacked siphons (or perhaps they were too short), and therefore it would have been a very shallow burrower.

  • Mineralogy.—Aragonitic (Carter, 1990a, p. 270; Damborenea, 2004). In Kalentera (or other members of the family Kalenteridae), the shell mineralogy is unknown, although, according to Carter (1990a), its mode of preservation suggests an original aragonitic mineralogy. Furthermore, Damborenea (2004, fig. 4b) showed a hexagonal dissolution pattern for one of her specimens, which can be interpreted as a relict aragonitic nacreous trace in the inner shell layer.

  • Genus OUAMOUIA H. J. Campbell, 1984, p. 158

  • Type species.—Ouamouia grantmackiei H. J. Campbell, 1984, p. 159.

  • Remarks.—H. J. Campbell (1984) included Ouamouia in the family Permophoridae (=Kalenteridae) and related it mainly to Permophorus and Kalentera. However, Damborenea (2004) argued that Ouamouia is quite different from Kalentera, and its massive hinge dentition and other characters indicate it was a cardiniid.

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (H. J. Campbell, 1984). This monospecific genus was described by H. J. Campbell (1984) from Norian—Rhaetian beds.

  • Paleogeographic distribution.—Austral (Fig. 38).

  • Austral domain: Late Triassic: Norian—Rhaetian of New Zealand and New Caledonia (H. J. Campbell, 1984).

  • Paleoautoecology.—B, Is, S, Endo-Un, Sed-SM; By-Sb. Ouamouia grantmackiei had a modioliform shell, undefined palliai sinus, lunule, and ornamented shell. These characteristics match well with a shallow burrower mode of life. Probably it lived buried near the surface and possessed short siphons (see H. J. Campbell, 1984, p. 162). Because it had a thick shell and a massive hinge, it probably lived in high-energy environments (H. J. Campbell, 1984). No structure suggesting it was a byssate bivalve is present, but its modioliform shape may indicate this life habit.

  • Mineralogy.—Aragonitic. There are no data about Ouamoia shell mineralogy or microstructure. The shell was probably entirely aragonitic.

  • Genus WEIXIELLA Guo & Chen in Guo, 1985, p. 187, 268

  • Type species.—Weixiella diana Guo & Chen in Guo, 1985, p. 187.

  • Remarks.—Guo and Chen (in Guo, 1985) included Weixiella in the family Pachycardiidae Cox, 1962, due its resemblance to Cardiniodes Kobayashi & Ichikawa, 1952, especially in hinge features. However, Hautmann (2001b) found more similarities with Permophorus Chavan, 1954, and included it in the family Permophoridae (=Kalenteridae), although he also indicated some resemblance to the family Unionidae Fleming, 1828. Z. Fang and others (2009) followed the original paper by Guo (1985) and referred it to the family Pachycardiidae.

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (Hautmann, 2001b). The genus was described from the Upper Triassic of Yunnan (China). Hautmann (2001b) reported it from the Norian—Rhaetian of Iran and also mentioned it from coeval beds in China, referring to the original description of the genus.

  • Paleogeographic distribution.—Tethys (Fig. 38).

  • Tethys domain: Late Triassic: Norian—Rhaetian of China (Guo & Chen in Guo, 1985; Hautmann, 2001b), Iran (Hautmann, 2001b).

  • Paleoautoecology.—B, Is, S, Endo-Un, Sed-SM; By-Sb. Weixiella was a suspensivorous shallow burrower (Hautmann, 2001b). The external morphology is not very different from the other members of the family Kalenteridae, but the anterior is more lobed. Although structures indicating the presence of byssus were not observed, it might have been endobyssate, as were other members of this family.

  • Mineralogy.—Aragonitic. There are no data about Weixiella shell structure. We assigned it aragonitic shell mineralogy, as in other members of the family Kalenteridae.

  • Family MYOCONCHIDAE Newell, 1957
    Genus MYOCONCHA J. de C. Sowerby, 1824, p. 103

  • Type species.—Myoconcha crassa J. de C. Sowerby, 1824, p. 103.

  • Stratigraphic range.—Upper Triassic (Rhaetian)—Upper Cretaceous (Maastrichtian) (Hodges, 2000). With the inclusion ofTriassic species previously assigned to Myoconcha into Curionia Rossi Ronchetti (in Rossi Ronchetti & Allasinaz, 1965, p. 366) and Pseudomyoconcha Rossi Ronchetti (in Rossi Ronchetti & Allasinaz, 1966, p. 1101), Myoconcha was restricted to Jurassic onward. Cox and others (1969) assigned it a Lower Jurassic—Upper Cretaceous range, with a doubtful record from the Permian. Even so, some authors maintained its range from the Upper Triassic. Hautmann (2001b) considered Pseudomyoconcha to be a subgenus of Myoconcha and mentioned it from the Norian and Rhaetian. Hodges (2000) assigned it an Upper Triassic—Upper Cretaceous range and doubtfully extended it to the Permian. Hodges (2000) reported Myoconcha (Myoconcha) psilonoti Quenstedt, 1856 in 1856—1858, from the Rhaetian of England, and it was also mentioned from the Rhaetian of the Apennines (Diener, 1923). Ivimey-Cook and others (1999) mentioned the same species from the Rhaetian of England, but the figured specimen does not show the hinge, a character critical to distinguish it from other Myoconchidae. Other authors (e.g., Zorn, 1971; Busse & Horn, 1978; Malinowskiej, 1979) mentioned Triassic species assigned to Myoconcha that were transferred to other genera by Rossi Ronchetti and Allasinaz (1965, 1966).

  • The Permian quotations appeared from the subjective synonymy proposed by Newell (1957), who considered Labayophorus Licharew, 1939, upper Permian genus of the Caucasus, as a junior synonym of Myoconcha. This seems to have been accepted with reservations by subsequent authors who indicated the doubtful presence of Myoconcha in the Permian. Rossi Ronchetti and Allasinaz (1966) noticed that the illustration of the right valve of Myoconcha, figured in Newell (1957) and prepared by Cox, is the only existing schematic representation of the right valves of Myoconcha. Labayophorus and Myoconcha are distinguished by the presence of one cardinal tooth in each valve in the former, while the latter has one on the right and two on the left valve. In addition, Rossi Ronchetti and Allasinaz (1966) listed some other differences that could separate the two genera, and they considered Labayophorus to be Paleozoic and Myoconcha to be Mesozoic, predominantly Jurassic. Some Permian records do not seem to be attributable to Myoconcha. Simões and Fittipaldi (1987) reported Myoconcha from the Permian, following Mendes (1944), who recorded a doubtful Myoconcha sp. from sediments originally dated as Triassic but later proved to be Permian (Simões & Fittipaldi, 1987). Later, Mendes (1945) reassigned these specimens to Naiadopsis lamellosus Mendes. Furthermore, Mendes (1944) noticed that Permian specimens attributed to Myoconcha are probably Modiolopsis. Another Permian record is found in Hayas aka (1967) from Japan, but the only available specimen is strongly deformed and incomplete, and its generic assignation is very doubtful.

  • Paleogeographic distribution.—Tethys and Austral (Fig. 39).

  • Tethys domain: Late Triassic: Rhaetian of England (Ivimey-Cook & others, 1999; Hodges, 2000); Early Jurassic: Hettangian—Sinemurian of England (Hodges, 2000; Hallam, 1987); Sinemurian of England (Liu, 1995), Turkey (M. A. Conti & Monari, 1991).

  • Austral domain; Early Jurassic; Hettangian—Sinemurian of Argentina (Damborenea & Manceñido, 2005b).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. According to S. M. Stanley (1972), most species belonging to this genus have a modioliform external appearance, have elongated and prosocline shells, with a reduced anterior part and broad byssal gape, indicating an endobyssate semi-infaunal mode of life, similar to Modiolus. Other authors agreed with the attribution of this mode of life (Damborenea in Damborenea & González-León, 1997; Hodges, 2000; Delvene, 2001).

  • Mineralogy.—Aragonitic (Morris, 1978; Z. Fang & Morris, 1997). According to Morris (1978), Myoconcha decorata (Münster, 1837, in Goldfuss, 1833—1841) had a homogeneous shell microstructure, but he noticed that the lack of a prismatic outer shell layer may be due to erosion of the shell. Carter (1990a) suggested that the shell should be reviewed to observe if there is cross-lamellar structure. Z. Fang and Morris (1997) found remains of cross-lamellar structure preserved in specimens of Myoconcha saemanni Loriol.

  • Figure 39.

    Paleogeographical distribution of Myoconchidae (Myoconcha, Pseudomyoconcha, Healeya). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f39_01.jpg

    Genus PSEUDOMYOCONCHA
    Rossi Ronchetti in Rossi Ronchetti & Allasinaz, 1966, p. 1101

  • Type species.—Myoconcha lombardica Hauer, 1857, p. 559.

  • Remarks.—Rossi Ronchetti (in Rossi Ronchetti & Allasinaz, 1966) transferred all Triassic species previously assigned to Myoconcha to Pseudomyoconcha, except for those she included in Curionia (see Rossi Ronchetti & Allasinaz, 1965). Some species were introduced in Pseudomyoconcha tentatively, because the hinge (a key character) was not observed. She separated these species into two groups: one containing the species that were consistent with the new genus diagnosis, and another with species that did not fit strictly there but were closer to Pseudomyoconcha than to Myoconcha. She noticed that the latter group probably could be recognized as a new taxon but could not see details of the hinge and muscle scars. Hautmann (2001b) argued that differences between Myoconcha and Pseudomyoconcha are very subtle and decided to keep the second as a subgenus of the first.

  • Stratigraphic range.—Middle Triassic (Ladinian)—Upper Triassic (Rhaetian) (Rossi Ronchetti & Allasinaz, 1966; Hautmann, 2001b). The range assigned by Rossi Ronchetti (in Rossi Ronchetti & Allasinaz, 1966), according to the species included in the new genus, was Ladinian—Norian. Cox and others (1969) assigned it the same stratigraphic range. The genus was extinguished in the Late Triassic (Hallam, 1981, 2002).

  • Paleogeographic distribution.—Tethys, Boreal, and Circumpacific (Fig. 39). Pseudomyoconcha was reported from the Late Triassic of China (Wen & others, 1976; Lu, 1981; Gou, 1993), but the specimens figured in those papers do not seem convincing. In none is the hinge shown, and the external morphology of the members of the families Myoconchidae and Permophoridae are similar. J. Chen (2003, p. 658, fig. 4.4.2) recorded it from the Anisian and throughout the Late Triassic in southern China, but he did not figure it or indicate the original data source. The presence of Pseudmnyoconcha in southern China is thus still doubtful.

  • Tethys domain; Middle Triassic; Ladinian of Hungary, Germany, and Italy (Rossi Ronchetti & Allasinaz, 1966); Late Triassic; Carnian of Italy (Rossi Ronchetti & Allasinaz, 1966), Germany (Linck, 1972), Slovenia and Yugoslavia (Jelen, 1988); Carnian—Norian of Hungary (Rossi Ronchetti & Allasinaz, 1966); Norian—Rhaetian of Iran (Hautmann, 2001b).

  • Circumpacific domain; Late Triassic; Carnian, ?Norian of Japan (Rossi Ronchetti & Allasinaz, 1966); Norian of western Carpathians (Kollarova & Kochanová, 1973).

  • Boreal domain; Late Triassic; Primorie (Kiparisova, 1972).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. According to the generic diagnosis by Rossi Ronchetti (in Rossi Ronchetti & Allasinaz, 1966), the Pseudomyoconcha shell is equivalve, strongly inequilateral, modioliform, and had a byssal notch. With these characteristics, it was most likely an endobyssate semi-infaunal bivalve.

  • Mineralogy.—Aragonitic (Rossi Ronchetti & Allasinaz, 1966; Carter, 1990a, p. 271). Carter (1990a) interpreted the data provided by Rossi Ronchetti and Allasinaz (1966) slightly differently. He identified a fibrous prismatic outer shell layer and a middle shell layer of cross-lamellar structure.

  • Genus HEALEYA Hautmann, 2001b, p. 108

  • Type species.—Modiolopsis gonoides Healey, 1908, p. 51.

  • Remarks.—Hautmann (2001b) proposed the genus Healeya within the subfamily Myoconchinae. Subsequently, Hautmann (2008) proposed a new family, Healeyidae, to include Healeya and other genera. Given the objections with this new family proposition, we consider Healeya in its original allocation (see discussion for the family Mysidiellidae Cox, 1964, p. 22).

  • Stratigraphic range.—Upper Triassic (Norian—Rhaetian) (Hautmann, 2001b, 2008). Healeya is a Upper Triassic monospecific genus. Hautmann (2001b) reported from the Norian—Rhaetian of Iran. The type species was originally described from the Rhaetian of Burma (India) by Healey (1908).

  • Paleogeographic distribution.—Tethys (Fig. 39). Apart from Iran and Burma, Hautmann (2001b) mentioned the possible occurrence of this genus from the Upper Triassic of Malaysia and Vietnam, due to the doubtful inclusion of two species recorded from that area, in the list of synonyms of the type species.

  • Tethys domain; Late Triassic; Norian—Rhaetian of Iran (Hautmann, 2001b); Rhaetian of Burma (India) (Healey, 1908).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Hautmann (2001b) found specimens in life position that corroborate what their morphology indicated, i.e., Healeya lived semi-infaunally and it was probably an endobyssate bivalve. In the anterior part of the shell, the muscle scar of probably a byssal retractor is observed; the byssus would have been strong and protruded from the anterior part of the shell (Hautmann, 2008).

  • Mineralogy.—Aragonitic (Hautmann, 2008). Although no studies of Healeya shell microstructure were performed, the type of recrystallization indicates an aragonitic mineralogy (Hautmann, 2008).

  • Family HIPPOPODIIDAE Cox in Cox and others, 1969
    Genus HIPPOPODIUM J. Sowerby, 1819, p. 91

  • Type species.—Hippopodium ponderosum J. Sowerby, 1819, p. 91.

  • Stratigraphic range.—Upper Triassic (?Rhaetian)—Upper Jurassic (Tithonian). Cox and others (1969) assigned it a Lower Jurassic range (Hettangian—Pliensbachian) and also considered it to be from the Upper Jurassic (Tithonian). However, Zapfe (1967) suggested the origin of Hippopodium in the Rhaetian of the Alps. Hallam and El Shaarawy (1982) also reported it from the Rhaetian of the Alpine region of northwestern Europe, but they did not figure or describe the specimens, nor did Hallam (1981), who quoted it from the Upper Triassic of western Tethys.

  • Paleogeographic distribution.—Western Tethys and Boreal (Fig. 40). Hippopodium was a characteristic genus of the Boreal domain during the Early Jurassic (Sinemurian and Pliensbachian) (Liu, 1995). This author included England in the Boreal domain during this time. This area was on the boundary between the Boreal and Tethys domains, depending on whether their definition is based on bivalves or ammonoids. Hallam (1977) mentioned it from the European province, and, previously, he stated that although it was present in the Tethys domain, records were always from the north (Hallam, 1972).

  • Tethys domain; Late Triassic; Rhaetian of the ?Alps (Zapfe, 1967); Early Jurassic; Hettangian-Sinemurian of Germany (Arp, 2007).

  • Boreal domain; Early Jurassic; Sinemurian of England (Liu, 1995).

  • Paleoautoecology.—B, Se, S, Endo, Sed; By. Hippopodium had a lobate anterior part, thick shell, prosogyrous umbones, and a palliai line without sinus. No structures indicating the presence of byssus were observed. It probably lived semiburied.

  • Mineralogy.—Aragonitic (Morris, 1978; Carter, 1990a; Z. Fang & Morris, 1997). The species H. ovale Moore had a homogeneous microstructure in the whole shell (Morris, 1978). Carter (1990a) noticed the need for more careful studies of the shell of this species to exclude the presence of cross-lamellar microstructure. Z. Fang and Morris (1997, p. 57) found, in a H. ponderosum Sowerby specimen, “patches of ill preserved but distinct crossed-lamellar structure;” but they did not find any trace of cross-lamellar structure in H. ovale, while in other species reported from the same beds, this microstructure was perfectly preserved.

  • Figure 40.

    Paleogeographical distribution of Hippopodiidae (Hippopodium). Late Triassic—Early Jurassic.

    f40_01.jpg

    Superfamily TRIGONIOIDEA Lamarck, 1819

  • For the location of genera in the Trigonioidea families, we mainly follow Cox and others (1969), except for families Minetrigoniidae and Myophoriidae, for which we follow Fleming (1987).

  • Family TRIGONIIDAE Lamarck, 1819
    Genus TRIGONIA Bruguière, 1789 in 1789—1792, p. xiv

  • Type species.—Venus sulcata Hermann, 1781, p. 127.

  • Stratigraphic range.—Middle Triassic (Anisian)—Upper Cretaceous (Cenomanian) (H. A. Leanza, 1993). Cox and others (1969) assigned it a Middle Triassic—Upper Cretaceous range. The Anisian species Trigonia tabacoensis Barthel, 1958, is the earliest known species in this genus (Fleming, 1964, 1987; Pérez & Reyes, 1991; Francis & Hallam, 2003). It is difficult to establish the top of the range because, in recent years, many Cretaceous genera related to Trigonia were proposed, and many of them were based on type species previously referred to Trigonia. Of the subgenera considered by Cox and others (1969), only T. (Trigonia) is included here, since Frenguelliella A. F. Leanza, 1942, is here regarded as a distinct genus, with Kumatrigonia Tamura, 1959, p. 213, as its subgenus. We follow Cox and others (1969) for the top of the range (Cenomanian). T. (Heslingtonia) Fleming, 1987, p. 22, is also considered as a subgenus within Trigonia in our study interval.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 41). Its distribution is limited during the Triassic to Barthel's (1958) record from the Anisian. Pérez and Reyes (1991) also reported Trigonia from the Upper Triassic and the Early Jurassic of Peru. In Europe, the family Trigoniidae appears in the Toarcian (Francis & Hallam, 2003). However, Hautmann (2001b) reported the type species of his new subgenus, Trigonia (Modestella) zlambachensis Haas, 1909, from the Alpine Rhaetian. Previously, this was reported by Fallahi, Gruber, and Tichy (1983) and Fleming (1987). Moreover, Hautmann (2001b) also quoted this species from the Norian of Vietnam and the Rhaetian of Burma (Malaysia).

  • Tethys domain; Late Triassic; Norian of Vietnam (Vu Khuc & Huyen, 1998; Hautmann, 2001b; Guo, 1985); Norian—Rhaetian of Iran (Fallahi, Gruber, & Tichy, 1983; Hautmann, 2001b).

  • Circumpacific domain; Middle Triassic; Anisian of Chile (Barthel, 1958); Late Triassic; Norian of Peru (Pérez & Reyes, 1991); Early Jurassic; Hettangian of Japan (Kobayashi & Kaseno, 1947; Hayami, 1975; Sato & Westermann, 1991); Hettangian—Sinemurian of Peru (Ishikawa & others, 1983; Pérez & Reyes, 1991); Sinemurian of Nevada (United States) (Poulton, 1979).

  • Austral domain; Middle Triassic; Anisian—Ladinian of New Zealand (Fleming, 1964, 1987).

  • Paleoautoecology.—B, Is, S, FM; Sb. Many authors have dealt with the mode of life of trigoniids (Tevesz, 1975; S. M. Stanley, 1977, 1978; Kelly, 1995b; Villamil, Kauffman, & Leanza, 1998; Francis & Hallam, 2003). Currently, there is only one genus, Neotrigonia, that lives in Australian waters (Beesley, Ross, & Wells, 1998). Neotrigonia is infaunal, filtering, and a nonsiphonate, fast, shallow-burrowing bivalve, which lives partially buried near the surface of the sediment (Tevesz, 1975). Mesozoic trigoniids probably had this same way of life, by analogy with Neotrigonia. S. M. Stanley (1969, 1970) showed that prosogyrous umbos helped burrowing, but the trigoniids have mostly opisthogyrous or orthogyrous umbos (S. M. Stanley, 1977). However, the external morphology, the varied ornamentation, the strong foot, and the complex hinge teeth are adapted to this mode of life (S. M. Stanley, 1977). Thus, the life position of species of this group is interpreted as being similar to Neotrigonia, with the posterior part near the sediment surface. In many instances, the presence of epibionts on the posterior part was observed, adding to the assumption that some species lived with this part exposed, in a semi-infaunal position (Villamil, Kauffman, & Leanza, 1998). However, no epibionts were observed on the Triassic genera, perhaps due to their small size (as compared with Cretaceous forms). Cretaceous species are larger and tend to have had a more sedentary mode of life (Kelly, 1995b).

  • We assign an infaunal shallow-burrowing mode of life to all members of the superfamily, although some may live with the posterior part slightly exposed. For more information about the mode of life of this interesting group of burrowers, see Tevesz (1975), S. M. Stanley (1977, 1978), Kelly (1995b), Villamil, Kauffman, and Leanza (1998), or Francis and Hallam (2003), among others.

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). The shells of all members of the superfamily Trigonioidea probably were entirely aragonitic, with a prismatic outer shell layer and a nacreous inner shell layer, as in the living species of Neotrigonia (J. D. Taylor, Kennedy, & Hall, 1969; Newell & Boyd, 1975).

  • Figure 41.

    Paleogeographical distribution of Trigoniidae (Trigonia, Praegonia, Prorotrigonia, Prosogyrotrigonia, Geratrigonia, Vaugonia, Kyushutrigonia, Acanomyophoria, Jaworskiella, Guineana, Frenguelliella). 1, Middle Triassic; 2, Late Triassic—Early Jurassic.

    f41_01.jpg

    Genus PRAEGONIA Fleming, 1962, p. 2

  • Type species.—Praegonia coombsi Fleming, 1962, p. 2.

  • Stratigraphic range.—Middle Triassic (Ladinian). Fleming (1962) proposed Praegonia from the Ladinian of New Zealand. It was only recorded from that time and area (Fleming, 1964, 1987; Cox & others, 1969).

  • Paleogeographic distribution.—Austral (Fig. 41). Praegonia is monospecific and endemic to the Austral domain.

  • Austral domain: Middle Triassic: Ladinian of New Zealand (Fleming, 1962, 1964, 1987).

  • Paleoautoecology.—B, Is, S, FM; Sb. See discussion under Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Praegonia shell microstructure. See discussion under Trigonia (p. 113).

  • Genus PROROTRIGONIA Cox, 1952, p. 57

  • Type species.—Trigonia seranensis Krumbeck, 1923a, p. 211.

  • Stratigraphic range.—Upper Triassic (Norian) (Kutassy, 1931). Cox (1952) erected Prorotrigonia and reported it from the Upper Triassic. Cox and others (1969) assigned it an Upper Triassic range. Krumbeck (1923a) described the type species from the Norian of Seram (Indonesia).

  • Paleogeographic distribution.—Tethys (Fig. 41). Hautmann (2001b) mentioned it from the Himalayas, as well as from southern Indonesia, but he did not refer to the original source. In addition, Tamura and Nishimura (1994) reported Prorotrigonia sp. from the Upper Triassic of Japan, but the figure of their specimen is of poor quality and it cannot be assigned with certainty to the genus. In fact, later, Tamura (1996) doubtfully recorded it as Prorotrigonia (?) sp. from the Upper Triassic of Japan.

  • Tethys domain: Late Triassic: Norian of Seram (Indonesia) (Krumbeck, 1923aSepmSepm; Cox, 1952).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Prorotrigonia shell microstructure. See discussion under Trigonia (p. 113).

  • Genus PROSOGYROTRIGONIA Krumbeck, 1924, p. 244

  • Type species.—Trigonia (Prosogyrotrigonia) timorensis Krumbeck, 1924, p. 245.

  • Stratigraphic range.—Upper Triassic (Norian)—Lower Jurassic (Sinemurian) (Hayami, 1975; Hautmann, 2001b). Cox and others (1969) assigned it an Upper Triassic range. Subsequent records extended the stratigraphic range of this genus to the Lower Jurassic (Hayami, 1975).

  • Paleogeographic distribution.—Tethys and Circumpacific (Fig. 41). Prosogyrotrigonia was also mentioned (Prosogyrotrigonia? sp.) from the Hettangian of northern Yukon (Canada) (Frebold & Poulton, 1977; Poulton, 1979), and new species were described from the Hettangian—Sinemurian of Chile (Pérez & others, 2008). It was also reported from Tibet (Kobayashi & Tamura, 1983a; Hautmann, 2001b), but these papers did not indicate the original source reference.

  • Tethys domain: Late Triassic: Norian—Rhaetian of Iran (Fallahi, Gruber, & Tichy, 1983; Hautmann, 2001b), Yunnan (China) (Guo, 1985); Rhaetian ofTimor (Indonesia) (Krumbeck, 1924; Kobayashi & Mori, 1954a).

  • Circumpacific domain: Early Jurassic: Hettangian—Sinemurian of Chile (Pérez & others, 2008); Sinemurian of Japan (Yehara, 1921; Kobayashi & Mori, 1954a; Hayami, 1975; Sato & Westermann, 1991), Sonora (Mexico) (Scholz, Aberhan, & González-León, 2008).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Prosogyrotrigonia shell microstructure. See discussion under Trigonia (p. 113).

  • Genus GERATRIGONIA Kobayashi in Kobayashi & Mori, 1954a, p. 171

  • Type species.—Trigonia hosourensis Yokoyama, 1904, p. 11.

  • Stratigraphic range.—Lower Jurassic (Hettangian—Toarcian) (Hayami, 1975). Cox and others (1969) assigned it a Lower Jurassic (lower Lower Jurassic) range, but Geratrigonia had been reported from the Toarcian (Kobayashi, 1957). The genus was quite common in the Hettangian of Japan (Hayami, 1959, 1975).

  • Paleogeographic distribution.—Circumpacific (Fig. 41). Although we consider Geratrigonia to be a Japanese endemic genus, it was also mentioned from South America (Pérez & Reyes, 1991), specifically the species Trigonia (Geratrigonia) kurumensis Kobayashi, 1954, from the Bata Formation (Colombia), then dated as Lower Jurassic. The specimens were later reassigned to Vaugonia niranohamensis santamariae Geyer, 1973, and, moreover, the Bata Formation was redated as Cretaceous (Etayo Serna & others, 2003).

  • Circumpacific domain: Early Jurassic: Hettangian of Japan (Kobayashi & Mori, 1954a; Hayami, 1959, 1975; Sato & Westermann, 1991; Sugawara & Kondo, 2004; Kondo & others, 2006).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Geratrigonia shell microstructure. See discussion under Trigonia (p. 113).

  • Genus VAUGONIA Crickmay 1930a, p. 53

  • Type species.—Vaugonia veronica Crickmay, 1930a, p. 53.

  • Stratigraphic range.—Lower Jurassic (Hettangian)—Upper Jurassic (Oxfordian) (Hayami, 1975). Crickmay (1932) mentioned Vaugonia from the Middle Jurassic. Subsequently, Kobayashi and Mori (1954b) proposed the new subgenus Hijitrigonia Kobayashi, 1954, from the Jurassic of Japan and indicated that Vaugonia had its origin during the Hettangian in Japan, and later it had a cosmopolitan distribution, probably extending to the Early Cretaceous. Cox and others (1969) considered V. (Hijitrigonia) as a junior synonym of V. (Vaugonia) and assigned a Jurassic range to the genus, including two subgenera: V. (Vaugonia) and V. (Orthotrigonia) Cox, 1952. No evidence of Vaugonia is found after the Jurassic. The youngest record is Oxfordian (Hayami, 1975).

  • Paleogeographic distribution.—Circumpacific (Fig. 41). Vaugonia originated in Japan during the Hettangian, and later it extended to the rest of the world. However, Francis and Hallam (2003) assumed a South American origin during the Sinemurian. Although during our study interval it was only recorded from the Circumpacific domain, since Pliensbachian times and throughout the Middle Jurassic, it had a cosmopolitan distribution (Fleming, 1964, 1987; Hallam, 1976; Poulton, 1976, 1979, 1991; Ishikawa & others, 1983; Pugaczewska, 1986; H. A. Leanza & Garate Zubillaga, 1987; H. A. Leanza, 1993; H. J. Campbell & Grant-Mackie, 1995; Kelly, 1995a).

  • Circumpacific domain: Early Jurassic: Hettangian—Sinemurian of Japan (Kobayashi & Mori, 1954b; Hayami, 1975; Sato & Westermann, 1991; Sugawara & Kondo, 2004); Sinemurian of Nevada (United States) (Poulton, 1979), Peru (Pérez & Reyes, 1991), Chile (Pérez & others, 2008).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia.

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Vaugonia shell microstructure. See discussion under Trigonia (p. 113).

  • Genus KYUSHUTRIGONIA
    Tamura & Nishimura, 1994, p. 15

  • Type species.—Kyushutrigonia hachibarensis Tamura & Nishimura, 1994, p. 18.

  • Stratigraphic range.—Upper Triassic (Carnian—Norian) (Tamura & Nishimura, 1994; see Onoue & Tanaka, 2005). Kyushutrigonia was proposed by Tamura and Nishimura (1994) from Japan (Sambosan Terrane). They indicated it was recorded in the Upper Triassic, but they did not provide the exact age of the association. Onoue and Tanaka (2005) reported an association from the same locality, with bivalves in common, and assigned it a Carnian—Norian age.

  • Paleogeographic distribution.—Circumpacific (Fig. 41).

  • Circumpacific domain: Late Triassic: Japan (Tamura & Nishimura, 1994; Tamura, 1996).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia.

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Kyushutrigonia shell microstructure. See discussion under Trigonia (p. 113).

  • Genus ACANOMYPHORIA Guo, 1985, p. 203, 269

  • Type species.—Acanomyphoria tuberose Guo, 1985, p. 203.

  • Remarks.—Sichuantrigonia Gou, 1993, was placed in synonymy with Acanomyophoria by Z. Fang and others (2009).

  • Stratigraphic range.—Upper Triassic (Carnian) (Guo, 1985). Guo (1985) proposed Acanomyphoria from Carnian beds of the Weiyuanjiang Formation of Guanfangnabang in Yunnan (China). Gou (1993) proposed Sichuantrigonia for material from the upper member of Hanwang Formation of Maan tang area in Jiangyou, Sichuan (China), which was dated as Carnian.

  • Paleogeographic distribution.—Eastern Tethys (Fig. 41).

  • Tethys domain: Late Triassic: Carnian of southwestern China (Guo, 1985; Gou, 1993).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Acanomyphoria shell microstructure. See discussion under Trigonia (p. 113).

  • Genus JAWORSKIELLA A. F. Leanza, 1942, p. 144, 166

  • Type species.—Trigonia burckhardti Jaworski, 1914, p. 299.

  • Remarks.—Although A. F. Leanza (1942) proposed it as a subgenus of Trigonia, Cox and others (1969) and subsequent authors regarded Jaworskiella as a separate genus. Later, Reyes and Pérez (1980) proposed a new subgenus, Quadratojaworskiella Reyes & Pérez, 1980, and subsequently raised it to generic rank (Pérez & others, 2008).

  • Stratigraphic range.—Lower Jurassic (Hettangian—Pliensbachian) (H. A. Leanza, 1993; Pérez & others, 2008). Cox and others (1969) assigned it a Lower Jurassic (middle Liassic)—Upper Jurassic range, but we only found it recorded from the Lower Jurassic. Poulton (1979) already doubted that the genus was present in the Upper Jurassic, and H. A. Leanza (1993) restricted its range to the Lower Jurassic. It is especially abundant during the Pliensbachian (A. F. Leanza, 1942; H. A. Leanza, 1993; Poulton, 1979; H. A. Leanza & Garate Zubiliaga, 1987).

  • Paleogeographic distribution.—Circumpacific and Austral (Fig. 41).

  • Circumpacific domain: Early Jurassic: Hettangian—Sinemurian of Chile (Pérez & Reyes, 1991; Pérez & others, 2008); Sinemurian of Nevada (United States) (Poulton, 1979).

  • Austral domain: Early Jurassic: Sinemurian of Argentina (Pérez & Reyes, 1991; Damborenea & Manceñido, 2005b).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia.

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Jaworskiella shell microstructure. See discussion under Trigonia (p. 113).

  • Genus GUINEANA Skwarko, 1967, p. 59

  • Type species.—Guineana jimiensis Skwarko, 1967, p. 60.

  • Stratigraphic range.—Upper Triassic (Carnian—Norian) (Skwarko, 1967). When Skwarko (1967) proposed Guineana, he tentatively included in this genus other species distributed throughout the Norian and Rhaetian of western Europe, Asia, and Nevada. We are not taking them into account, as Skwarko simply indicated they were externally similar, but he did not study the hinge details of any of them.

  • Paleogeographic distribution.—Austral (Fig. 41). According to Damborenea (2002b), Guineana was endemic to the Australian province of the South Pacific domain.

  • Austral domain: Late Triassic: Carnian—Norian of New Guinea (Skwarko, 1967).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Guineana shell microstructure. See discussion under Trigonia (p. 113).

  • Genus FRENGUELLIELLA A. F. Leanza, 1942, p. 164

  • Type species.—Trigonia inexpectata Jaworski, 1915, p. 377.

  • Remarks.—A. F. Leanza (1942) proposed Frenguelliella as a subgenus of Trigonia, and this status was maintained by Cox and others (1969). Poulton (1979) decided to separate it from Trigonia and considered it to be a different genus due to the absence of radial ribs in the area. Furthermore, this author regarded Kumatrigonia Tamura, 1959, as a subgenus of Frenguelliella, as it was originally proposed. Cox and others (1969) considered Kumatrigonia as a subgenus of Trigonia. We follow Poulton (1979).

  • Stratigraphic range.—Upper Triassic (Carnian)—Middle Jurassic (Bajocian) (Hayami, 1975; H. A. Leanza, 1996). Cox and others (1969) assigned a Jurassic—Upper Cretaceous and Upper Triassic range to Trigonia (Frenguelliella) and Trigonia (Kumatrigonia), respectively. The last refers to Frenguelliella (Kumatrigonia) tanourensis Tamura, 1959, from the Carnian of Japan (Hayami, 1975). Frenguelliella was well distributed during the Jurassic, especially in the Pliensbachian (A. F. Leanza, 1942; Poulton, 1979; Ishikawa & others, 1983; H. A. Leanza & Garate Zubillaga, 1987; Pérez & Reyes, 1991; H. A. Leanza, 1993; Kelly, 1995a; Liu, 1995), but, although it was also recorded from the Upper Cretaceous in several papers (Cox & others, 1969; Poulton 1979; H. A. Leanza, 1993), we did not locate any species from deposits of that age. H. A. Leanza (1996) indicated that Frenguelliella was extinct by the Middle Jurassic (Bajocian), and its last species was F. perezreyesi H. A. Leanza 1993.

  • Paleogeographic distribution.—Circumpacific and Austral (Fig. 41). Although Cox and others (1969) considered it to be a cosmopolitan genus, the genus is primarily distributed on the Paleopacific margins. Pérez and Reyes (1991) recorded its presence in Europe, but no record from this area was found.

  • Circumpacific domain; Late Triassic; Carnian of Japan (Hayami, 1975); Norian of ?Oregon (United States) (Newton in Newton & others, 1987); Early Jurassic: Hettangian—Sinemurian of Texas (United States) (Liu, 1995); Sinemurian of northern Canada and Nevada (United States) (Poulton, 1979), Sonora (Mexico) (Scholz, Aberhan, & Gonzalez-León, 2008), Peru (Pérez & Reyes, 1991), Chile (Pérez & others, 2008).

  • Austral domain; Early Jurassic; Sinemurian of Argentina (H. A. Leanza, 1993, 1996; Damborenea, 1996a; Damborenea & Manceñido, 2005b; Damborenea & Lanés, 2007).

  • Paleoautoecology.—B, Is, S, FM; Sb. See mode of life for Trigonia (p. 113).

  • Mineralogy.—Aragonitic (J. D. Taylor, Kennedy, & Hall, 1969). No details are known about Frenguelliella shell microstructure. See discussion under Trigonia (p. 113).

  • Figure 42.

    Paleogeographical distribution of Costatoriidae (Costatoria). 1, late Permian-Early Triassic; 2, Middle Triassic; 3, Late Triassic—Early Jurassic.

    f42_01.jpg

    Family COSTATORIIDAE Newell & Boyd, 1995
    Genus COSTATORIA Waagen, 1907, p. 149

  • Type species.—Donax costata Zenker, 1833, p. 55.

  • Stratigraphic range.—upper Permian—Upper Triassic (Rhaetian) (Nakazawa & Newell, 1968; Hautmann, 2001b). Cox and others (1969) reported it from lower Permian ofTexas and Wyoming, from the upper Permian of Japan, and assigned it a Triassic cosmopolitan distribution. The lower Permian records are from Ciriacks (1963), with Costatoria sexraditata (Branson, 1930), which is the type species of Procostatoria Newell & Boyd, 1975. The genus is recorded from the upper Permian, with the species C. katsurensis Nakazawa, 1967 (Nakazawa & Newell, 1968; Hayami & Kase, 1977) and C. kobayasii (Kambe, 1957) (Nakazawa, 1960; Hayami, 1975; Hayami & Kase, 1977). Throughout the Triassic, it was recorded from various localities, from the Lower Triassic (Broglio-Loriga & Posenato, 1986) to the Rhaetian (Hautmann, 2001b). Many different species were recorded from the Tethys domain, sometimes based on biostratigraphic criteria; a revision and an evolutionary analysis of the group would be most interesting.

  • Paleogeographic distribution.—Tethys, Circumpacific, and Austral (Fig. 42). Although Cox and others (1969) regarded Costatoria as cosmopolitan during the Triassic, we did not find records from the Boreal domain.

  • Tethys domain; Early Triassic; Olenekian of Italy (Neri & Posenato, 1985; Broglio-Loriga & Posenato, 1986; Neri, Pasini, & Posenato, 1986; Posenato, 1989; Broglio-Loriga & others, 1990; Fraiser & Bottjer, 2007a); Middle Triassic; Germany (Hagdorn & Simon, 1985; Mahler & Sell, 1991), Poland (Senkowiczowa, 1985), Malaysia (Kobayashi & Tamura, 1968b); Anisian of southern China (Sha, Chen, & Qi, 1990; Tong & Liu, 2000; Komatsu, Chen, & others, 2004), Hungary (Szente, 1997), northern Vietnam (Komatsu, Huyen, & Huu, 2010); Ladinian of I