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Small, stemmed frond fossils are common in Ediacaran-aged strata (ca. 565 Ma) at Mistaken Point, Newfoundland, and many of them have previously been informally referred to as ‘dusters,’ but due to their small size and consequent relatively poor preservation, they have not yet been described taxonomically. Two new genera are herein defined on the basis of their unique constructions: the mop-like rangeomorph Plumeropriscum hofmanni new genus new species, and a flabellate, lobate frond Broccoliforma alta new genus new species. Plumeropriscumhofmanni n. gen., n. sp. has a three-dimensional petalodium structure with numerous primary branches attached at the base of the petalodium rather than at a central axis. Broccoliforma alta n. gen., n. sp. lacks visible branching, and instead has a lobate morphology with a petalodium that is at least superficially similar to the ivesheadiomorph Blackbrookia. Several other previously described taxa had also been included under the umbrella of ‘dusters.’ Collectively, these taxa show that the low epibenthic tier that small fronds occupied was more diverse than previously realized, with multiple taxa converging on the stemmed, small-frond body plan.
Three genera of gastropods described from the Lower Devonian Rockhouse Formation of Hardin County, Tennessee, currently are considered to be junior subjective synonyms of Platyceras (Visitator) Perner, 1911. Evaluation of the type specimens of these genera as well as types of two other gastropods from the same formation reveals the following: Platyostoma quadrangulare (Dunbar, 1920) is the only platyceratid gastropod among them; Saffordella tennessensisDunbar, 1920 has a selenizone above midwhorl so it is an eotomarioidean belonging to the Gosseletinidae; Aulopea nelsoniDunbar, 1920 and the lectotype of Distemnostoma princepsDunbar, 1920 each has a broad subsutural sinus on the upper whorl surface similar to the Omphalotrochidae, as well as a basal sinus similar to certain primitive caenogastropods, so their systematic position is uncertain; I consider Holopea planidorsataDunbar, 1920 to be a juvenile specimen of D. princeps; the fragmentary paralectotype of D. princeps possibly represents a gerontic form of Distemnostoma curtumDunbar, 1920, which possesses a well-developed selenizone on an upwardly projecting shoulder at the edge of the upper whorl surface. Because D. curtum appears to be unrelated to D. princeps, the genotype of Distemnostoma, I propose the new generic name Omocordella for D. curtum. The new family Micromphalidae is erected to include Ordovician SlehoferiaRohr and Fryda, 2001, lower Carboniferous MicromphalusKnight, 1945, and Omocordella n. gen.
The Campanian rudist fauna identified from the localities Playa Panamá, Santa Rosa National Park, Colorado de Abangares, and Bolsón in Guanacaste Province, Costa Rica, is composed of the antillocaprinids Antillocaprina sp. aff. A. suboccidentalisChubb, 1967, Antillocaprina sp. and Antillocaprinidae indet.; the multiplefold hippuritids Barrettia moniliferaWoodward, 1862, Parastroma trechmanniChubb, 1967, and cf. Whitfieldiella gigas (Chubb, 1955); the plagioptychids Plagioptychus trechmanni Chubb, 1956, Plagioptychus sp. cf. P. zansi Chubb, 1956, Mitrocaprina costaricaensis new species, Mitrocaprina multicanaliculata Chubb, 1956, and Plagioptychidae indet.; and the radiolitids Radiolites sp. aff. R. multicostata (Adkins, 1930), Alencasterites new genus mooretownensis (Trechmann, 1924), Bournonia? tetrahedron (Chubb, 1967), Chiapasella sp., Guanacastea costaricaensis new genus new species, cf. Potosites sp. aff. P. tristantorresi Alencáster and Pons in Pons et al., 2010, and aff. Thyrastylon sp. Although some differences in rudist diversity and sedimentary setting were observed among localities, most species indicate the same age for all occurrences, which correspond to the Campanian, probably mid-Campanian. Radiolitid specimens appear better preserved than those of other taxa and are thus discussed more in detail. Both the number of radiolitid genera exclusively known from the New World, and reasonable doubts about the correct attribution of some New World species to Old World genera, indicate important differences between rudist faunas at both sides of the Atlantic (Mediterranean and American Tethys, respectively) during the Late Cretaceous.
Paleozoic echinoids are exceptionally rare, and little is known of their paleoenvironmental distribution. The echinoid fauna of the Fort Payne Formation (Late Osagean, Early Viséan) of south-central Kentucky is documented. Four genera, ?Archaeocidaris, Lepidocidaris, ?Lepidesthes, and an unidentified lepidocentrid, were recovered and represent three different families. This fauna, and their associated paleoenvironments, give important new insights into the facies distribution of Paleozoic echinoids and the taphonomic biases that affect this distribution. Lepidocidaris is known from the green shale facies, which comprises the core of Fort Payne's carbonate buildups. ?Archaeocidaris and the lepidocentrid are known from the wackestone buildups and crinoidal packstone buildups. ?Lepidesthes is also known from crinoidal packstone and wackestone buildups, which argues against a semi-infaunal life mode for this taxon. All relatively semiarticulated echinoids were known from autochthonous facies, whereas the only echinoids from the allochthonous facies were disarticulated hemipyramids. Furthermore, deeper-water carbonate buildups were apparently capable of supporting diverse echinoid faunas during the Viséan.
The Upper Cretaceous “redbeds” of the lower Tremp Formation (South-Central Pyrenees, Spain) contains an ichnofauna consisting of Taenidium barretti, Taenidium bowni, Loloichnus isp., Arenicolites isp., Planolites isp., and Palaeophycus isp. This ichnofauna occurs in deposits formed in tide-influenced meander loops and their associated overbank mudflats. Evaluation of the taphonomic controls on the Tremp ichnofauna shows that (1) two morphotypes of Taenidium barretti are controlled by the substrate consistence, (2) Arenicolites may be enlarged by erosion processes, and (3) Taenidium barretti and Planolites isp. are not the same ichnotaxa showing different types of preservation. The meniscate fill in Taenidium barretti suggests that this structure was produced by deposit feeders. The Tremp ichnofauna is grouped into two trace-fossil assemblages, a depauperate subaquatic monospecific Planolites suite and an assemblage representing the Scoyenia Ichnofacies. Trace-fossil distribution reflects paleoenvironmental changes in the meandering channels along the stratigraphic section with the Planolites suite in the lowermost part of the lower interval and the Scoyenia Ichnofacies in the middle and upper intervals. The lowermost suite may be likely formed seaward of the maximum salinity limit, under extreme brackish-water conditions, whereas the Scoyenia Ichnofacies records a freshwater assemblage that was formed landward of the maximum salinity limit, reflecting deltaic progradation.
Continental deposits of the Early Jurassic East Berlin Formation in Holyoke, Massachusetts, have yielded an exceptional occurrence of the ichnogenus Treptichnus. Here, burrows are preserved in full relief within thin mud laminae between layers of fine-grained, cross-bedded sandstone. We studied these burrows to evaluate whether earlier explanations of burrow morphology are applicable to all Treptichnus. Our research focused on three questions. (1) Do the Holyoke Treptichnus have significant vertical relief? (2) Does the lack of projections in some of the Holyoke Treptichnus result from stratinomic sectioning through the bottom of the burrow? (3) Do expanded, bulbous ends of burrow segments result from sediment compaction? While addressing these questions, the Holyoke fossils were compared to syntype and topotype material of Treptichnus from the Carboniferous of Indiana. The Holyoke Treptichnus did not exhibit significant vertical relief, and the presence and absence of projections is explained by the positioning of new segments at different points along older ones. The bulbous ends of burrow segments resulted from trace-maker behavior, not sediment compaction. Drawing on the analysis of the Holyoke material, a new reconstruction is proposed that presents continental Treptichnus as a shallow mole-tunnel-like burrow produced just below the sediment surface. This reconstruction is consistent with the morphology of Recent Treptichnus-like burrows produced by fly (dipteran) larvae, which are considered the most likely makers of the Holyoke Treptichnus.
Tiny sinuous trace fossils have been found within probable gut contents of an exceptionally preserved specimen of a hadrosaurid dinosaur, Brachylophosaurus canadensis, from the Judith River Formation of Montana. Approximately 280 examples of the trace fossils were observed in 19 samples of gut region material. The tubular structures typically are about 0.3 mm across. Many have thin calcareous linings or layers, and some exhibit fine surficial striae. At least two dozen of these trace fossils share walls with adjacent tubular traces, and this association can extend for several millimeters. While the trace fossils share some characteristics with fine rhizoliths, these features are most consistent with tiny burrows, or possibly body impressions, of worms (vermiform organisms) of uncertain biologic affinity. Such trace fossils have not been reported previously, and herein described as Parvitubulites striatus n. gen. n. sp. Either autochthonous (parasites) or allochthonous (scavengers) worms may have created the trace fossils, but taphonomic factors suggest that autochthonous burrowers are more likely. Several lines of evidence, such as constant diameters and matching directional changes, suggest that the paired trace fossils were made by two individuals moving at the same time, which implies sustained intraspecific contact. Parvitubulites striatus provides a rare record of interactions between terrestrial, meiofaunal-sized, soft-bodied invertebrates and a dinosaur carcass. The evidence that the worms may have parasitized a living hadrosaur and subsequently left traces of intraspecific behavior between individual worms adds unique information to our understanding of Mesozoic trophic interactions.
Fossil catostomids were very rare prior to the Eocene. After the Eocene, they suddenly decreased in diversity in Asia while becoming common fishes in the North American fauna. Knowledge of the taxonomy, diversity, and distribution of Eocene catostomids is critical to understanding the evolution of this fish group. We herein describe a new catostomid species of the genus †AmyzonCope, 1872 from the Eocene Kishenehn Formation in Montana, USA. The new species, †Amyzon kishenehnicum, differs from known species of †Amyzon in having hypurals 2 and 3 consistently fused to the compound centrum proximally, and differs from other Eocene catostomids in that the pelvic bone is intermediately forked. All our phylogenetic analyses suggest that the new species is the sister group of †A. aggregatumWilson, 1977 and that †Amyzon is the most basal clade of the Catostomidae. We reassessed the osteological characters of the North American species of †Amyzon from a large number of well-preserved specimens of the new species, as well as †A. gosiutenseGrande et al., 1982 and †A. aggregatum. Osteological characters newly discovered indicate that †A. gosiutense is not a junior synonym of †A. aggregatum, but should be retained as a distinct species.
New cranial and postcranial material of the baenid turtle Neurankylus from the Paleocene Nacimiento Formation (Torrejonian NALMA) of northwestern New Mexico represents a new species, Neurankylus torrejonensis. The material consists of a fragmented but mostly complete skull, a partial carapace and plastron, portions of both humeri, a partial pelvis, a complete right femur, and a distal phalanx. The small, undivided cervical scale, wide vertebrals, complete ring of marginals, and large size (carapace length 520 mm) diagnose the new taxon as belonging to Neurankylus. The narrow fifth vertebral scale and scalloped posterior shell margin reveal affinities with Neurankylus baueriGilmore, 1916, which is known from Campanian sediments in New Mexico and Utah. The holotype of Neurankylus torrejonensis is the youngest known specimen of the Neurankylus lineage, which is known to reach at least back to the Late Cretaceous (Santonian). A nearly complete species-level analysis of baenids confirms the basal placement of Neurankylus outside of Baenodda and the split of Baenodda into two primary subclades, herein named Palatobaeninae and Eubaeninae.
Alligators and caimans share a close relationship, supported by both molecular and morphological characters. The divergence between alligators and caimans has been difficult to discern in the fossil record. Two basal taxa have recently been described from the Miocene of Panama and Venezuela but have not yet been presented in a joint phylogeny. Continued preparation of the type material of the Venezuelan Globidentosuchus brachyrostrisScheyer et al., 2013 has revealed new characters for scoring in a cladistic framework. In addition, the first lower jaw of the Panamanian Centenariosuchus gilmoreiHastings et al., 2013 is described herein, and additional characters were scored. In total, we conducted five cladistic analyses to better understand the character evolution involved in the establishment of Caimaninae. In each case, Globidentosuchus appears as the basal-most of the caimanine lineage, followed by Culebrasuchus mesoamericanusHastings et al., 2013 from Panama. Stepwise character additions of synapomorphies define progressively more derived caimanines, but stratigraphic context creates ghost lineages extending from the Miocene to Paleocene. The persistence of two basal taxa into the Miocene of northern South America and Central America supports the concept of a relict basal population in this region. This further supports biogeographic hypotheses of dispersals in both directions between North and South America prior to full land connection.
Rare remains of hadrosaurian dinosaurs previously reported from the Maastrichtian Javelina Formation of West Texas had been attributed tentatively to either Edmontosaurus or Kritosaurus. Three recently recovered specimens include substantial skull parts and postcranial skeletal elements sufficient to recognize three distinct hadrosaurs. Two species are found in the lower part of the Javelina Formation; one of these is identified as Kritosaurus sp., confirming the earlier referral of specimens to this taxon. The most complete of these specimens combines features thought to be diagnostic of both K. navajoviusBrown, 1910 and ‘Naashoibitosaurus’ ostromiHunt and Lucas, 1993 and exhibits some unique attributes such that its specific identity remains uncertain. A second species, documented by a single specimen found near the base of the Javelina Formation, is inadequate to confidently identify but appears to represent a ‘solid-crested’ saurolophine with frontals having upturned processes along the midline, similar to those that brace the posterior side of the narial crest in Saurolophus. A third hadrosaur is represented at a bonebed in the uppermost part of the Javelina Formation. Its remains are sufficient to justify designation as a new species ?Gryposaurus alsatei. The skull roof elements are similar to those in species of Gryposaurus, and although no parts of the narial crest are preserved, the bordering elements indicate that ?G. alsatei was a ‘flat-headed’ saurolophine. Referral of ?G. alsatei to Gryposaurus would constitute a significant temporal range extension for the genus into late Maastrichtian time, and if correct, this long-lived lineage of hadrosaurs persisted nearly to the end of Cretaceous time in West Texas. ?G. alsatei was a contemporary of Edmontosaurus, the sole terminal Cretaceous hadrosaur in the northern Great Plains region, and neither possessed the ornate narial crest that characterized many earlier hadrosaurs.
Bathornis (“Neocathartes”) grallator (Wetmore, 1944) from the middle Eocene of Wyoming is based on a partial skeleton, which is the most substantial record of the North American Bathornithidae and one of the most complete fossils of a Paleogene stem group representative of the Cariamiformes. So far, however, an assessment of the evolutionary significance of this important fossil has been hampered by the limited published osteological data. Moreover, cariamiform affinities of B. grallator and its true “genus”-level identity were recognized after the last comprehensive revision of the Bathornithidae, and some of its features were incorrectly portrayed in the original description. Here, the B. grallator holotype is restudied and the taxonomic composition and phylogenetic affinities of bathornithids are revised. It is suggested to restrict Bathornithidae to the taxon Bathornis, from which the putative bathornithid Paracrax differs in numerous features, with even cariamiform affinities of this latter taxon not having been established beyond doubt. B. grallator was a flightless bird and has recently been hypothesized to be the sister taxon of the likewise flightless South American Phorusrhacidae. The present analysis, however, supports a position outside a clade including Phorusrhacidae and Cariamidae (the cariamiform crown clade). Owing to their terrestrial way of living, Cariamiformes appear to have been prone to a loss of flight capabilities. B. grallator shows close similarities to a flightless cariamiform bird from the Paleogene of Europe, but the phylogenetic significance of this resemblance is difficult to assess owing to the limited material known of the latter species.
The Otariidae (fur seals and sea lions) are an important and highly visible component of Southern Hemisphere marine mammal faunas. However, fossil material of Southern Hemisphere otariids is comparatively rare and often fragmentary. One exception is the Pleistocene sea lion Neophoca palatinaKing, 1983a, which is known from a nearly complete skull from the North Island of New Zealand. However, the phylogenetic affinities of this taxon are poorly known, and comparisons with other taxa have been limited. We provide an extensive redescription of Neophoca palatina and diagnose this taxon using a morphometric approach. Twenty measurements of the skull were collected for N. palatina, as well as for all extant Australasian otariids and several fossil Neophoca cinereaPerón, 1816. Using principal component analysis, we were able to segregate taxa by genus, and N. palatina was found to cluster with Neophoca according to overall size of the skull as well as increased width of the intertemporal constriction and interorbital region. N. palatina can be distinguished from all other Australasian otariids by its unusually broad basisphenoid. Discriminant function analysis supported referral of Neophoca palatina to Neophoca with very high posterior probability. These results confirm the treatment of Neophoca palatina as a distinct species of Neophoca and highlight the former broad distribution and greater tolerance for colder temperatures of this genus. These results also suggest that New Zealand may have played a pivotal role in the diversification of Southern Hemisphere otariid seals.