Jurassic rhynchonellide brachiopods from the Jordan Valley are herein revised and new taxa are added to the faunal list. In this study of Jurassic rhynchonellides from Wadi Zarqa, northwestern Jordan, we recognize the following taxa: Eurysites rotundus, Cymatorhynchia quadriplicata, Daghanirhynchia triangulata, D. angulocostata, Pycnoria magna, Schizoria elongata, and Schizoria cf. intermedia. The following new taxa are described: Daghanirhynchia susanae sp. nov. and Amydroptychus markowitzi sp. nov. The Middle Jurassic Mughanniyya Formation of northwest Jordan is dominated by limestone beds. The sedimentary environment is interpreted as neritic, light, and nutrient-rich resulting in high faunal diversity. The high rhynchonellide endemism of this fauna is yet another confirmation of pronounced Middle Jurassic endemism along the southern Tethyan margin of the Ethiopian Province. Brachiopods of the Jordanian Mughanniyya Formation can be correlated with the fauna of the Aroussiah Formation in Sinai and the Zohar and Matmor formations in Southern Israel.
Introduction
During the Jurassic Period the Levant was a part of the Gondwanian Tethys platform shelf that extended from Morocco in the west to the Arabian Peninsula, in the east and southward to the Horn of Africa. The collecting area for this study (Fig. 1) is a part of the elevated platform terrain of the Arabian Nubian Shield, which is covered by intermittent Palaeozoic to Cenozoic sedimentary successions consisting mainly of clastic units with marine carbonates increasing upward (Rybakov and Segev 2005). The Late Triassic in the Levant consisted of an area that was covered by broad seamarginal flats, analogous to modern sabkhas, in which evaporites and dolomite rocks were deposited, whereas at the beginning of the Jurassic, emergence led to subaerial exposure that was accompanied by extensive freshwater runoff and subaerial weathering (Goldberg and Friedman 1974). Subsequent subsidence allowed the formation of shallow and marginal shelf environments interrupted by lagoons resulting in the deposition of thick, partly calcareous sandstone beds that were overlain by thick, partly gypsiferous carbonate, marl, and sandy marl rocks (Basha 1980).
Cox (1925) and Muir-Wood's (1925) descriptions of brachiopods and molluscs provided the first reliable data on the age of the Jurassic formations of Jordan. Their faunas were collected in Wadi Zarqa by Bryce Kerr Nairn Wyllie, Keir Arthur Campbell, and George Martin Lees on behalf of the Turkish Petroleum Company, later known as the Anglo-Persian Oil Company (Picard and Hirsch 1987).
This paper is one of a series that was begun with an analysis of the megafossils of northern Sinai (Feldman et al. 1982, 1991; Feldman 1986, 1987; Feldman and Owen 1988, 1993) and Israel (Feldman et al. 2001) in order to systematically study the brachiopod faunas. These data will help establish the history of brachiopod species and their evolution within the Jurassic Ethiopian Province, that is the part of the Tethyan Realm that laid along the southern Tethyan margin. The taxonomic information recorded as a result of these studies will elucidate the biogeographic history of the Ethiopian Province and help to interpret the structure and palaeoecology of its marine communities. For example, in the Jurassic sequence exposed at Hamakhtesh Hagadol, southern Israel, Feldman and Brett (1998) recognised sclerobionts (epi- and endobiontic) organisms on crinoids. Wilson et al. (2008, 2010) further developed the invertebrate community palaeoecological framework.
Fig. 1.
Geographical map of the study area in northwestern Jordan. The collecting localities are indicated by circles: Locality 1, Tel el Dhahab section; Locality 2, Arda section. Modified from Muneizel and Khalil (1993) and Swarieh and Barjous (1993).
Previous studies of Ethiopian Province brachiopods from northern Sinai (Feldman et al. 1982, 1991a; Feldman 1987; Feldman and Owen 1988; Hegab 1988, 1989, 1991, 1992, 1993), along with Cooper's (1989) monograph and Aiméras' (1987) work, complement the present paper on the brachiopods of the Jordan Valley. The Ethiopian Province has been recognised from the Early Jurassic until the mid and possibly end of the Cretaceous by the presence of endemic taxa at the species, genus, and family level. These endemics (e.g., Somalirhynchia africana, Daghanirhynchia daghaniensis, Somalithyris bihendulensis, Striithyris somaliensis, Bihenithyris barringtoni, B. weiri) have been noted, especially in the brachiopods, by Weir (1925) and Muir-Wood (1935). Arkell (1952, 1956) recognised endemic faunas in the ammonoids and Kitchin (1912) in the trigoniacean and crassatellacean bivalves.
The Jurassic brachiopods of Saudi Arabia studied by Cooper (1989) were collected during the years 1933–1953 by field geologists of the Arabian-American Oil Company (Aramco). Cooper (1989) also used the Porter M. Kier-Earl G. Kauffman collections (1962) in his analyses (Gus Arthur Cooper, personal communication 1977). He noted that, whereas several rock types are recorded, some of the specimens cannot be assigned to specific parts of the column, but most have been referred to various ammonite zones. Consequently, it is not possible to determine the palaeoecological conditions under which they existed during the Jurassic. In Jordan, however, collecting was accomplished under strict stratigraphical control and an eventual palaeoecological study of the brachiopods and their communities and a comparison between the Negev communities can be accomplished.
Geographical and geological setting
In northwestern Jordan Jurassic outcrops can be found (Fig. 1) along the western part of Wadi Zarqa beginning near the old Jerash Bridge and extending westward to Deir-Alla, a distance of about 20 km; toward the south the outcrop belt passes through Ain-Khuneizir, Subeihi, and Arda Road (Ahmad 2002). Two outcrops of dolomite and limestone can be found in the Baqa depression near the intersection of Wadi Mahis and Wadi Shueib. The Jurassic succession decreases in thickness from the Zarqa River and Wadi Huni eastward toward the Zarqa Bridge and from there southeast toward Suweileh-1 and Safra-1.
Fig. 2.
Stratigraphical columns of the sections sampled showing lithology and brachiopod yielding beds. A. Arda section. B. Tel el Dhahab section. Abbreviation: L. Cret., Lower Cretaceous.
The Jurassic rocks of Jordan have been subdivided into seven formations: Hihi, Nimr, Silal, Dhahab, Ramla, Hamam, and Mughanniyya (Khalil and Muneizel 1992). The Mughanniyya Formation belongs to the Callovian, the Hamam and Ramla formations belong to the Bathonian and the Dhahab and Silal formations belong to the Bajocian Stage. Blake (1935, 1940) was the first to construct a geological cross section midway between the “Zerqa mouth” and the Jerash Crossing; however, detailed stratigraphic sections were only provided in 1959 by Wetzel and Morton (Picard and Hirsch 1987).
The Mughanniyya Formation (Fig. 2) represents the upper part of the Jurassic sequence in Jordan and outcrops consistently below the Kurnub Sandstone Group. The formation is composed of alternating claystone, siltstone, and marly limestone beds with minor dolomite, dolomitic limestone, and coquinas.
Ammonite zonation
The paucity of ammonites in the Jurassic sediments of Jordan makes the formations difficult to date. Three species of ammonites have been described from northwestern Jordan: Ermoceras cf. coronatoides Douvillé, 1916, Teloceras labrum Buckman, 1922, and Normannites gr. braikenridgii (Buckman, 1927). These taxa, collected from the Dhahab Formation of early middle to late Bajocian age, were described by Basha and Aqrabawi (1994). The closest Jurassic rocks to those in Jordan occur in southern Israel.
The Callovian ammonite biozonation of the sequence at Hamakhtesh Hagadol, southern Israel, was refined by Gill and Tintant (1975), Lewy (1983), Gill et al. (1985), and more recently by Cariou et al. (1997). The same authors and Hirsch et al. (1998) considered the section at Hamakhtesh Hagadol to be a nearly continuous middle to upper Callovian sequence, unique in the Levant, comprising the Erymnoceras coronatum Zone (middle Callovian), Peltoceras athleta Zone (upper Callovian), and Orionoides (Poculisphinctes) poculum Subzone (= lower part of the Quenstedtoceras lamberti Zone). The Callovian ammonite succession in Hamakhtesh Hagadol (Arabic Province) facilitates correlation with the standard scale stages of Submediterranean Europe. Elsewhere in the Middle East, coeval exposures of the Zohar Formation are found at Abu El Darag (Suez Gulf, Egypt), Gebel El-Maghara, and Gebel El-Minshera (northern Sinai, Egypt), in the Hermon Limestone Formation (Antilebanon), and in the Tuwaiq Mountain Limestone Formation (Saudi Arabia). Coeval sequences of the upper Callovian Matmor Formation (nearly 100 m thick) are only found in the Negev boreholes at Qeren, Sherif, Rehkme, Boqer, and the Hallal borehole in Sinai, Egypt, all of which are part of the platform of the Higher Negev (Picard and Hirsch 1987). In the Gebel El-Maghara section (Sinai Deep) and in the Hermon exposures of the Judean Embayment (Hirsch et al. 1998), the later Callovian is reduced to a few dm of section covered by Oxfordian shales (Cariou et al. 1997).
Goldberg (1963) subdivided the 206-m-thick section at Hamakhtesh Hagadol into 69 subunits (numbered 5–74). The sequence consists of the Ziyya and Madsus members of the Zohar Formation (Coates et al. 1963) and of the Matmor Formation (Goldberg 1963, emended Hirsch and Roded 1997).
Material and methods
All specimens are preserved as articulated shell material. The specimens are from the Hamam and Mughanniyya formations (Bathonian—Callovian) in northwest Jordan. Serial sections were prepared with a WOKO 50P grinding machine with slice-spacing of 100 to 200 µm. Drawings were made with the help of a camera lucida. Measurements were taken with digital caliper and rounded to 0.1 mm. Specimens were coated with ammonium chloride prior to photographing. All measurements are in millimetres (mm); the width of the dorsal fold is measured at the anterior commissure. Est. indicates the specimen was incomplete and the measurement was estimated. The systematics follows the revised Treatise on Invertebrate Palaeontology (Manceñido et al. 2002).
Institutional abbreviations.—AMNH, Division of Palaeontology, American Museum of Natural History, New York, NY, USA; GSI, Geological Survey of Israel, Jerusalem, Israel; USNM, United States National Museum, Smithsonian Institution, Washington, D.C., USA.
Other abbreviations.—L, length; T, thickness; W, width.
Systematic palaeontology
Phylum Brachiopoda Duméril, 1806
Subphylum Rhynchonelliformea Williams, Carlson, Brunton, Holmer, and Popov, 1996
Class Rhynchonellata Williams, Carlson, Brunton, Holmer, and Popov, 1996
Order Rhynchonellida Kuhn, 1949
Superfamily Hemithiridoidea Rzhonsnitskaya, 1956
Family Cyclothyrididae Makridin, 1955
Subfamily Cardinirhynchiinae Makridin, 1964
Genus Eurysites Cooper, 1989
Type species: Eurysites transversus Cooper, 1989; Bajocian/Callovian, Saudi Arabia.
Eurysites rotundus Cooper, 1989
Fig. 3A.
1989 Eurysites rotundus sp. nov.; Cooper 1989: 32–33, pl. 8: 27–49, pl. 17: 1–11, fig. 17.
Material.—Three articulated specimens: AMNH FI-72366, AMNH FI-72367, AMNH FI-72368, bed S-7, Mughanniyya Formation, Tel el Dhahab section, Jordan.
Description.—Shell medium size (Table 1), somewhat worn, outline roundly triangular and almost pyriform but slightly rounded at margins, length almost equal to width; strongly dorsibiconvex; anterior commissure uniplicate, lateral commissure straight but rises slightly posteriorly. Ventral beak straight, long, and pointed; costae high, subangular, numbering about 14.
Ventral valve broadly convex in anterior view, less convex in lateral view. Ventral interarea appears high but partially obscured as is the pedicle foramen. Umbo convex, swollen, becoming flatter anteriorly; sulcus low bearing 4 costae, flanks slightly curved with 10 costae.
Dorsal valve with weakly defined fold rising slightly above flanks begins just past midlength becoming more distinct near anterior commissure. The fold bears 5 costae, with 8 costae on each dorsal flank; flanks rounded when viewed anteriorly. In lateral view convexity of dorsal valve is at maximum at midvalve; sides steep.
Due to a paucity of material we did not section any specimens. However, Cooper (1989) illustrates transverse serial sections which show relatively thick dental plates that disappear before midvalve. His dorsal valves have a very short median septum or ridge with thick outer hinge plates; the crura are raduliform with well developed bases.
Discussion.—Eurysites rotundus differs from E. transversus (see Cooper 1989: fig. 18; pl. 8: 50–59; pl. 9: 1–16; pl. 17: 12) in its triangular shape and more swollen dorsal valves that are distinctly more convex in lateral view and less elliptical outline. On our specimen of E. rotundus there are no fila visible possibly due to the somewhat weathered shell surface. Cooper (1989) noted that on his specimens of E. rotundus from Saudi Arabia (housed in the USNM) there were fine concentric fila in the interspaces between the costae. E. rotundus is similar to Flabellirhynchia Buckman, 1918 from the Bajocian of Great Britain in its elongated beak and outline. It resembles Flabellirhynchia delicata (Buckman 1918: pl. 19: a–c) in general outline but differs in its lower fold, thicker and stubbier anterior commissure and longer beak.
Remarks.—The genera Cymatorhynchia and Flabellirhynchia were introduced by Buckman (1918) in a paper that has been dated originally as 1917, however, the footnote to Corrigenda sheet from the Geological Survey of India states: “Print off orders regarding this memoir were given to the press in September, 1917, but owing to shortage of paper, copies were not actually issued till July, 1918”; Shi and Grant (1993: 144). As not all following authors noticed the actual publication date Cymatorhynchia and Flabellirhynchia are cited in some papers as 1918 and elsewhere as 1917.
Stratigraphic and geographic range.—Bajocian to Callovian; Saudi Arabia, Jordan.
Table 1.
Measurements (in mm) of Eurysites rotundus Cooper, 1989.
Fig. 3.
Jurassic rhynchonellide brachiopods from Jordan. A. Eurysites rotundus Cooper, 1989. Articulated specimen (AMNH FI-72366), bed S-7, Mughanniyya Formation, Tel el Dhahab, Jordan, in ventral (A1), dorsal (A2), posterior (A3), anterior (A4), and lateral (A5) views. B. Cymatorhynchia quadriplicata (Zieten, 1830). Articulated specimen (GSI M 2975), bed 21a, Hamam Formation, Arda, Jordan, in ventral (B1), dorsal (B2), posterior (B3), anterior (B4), and lateral (B5) views. C. Daghanirhynchia susanae sp. nov. Articulated specimen, holotype (AMNH FI-72380), bed S-7, Mughanniyya Formation, Arda section, Jordan, in ventral (C1), dorsal (C2), posterior (C3), anterior (C4), and lateral (C5) views. D. Daghanirhynchia angulocostata Cooper, 1989. Articulated specimen (AMNH FI-72395), bed S-7, Mughanniyya Formation, Tel el Dhahab, Jordan, in ventral (D1), dorsal (D2), posterior (D3), anterior (D4), and lateral (D5) views. E. Daghanirhynchia triangulata Cooper, 1989. Articulated specimen (AMNH FI-72398), bed 21a, Hamam Formation, Arda, Jordan, in ventral (E1), dorsal (E2), posterior (E3), anterior (E4), and lateral (E5) views. F. Pycnoria magna Cooper, 1989. Articulated specimen (AMNH FI-72399), bed 21a, Hamam Formation, Arda, Jordan, in ventral (F1), dorsal (F2), posterior (F3), anterior (F4), and lateral (F5) views. G. Amydroptychus markowitzi sp. nov. AMNH FI-72405, holotype, bed S-7, Mugannhiyya Formation, Arda section, Jordan, in ventral (G1), dorsal (G2), posterior (G3), anterior (G4), and lateral (G5) views. H. Schizoria elongata Cooper, 1989. Articulated specimen (AMNH FI-72408), bed S-7, Mughanniyya Formation, Tel el Dhahab section, Jordan, in ventral (H1), dorsal (H2), posterior (H3), anterior (H4), and lateral (H5) views. I. Schizoria cf. intermedia Cooper, 1989. Articulated specimen (AMNH FI-72409), bed 21b, Hamam Formation, Arda section, Jordan, in ventral (I1), dorsal (I2), posterior (I3), anterior (I4), and lateral (I5) views.
Family Tetrarhynchiidae Ager, 1965
Subfamily Tetrarhynchiinae Ager, 1965
Genus Cymatorhynchia Buckman, 1918
Type species: Rhynchonella cymatophorina Buckman, 1910; Aalenian to upper Bajocian of Europe, Africa, Saudi Arabia, India, Burma, China, and Tibet.
Cymatorhynchia quadriplicata (Zieten, 1830) Figs. 3B, 4.
1830 Terebratula quadriplicata; Zieten 1830: 55, pl. 41: 3.
1851 Terebratula quadriplicata; Quenstedt 1851: 453, pl. 36: 16; 1858: 423, pl. 58: 5–8; 1868–1871, pl. 38: 42.
1851–1852 Rhynchonella quadriplicata (Zieten); Davidson 1851–1852: appendix: 23, pl. A: 22; 201, pl. 29: 1–3.
1918 Cymatorhynchia quadriplicata (Zieten); Buckman 1918: 53–54.
1918 Rhynchonella quadriplicata (Zieten); Rollier 1918: 148.
1936 Rhynchonella quadriplicata (Zieten); Arcelin and Roche 1936: 59, pl. 2: 1–6, pl. 11: 1,4, 5, pl. 12: 5, pl. 13: 3, 4.
1939 Rhynchonella quadriplicata (Zieten); Roche 1939: 268, pl. 4: 11.
1965 Cymatorhynchia quadriplicata (Zieten in Davidson); Rousselle 1965: 52, pl. 2: 11, 12.
1966 Cymatorhynchia quadriplicata (Zieten); Aiméras 1966: 70–97, 73, pl. F–G, pl. 2: 5–8.
1966 Cymatorhynchia quadriplicata var. vergissonensis; Aiméras 1966: 79, pl. D–E, pl. 2: 1–4.
1966 Cymatorhynchia quadriplicata var. lata; Aiméras 1966: 88, pl. I, pl. 4: 6–8.
1966 Cymatorhynchia quadriplicata var. depressa; Aiméras 1966: 95.
1966 Cymatorhynchia quadriplicata var. trilobata; Aiméras 1966: 96.
1969 Cymatorhynchia quadriplicata (Zieten); Pevny 1969: 143, pl. 28: 1a–c.
1980 Cymatorhynchia quadriplicata (Zieten); Fischer 1980: 140, pl. 58: 1, 2.
1981 Cymatorhynchia quadriplicata (Zieten); Parnes 1981: 21, pl. 2: 5–13.
1987 Cymatorhynchia quadriplicata (Zieten); Shi 1987: 55, pl. 3: 12.
1993 Cymatorhynchia quadriplicata (Zieten, 1830); Shi and Grant 1993: 72–73, pl. 7: 17–19, pl. 8: 8–13, pl. 9: 1–7, 11–17, pl. 12: 1, 2, 6, 7.
1996 Cymatorhynchia quadriplicata (Zieten, 1830); Aiméras and Elmi 1996: pl. 1: 21.
Material.—42 articulated specimens: AMNH FI-72369 (sectioned), AMNH FI-72370, bed S-7, AMNH FI-72371, AMNH FI-72372, AMNH FI-72373, AMNH FI-72374, AMNH FI-72375, bed S-10, Mughanniyya Formation, Tel el Dhahab section; AMNH FI-72376, bed 21a, AMNH FI-72377, bed 21b, AMNH FI-72378-79, bed 25, Hamam Formation, Arda section GSIM 2975, GSIM 742, GSIM 4510, GSIM 4522, GSI M 4539, GSI M 4553, GSI M 4556, GSI M 4565 (collected from the Tel el Dhahab section but beds not identified), Jordan.
Description.—Shells medium to large (Table 2), subpentagonal to subquadrate in outline, moderately dorsibiconvex, maximum width near midlength. Anterior commissure widely uniplicate. Ventral beak short, suberect to erect, deltidial plates disjunct to conjunct; costae subangular to sharp numbering about 16–17; growth lines barely visible near anterior commissure.
Ventral valve moderately to strongly convex posteriorly but less convex anteriorly; a broad, shallow sulcus originates just past one-third of valve length bearing 3–4 strong subangular costae, 5–6 costae on ventral flank; foramen round, small to medium sized, ventral interarea low.
Dorsal valve more globose posteriorly, flattened toward anterior commissure; moderately convex in lateral view; a broad, low fold originates just posterior to midlength bearing 4 costae with 6 costae on dorsal flank.
Interior. Very short, low dorsal median septum, strong dental plates parallel to subparallel anteriorly in one sectioned specimen, teeth short, somewhat bulbous; septalium not preserved, outer hinge plates subhorizontal arched slightly ventrally, sockets deep, asymmetrical, crura raduliform.
Discussion.—The shells differ from Cymatorhynchia? singularis (USNM 303631) of Cooper (1989) in possessing less costae, a more inflated dorsal valve and less tumid ventral posterior. Buckman's (1918: pl. 17: 15a, c) C. cymatophorina is wider and has finer and more numerous costae (about 26 on the dorsal valve). Cymatorhynchia quadriplicata var. inflata Alméras (USNM 319165) has a more subcircular outline, more inflated dorsal valve, finer and denser ribs as well as a less developed fold and sulcus as noted by Shi and Grant (1993). They also noted that the Tethyan form varies considerably in morphology and was split into seven variants by Alméras (1966). Five of the variants (except for C. quadriplicata var. densecosta and C. quadriplicata var. inflata) have the same basic characteristics namely, less tumid dorsal than ventral valve, slightly depressed shell, subpentagonal outline, and few but strong ribs. Shi and Grant therefore regard them as a single variable species: C. quadriplicata (Zieten, 1830). They suggest combining the varieties C. quadriplicata denecosta and C. quadriplicata var. inflata into a single species: Cymatorhynchia denecosta Aiméras, 1966. Alméras and Elmi (1996) describe a specimen of C. quadriplicata var. inflata from Toulon, France, that is larger (USNM 541691: L, 30.3; W, 29.4 [est.]; T, 24.8), much more gibbous and has finer and more numerous costae (about 26). C. quadriplicata var. inflata from Württemberg, Germany, has similar dimensions (USNM 541692: L, 30.1; W, 33.0; T, 24.4) but the costae are less numerous (20) and sturdier.
Stratigraphic and geographic range.—Bathonain to Callovian; England, France, Jordan, Ethiopia.
Table 2.
Measurements (in mm) of Cymatorhynchia quadriplicata (Zieten, 1830).
Fig. 4.
Serial sections of the rhynchonellide brachiopod Cymatorhynchia quadriplicata (Zieten, 1830). AMNH FI-72369. Bed 21a, Hamam Formation, Arda, Jordan. Numbers describe sectional distance from apex. Abbreviations: c, crus; cb, crural base; dms, dorsal median septum; dp, dental plate; isr, inner socket ridge; osr, outer socket ridge; s, socket; sp, septalial plate; ssm, secondary shell material; t, tooth.
Genus Daghanirhynchia Muir-Wood, 1935
Type species: Daghanirhynchia daghaniensis Muir-Wood, 1935; Callovian, Somalia.
Daghanirhynchia susanae sp. nov.
Figs. 3C, 5.
Etymology: Latinization of Susan after Susan Feldman.
Holotype: Articulated specimen AMNH FI-72380.
Type locality: Wadi Zarqa, Arda Section, Jordan.
Type horizon: Bed S-7, Mughanniyya Formation, Callovian (upper Middle Jurassic).
Material.—45 articulated shells: AMNH FI-72380, AMNH FI-72381, AMNH FI-72386, AMNH FI-72388, AMNH FI-72393, AMNH FI-723410 (sectioned) bed S-7, AMNH FI-72394, bed S-10, AMNH FI-72383, AMNH FI-72387, AMNH FI-72391, AMNH FI-72392, Mughanniyya Formation, Arda section; AMNH FI-72382, AMNH FI-72384, bed 21a, AMNH FI-72389, bed 21b, AMNH FI-72385, Hamam Formation, Arda section; GSI M 731, GSI M 732, GSI M 741, GSI M 743, GSI M 4506, GSI M 4552, GSI M 4558 (collected from the Tel el Dhahab section but beds not identified), Jordan.
Diagnosis.—Coarsely plicated Daghanirhynchia with long, narrow fold bearing 3 costae.
Description.—The shells are medium size (Table 3), subpentagonal in outline, dorsibiconvex, maximum width at about midlength; strongly uniplicate anterior commissure, lateral commissure straight, beak suberect to erect, costae strong and coarse and narrow, numbering 12–16 but commonly 12–13, linguiform extension moderate. Anterior margin ends abruptly, stubby.
Ventral valve gently convex to almost flat in lateral view, concave in anterior profile. Sulcus originates just anterior to umbonal region, occupied by 2–3 costae. Foramen small, deltidial plates disjunct.
Dorsal valve moderately convex in lateral profile, fold originates just anterior to umbonal region, very narrow, highly elevated above flanks, occupied by 3 costae.
Dental plates parallel in posterior region of shell but diverge anteriorly from ventral floor. Teeth short, bulbous without crenulations; dorsal median septum short, reduced to low ridge, and finally disappearing at about one-third valve length. Hinge plates horizontal, very broad, and separated; septalium not preserved; crura raduliform. Secondary thickening in umbonal chambers.
Discussion.—Daghanirhynchia susanae sp. nov. differs from the type species D. daghaniensis Muir-Wood, 1935 in having coarser costae and a longer narrower fold. D. macfadyeni Muir-Wood, 1935 differs in that its fold is never raised above the level of the lateral slopes and bears a low, median fold. D. elongata Muir-Wood, 1935 is generally longer with finer costae and a shorter sulcus. The umbo in D. elongata extends further posteriorly than in D. susanae. Daghanirhynchia macfadyeni Muir-Wood, 1935 is characterised by a more convex ventral valve, a shallower shorter sulcus, and 4 costae on the fold. The costae of D. macfadyeni are finer than in D. susanae but may reach the same thickness in a few specimens. D. platiloba Muir-Wood, 1935 differs from the new species in having a less convex dorsal valve, a longer ventral umbo, and a shallower, shorter sulcus. D. kabeitensis Muir-Wood, 1935 is wider than D. susanae and has a longer ventral umbo. The size of costae and sulcus is the same as in D. susanae, D. farquharsoni Muir-Wood, 1935 is equibiconvex, whereas the specimens of D. susanae are clearly dorsibiconvex. The sulcus in D. farquharsoni is shallower than in D. susanae and sulcus and fold are rectangular in cross section, whereas in D. susanae the fold and sulcus are broadly rounded in cross section.
Stratigraphie and geographic range.—Bathonian to Callovian; Jordan.
Fig. 5.
Serial sections of rhynchonellide brachiopod Daghanirhynchia susanae sp. nov. AMNH FI-72410. Bed 21b, Hamam Formation, Arda, Jordan. Numbers describe sectional distance from apex. Abbreviations: c, crus; cb, crural base; dms, dorsal median septum; dp, dental plate; isr, inner socket ridge; osr, outer socket ridge; s, socket; sp, septalial plate; ssm, secondary shell material; t, tooth; vms, ventral median septum.
Table 3.
Measurements (in mm) of Daghanirhynchia susanae sp. nov.
Daghanirhynchia angulocostata Cooper, 1989
Fig. 3D.
1989 Daghanirhynchia angulocostata sp. nov.; Cooper 1989: 26–28, pl. 6: 1–19, pl. 7: 44–53, pl. 11: 16–21, figs. 13, 14.
Material.—Two articulated specimens: AMNH FI-72395, AMNH FI-72396, bed S-7, Mughanniyya Formation (Callovian, upper Middle Jurassic), Tel el Dhahab section, Jordan.
Description.—Shells large (Table 4), outline widely triangular with maximum width anterior to midlength. Anterior commissure strongly uniplicate; costae coarse and subangular in cross section, 14–15 in number; ventral beak narrow, suberect; ventral interarea low. Foramen medium to large, longitudinally oval to suboval. Deltidial plates disjunct.
Ventral valve almost flat in lateral view, umbonal region moderately swollen. Sulcus originates just posterior to midlength and deepens anteriorly with 3–4 costae. Linguiform extension moderate with narrow, slightly convex flanks adjacent to sulcus with 6–7 costae.
Dorsal valve moderately convex in lateral profile, moderately to gently domed in anterior view; fold originates just posterior to midvalve but in some shells at midvalve, elevating slightly with 4 costae, 6 costae on dorsal flank.
The internal structures of the shells are unknown due to a lack of sufficient material for serial sectioning.
Discussion.—The Jordanian specimens compare favourably with Cooper's (1989) shells in that they are large and widely triangular with maximum width anterior to midlength. Muir-Wood's (1935) description of the genus includes the presence of fine radial striae as a feature of the genus. Cooper (1989) did not observe these features on his shells from Saudi Arabia and found none on the specimens in the USNM collections from the type locality of D. daghaniensis MuirWood, 1935 (USNM 75665, 75666). The Jordanian shells are also lacking this feature as well as the thickened deltidial plates observed by Cooper (1989) in his Saudi Arabian shells.
Stratigraphic and geographic range.—Bathonian to Callovian, Saudi Arabia, Jordan.
Table 4.
Measurements (in mm) of Daghanirhynchia angulocostata Cooper, 1989.
Daghanirhynchia? triangulata Cooper, 1989
Fig. 3E.
1989 Daghanirhynchia? triangulata sp. nov.; Cooper 1989: 28–29, pl. 7: 6–21, pl. 11: 11–15.
Material.—Two articulated specimens: AMNH FI-72397, bed S-7, Mughanniyya Formation (Callovian, upper Middle Jurassic), Tel el Dhahab section; AMNH 72398, bed 21a, Hamam Formation, Arda section, Jordan.
Description.—There are two shells in the collection (Table 5) tentatively assigned to Daghanirhynchia? triangulata Cooper, 1989. The specimens are triangular with maximum width considerably past midlength; slightly dorsibiconvex, strongly uniplicate anterior commissure, lateral commissure straight, beak suberect, costae strong, coarse and narrow, numbering 16–17.
Ventral valve barely convex in lateral view, almost flat, concave in anterior profile. Sulcus originates just past umbonal region, occupied by three costae. Linguiform extension long and fairly narrow; ventral interarea low; 6–7 costae on flanks.
Dorsal valve slightly convex in lateral view, strongly domed in anterior view, sides becoming steeper as lateral margins approached. Fold begins at about midlength, occupied by 4 costae, slightly less than half the valve width; 6 costae on flanks.
The internal structures of the shells are unknown due to a lack of sufficient material for serial sectioning.
Discussion.—The shell closely resembles Cooper's (1989) Daghanirhynchia? triangulata in its triangular outline and costation and is tentatively placed in that taxon until additional material can be studied.
Stratigraphic and geographic range.—Callovian, Jordan.
Table 5.
Measurements (in mm) of Daghanirhynchia? triangulata Cooper, 1989.
Genus Pycnoria Cooper, 1989
Type species: Pycnoria magna Cooper, 1989; Callovian, Saudi Arabia.
Pycnoria magna Cooper, 1989
Figs. 3F, 6.
1989 Pycnoria magna sp. nov.; Cooper 1989: 53–54, pl. 12: 11–36, pl. 18: 26–36, figs. 29, 30.
1991 Pycnoria magna Cooper; Feldman et al. 1991: 15, figs. 11A–C.
Material.—Six articulated specimens: AMNH FI-72402, AMNH FI-72404, AMNH FI-72403 (sectioned), bed S-7, AMNH FI-72400, bed S-20, Mughanniyya Formation (Callovian, upper Middle Jurassic), Tel el Dhahab section, AMNH FI-72401, bed 25, Mughanniyya Formation Formation (Callovian, upper Middle Jurassic), Arda section; AMNH FI-7299, bed 21, Hamam Formation (Bathonian, Middle Jurassic), Arda section, Jordan.
Description.—The shells are medium to large (Table 6) with rounded sides and an obtuse apical angle. Maximum width is at or slightly anterior to midvalve; outline subpentagonal, dorsal valve deeper and more convex than ventral valve. Lateral commissure straight, anterior commissure uniplicate. Beak short, erect to incurved; ventral interarea low, foramen hypothyrid, deltidial plates small, conjunct. Costae coarse and angular in cross-section numbering about 13–17. Some shells (AMNH FI-72399, AMNH FI-72400, AMNH FI-72401) have a relatively long linguiform extension.
Ventral valve flat in lateral profile but slightly convex in umbonal region; in anterior profile valve is shallowly concave. Low sulcus originates about one-third of distance from beak, deepening anteriorly; sulcus generally bears 3 costae and widens narrowly in some specimens but widely in others. Flanks narrow, steep bearing 4 costae.
Dorsal valve evenly convex in lateral profile, strongly to moderately domed in anterior view, with a well-defined arcuate median fold somewhat to strongly elevated above steep flanks. Fold narrow, originating at about midlength bearing 3–4 costae, usually 4. Flanks bear 5 costae.
Dental plates thick, long, and slightly divergent (less than 5°) from valve floor, shell relatively thin, median septum low, very weak. Strong, swollen slightly subquadrate hinge teeth fit into large sockets, crura raduliform, septalium appears to be narrow and short; crural bases weak. One tooth is somewhat corrugated. The general transverse outlines of Cooper's (1989) shells are similar to the Jordanian shells, the height of which is similar as is the presence of the median septum.
Discussion.—These specimens of Pycnoria magna compare favourably with the specimens described by Feldman et al. (1991) in that they also have 13 strong, angular, deeply incised costae with a well-defined arcuate median dorsal fold and a comparatively narrow sulcus. The Jordanian shells display more variability in that some have a more highly developed median dorsal fold and a slightly wider and more broadly arcuate anterior commissure, similar to that of Strongyloria circularis Cooper, 1989. Cooper's (1989) species of Pycnoria magna (USNM 303631; 243375) differs in that they have very fine concentric lines crossing the costae, a feature that may well have been removed here by exfoliation. Pycnoria differs from common rhynchonellides such as Somalirhynchia and Daghanirhynchia in its more solid and compact form as noted by Cooper (1989). We are in agreement with him that it differs from Globirhynchia triangulata in its stronger costation, narrower fold and deeper sulcus. Burmirhynchia is generally smaller with fewer costae (see Buckman 1918).
Stratigraphic and geographic range.—Bathonian to Callovian; Saudi Arabia, Jordan.
Table 6.
Measurements (in mm) of Pycnoria magna Cooper, 1989. *, sectioned.
Fig. 6.
Serial sections of rhynchonellide brachiopod Pycnoria magna Cooper, 1989. AMNH FI-72403. Bed 25, Hamam Formation, Arda, Jordan. Numbers describe sectional distance from apex. Abbreviations: c, crus; cb, crural base; dms, dorsal median septum; dp, dental plate; isr, inner socket ridge; osr, outer socket ridge; pf, pedicle foramen; s, socket; t, tooth.
Subfamily Gibbirhynchiinae Manceñido, Owen,
Dongli, and Dagys, 2002
Genus Amydroptychus Cooper, 1989
Type species: Amydroptychus formosus Cooper, 1989; Bajocian of Saudi Arabia.
Amydroptychus markowitzi sp. nov. Fig. 3G.
Etymology: Named in memory of Alfred Markowitz (1926–2000), scientist, Renaissance Man, and healer.
Holotype: AMNH FI-72405.
Type locality: Arda section, Wadi Zarqa, Jordan.
Type horizon: Bed 27, Mughanniyya Formation (Callovian, upper Middle Jurassic).
Material.—Two articulated specimens: AMNH FI-72405 (holotype), AMNH FI-72406, bed 27, Mughanniyya Formation (Callovian, upper Middle Jurassic); Arda section, Jordan.
Diagnosis.—Amydroptychus with subcircular outline, equibiconvex, medium to large foramen, and rectimarginate anterior commissure with no indication of fold or sulcus.
Description.—Medium-sized shells (Table 7), outline subcircular and equibiconvex in longitudinal section without any indication of fold or sulcus. Ventral valve covered by 20 simple costae, dorsal valve by 21 costae. Furrows and costae are angular to rounded in cross section. Equibiconvex, apical angle acute, deltidial plates obscured, foramen medium, tubular. Anterior commissure rectimarginate; lateral commissure straight. Ventral beak erect in adults but suberect in juveniles. Twenty-one angular costae on adults and 25 on juveniles. Intercalations and bifurcations observed on juveniles but rare on adult specimens.
The ventral valve is convex in lateral profile with the apex of the convexity occurring at one-third the distance from the beak; in anterior profile the valve is more sharply domed with the flanks sloping somewhat steeply until the commissure is reached.
The dorsal valve is convex in lateral view bulging more posteriorly and sloping gently toward the anterior commissure. In the juvenile specimens the bulge is less developed.
The internal structures of the shells are unknown due to a lack of sufficient material for serial sectioning.
Discussion.—The gentle folding that Cooper (1989) noted as being a conspicuous feature of Amydroptychus formosus is absent here. These specimens resemble Strongyloria circularis Cooper, 1989 but are less globose, lack an arcuately uniplicate anterior commissure, and have a narrower beak. In addition, these shells are more triangular than circular in outline as are Strongyloria circularis and S. subelliptica Cooper, 1989. Hegab (2005) described Amydroptychus galaensis from the Jurassic of the western side of the Gulf of Suez, Egypt, that differs from the Jordanian shells in their slightly sulcate anterior commissure (2005: 740, figs. 3, 6) and smaller number of costae (16).
Stratigraphic and geographic range.—Callovian; Jordan.
Table 7.
Measurements (in mm) of Amydropthychus markowitzi sp. nov. *, rectimarginate anterior commissure.
Genus Schizoria Cooper, 1989
Type species: Schizoria elongata Cooper, 1989; Bajocian of Saudi Arabia.
Schizoria elongata Cooper, 1989
Fig. 3H.
1989 Schizoria elongata sp. nov.; Cooper 1989: 55–56, fig. 31: 14, figs. 17–27.
Material.—Three articulated specimens: AMNH FI-72407, AMNH FI-72408, AMNH FI-72411, bed S-7, Mughanniyya Formation (Callovian, upper Middle Jurassic); Tel el Dhahab section, Jordan.
Description.—Shells small (Table 8), elongate but slightly oval, maximum width just anterior to midvalve. Dorsal valve deeper and asymmetrically more convex than ventral valve with the convexity more pronounced posteriorly; apical angle acute; anterior commissure on larger shell barely uniplicate but on smaller shell not preserved well enough to determine morphology; lateral commissure straight. Beak narrow, long; foramen medium, mesothyrid, tubular; deltidial plates disjunct, ventral interarea low. Costae moderate and angular in cross section but subangular and rounded on smaller shell due to weathering and exfoliation; bifurcated and intercalated mostly on umbos ranging from 24–25 in number.
Ventral valve moderately convex in lateral profile and highly domed in anterior view. Umbonal region swollen, more so in large shell. Fold with 5 costae; 6 to 7 costae on flank of ventral valve.
Dorsal valve swollen posteriorly but less so in smaller specimen; highly domed in anterior view on the larger shell. Sulcus with 4 costae; 5 to 7 costae on flank.
The internal structures of our shells are unknown due to a lack of sufficient material for serial sectioning.
Discussion.—The shells closely resemble Cooper's (1989) Schizoria elongata in many respects but differ in that the pedicle foramen here is mesothyrid and is slightly larger than in his specimens. Schizoria intermedia Cooper, 1989 has more widely spaced costae on the flanks, fold, and sulcus with no bifurcations and rare intercalations; it also has a strongly uniplicate anterior commissure. Sphenorhynchia plicatella differs from Schizoria elongata in its less elongate-oval general outline, more evenly biconvex valves, shorter and more massive umbo, and less numerous costellae.
Stratigraphie and geographic range.—Bajocian to Callovian; Saudi Arabia, Jordan.
Table 8.
Measurements (in mm) of Schizoria elongata Cooper, 1989. *, rectimarginate anterior commissure.
Schizoria cf. intermedia Cooper, 1989
Fig. 3I.
Material.—One articulated specimen, AMNH FI-72409, bed 21b, Hamam Formation (Bathonian, middle Middle Jurassic); Arda section, Jordan.
Description.—Shell small (L = 21.6; W = 20.0; T = 15.4), elongate oval in longitudinal direction, maximum width anterior of midvalve, dorsal valve more globose than ventral valve; sides rounded, anterior commissure strongly uniplicate; ventral beak and foramen damaged; lateral commissure straight; about 17 angular to subangular costae with no bifurcations or intercalations.
Ventral valve slightly convex in lateral view, gently domed and almost flat on top, umbonal region barely swollen; sulcus broad and shallow, originating at midvalve, bearing 4 costae.
Dorsal valve moderately convex in lateral profile, and evenly but narrowly domed in anterior view; fold beginning almost at midvalve, bearing 5 costae.
The internal structures are unknown due to a lack of sufficient material for serial sectioning.
Discussion.—The shell resembles Schizoria intermedia Cooper, 1989 but a definite taxonomic assignment cannot be made at this time due to inadequate material for serial sectioning and a damaged beak on the single specimen in the collection.
Stratigraphic and geographic range.—Bathonian, Jordan.
Paleobiogeography
Limestone beds dominate the Middle Jurassic Mughanniyya Formation of northwest Jordan with minor admixture of marl and claystone. Most of the Jurassic rocks of Jordan were deposited in shallow water, nearshore environments where food supply and light were not likely to have been limiting factors (Wolff 1973) which explains the high and diverse faunal content. The environment of deposition appears to have been neritic. We hope to provide data that will enable a more precise stratigraphic correlation between the strata in northwestern Jordan and southern Israel (e.g., Hamakhtesh Hagadol or Kurnub Anticline). Lewy (1983) noted that the lithostratigraphic correlation of the strata in the Zarqa River area with those in Israel lacks the necessary biostratigraphic data for the recognition of the equivalents to the Upper Callovian Zohar and Kidod formations in Jordan. During the Callovian there was a continuous platform sedimentation regime and a regional sea level high during Middle and Upper Callovian times that inundated most of the Arabian Platform with carbonates. In Sinai (Gebel el-Maghara) these limestone rocks built up the Aroussiah Formation. In the southern Negev the sequence appears to contain more marls (Hamahktesh Hagadol) and is known as the Zohar and Matmor formations (Hirsch et al. 1998; Hirsch 2005). In Jordan, the Mughanniyya Formation represents only the lowermost part of the Zohar Formation, as the youngest portion of the interval was eroded in infra-Cretaceous times (see Goldberg and Friedman 1974). It is of utmost interest as it represents a lower interval that is not exposed in the Jurassic of southern Israel (Hamahktesh Hagadol). These rocks yielded a fauna that is related to Ethiopian-Somali taxa (brachiopods, bivalves [e.g., Eligmus Eudes-Deslongchampes, 1856], gastropods and foraminiferans [e.g., Kurnubia lineage]). The northeastern Ethiopian Province was part of a broad shelf surrounding the Arabo-Nubian craton in the Middle Jurassic (Lewy 1983). Shelf and marginal marine flats with mostly carbonates and evaporites dominated the broad platform of northern Gondwana, whereas southern Tethyan Seaway deep water basinal limestone, radiolarian chert, and ophiolites (Goldberg and Friedman 1974) characterise obstructed terranes to the north along the Cyprus Arc and Assyrian Suture (Krashennikov et al. 2005).
A high degree of endemism characterises the rhynchonellide brachiopod faunas of the Jurassic Ethiopian Province. In the Sinai Peninsula (Gebel el-Maghara), southern Israel (Hamahktesh Hagadol), and in Saudi Arabia (Dhruma, Tuwaiq Mountain, and Hanifa formations) Somalirhynchia is relatively widespread but absent in correlative rocks in Jordan. In Hamahktesh Hagadol Somalirhynchia and Burmirhynchia occur in the Late Callovian Matmor Formation that are missing in Wadi Zarqa, Jordan. However, we have identified Eurysites, Cymatorhynchia, Daghanirhynchia, Pycnoria, Schizoria, and Amydroptyhcus from the early—middle Callovian Mughanniya Formation in Jordan. Cooper (1989) noted the high degree of endemism in a Saudi Arabian brachiopod fauna in which he described 13 new rhynchonellide genera (Dhruma, Tuwaiq Mountain, and Hanifa formations). Kier (1972) noted an extremely high degree of endemism in his study of Jurassic echinoids of Saudi Arabia; 24 out of 27 taxa were new. Muir-Wood's (1925) Jordan Valley fauna and Weir's (1925) Somalia fauna were not included here due to the lack of reliable identification since interior sections of these taxa are not available.
Acknowledgements
We are grateful to Chaim Benjamini (Ben-Gurion University of the Negev, Israel) for helpful suggestions that greatly improved the paper. We thank Jann Thompson and Daniel Levin (National Museum of Natural History/Smithsonian Institution, Washington DC, USA) and Lee Davies (Natural History Museum, London, UK) for providing access to the brachiopod collection. Many thanks are due Juliane Eberhardt and Erika Scheller-Wagner (Forschungsinstitut and Naturmuseum Senckenberg, Frankfurt am Main, Germany) for technical help. We thank Fernando Alvarez (Universidad de Oviedo, Oviedo, Spain) and Attila Vörös (Hungarian Natural History Museum, Budapest, Hungary) for their constructive and helpful reviews of the manuscript. The visit of MS-G to the American Museum of Natural History, New York was supported by a Lerner Grey Award.
