Somalirhynchia

Somalirhynchia africana is a species of extinct, medium-sized brachiopod, a marine rhynchonellate lampshell in the family Tetrarhynchiidae. It is roughly the size and shape of a 1-inch (25 mm) toy marble, and has about 29 ribs fanning out from the hinge.

Somalirhynchia africana
Temporal range: Late Jurassic, 165–155 Ma
brachial valve
Scientific classification
Kingdom:
Animalia
Phylum:
Brachiopoda
Class:
Rhynchonellata
Order:
Rhynchonellida
Family:
Tetrarhynchiidae
Genus:
† Somalirhynchia
Species:
† S. africana
Binomial name
† Somalirhynchia africana
Weir, 1925

Distribution

Somalirhynchia africana lived during the late Jurassic in the Ethiopian Faunal Province, which consisted of the areas now known as Ethiopia, Somalia, Israel, Jordan, Yemen, Kenya, Madagascar, Saudi Arabia, and Tunisia. It also occurred in India which Kiessling defines as part of the Southwestern Tethys Faunal Province.[1]

Fossils of S. africana are known from the Upper Jurassic of Egypt (Callovian: Jabal al-Magharah/Zohar Formation,[2]), Eritrea, Ethiopia (Callovian: Grande Ilalame;[3] Oxfordian: Mt. Guresu;[3] Early Oxfordian: Mt. Ualinsi;[3] Late Oxfordian: Antalo Limestone;[1] Early Kimmeridgian: Mt. Condudo[3]), India (Callovian: Kachchh[4]), Israel (Middle to Late Callovian: Hamakhtesh Hagadol[5]), Kenya (Oxfordian: Mombasa-Buni, Oxfordian/Kimmeridgian: Baricho[6]), Saudi Arabia (Oxfordian: Shaqra Group/Hanifa Formation,[7] Wadi al Furayshah[8]), Somalia (Callovian: Gerigoan;[9] Callovian/Oxfordian: Daghani, Jirba Range, Madashon, Bihendula, Inda Ad[10][11][12]), Tunisia (Callovian/Kimmeridgian: Tazerdunet/Tataouine;[13] Callovian/Oxfordian: Foum Tataouine, Bir Remtha; Middle/Late Callovian: Ksar Beni Soltane[14]), Yemen (Callovian/Oxfordian: Al Ma'abir, Jebel Billum[15]).[16]

Habitat

During the Upper Jurassic, the fossil locations cited were on continental plates, probably in tropical, shallow, coral seas,[1] where this lampshell lived as a stationary epifaunal suspension feeder.[16]

Description

Somalirhynchia africana has medium sized shells subtriangular in outline, strongly dorsibiconvex with maximum width attained past midlength; beak erect and massive with small hypothyrid pedicle foramen; deltidial plates disjunct. Anterior commissure strongly uniplicate; lateral commissure deflected ventrally; interareas large, somewhat concave. Ventral sulcus originates just past midlength, widening anteriorly into a long tongue with six costae. Dorsal valve high, domelike, with strong median fold with seven costae that begins near midlength and becomes strongly elevated anteriorly.[2]

References
  1. W. Kiessling, D. K. Pandey, M. Schemm-Gregory, H. Mewis, and M. Aberhan. 2011. Marine benthic invertebrates from the Upper Jurassic of northern Ethiopia and their biogeographic affinities. Journal of African Earth Sciences 59:195-214 "Archived copy" (PDF). Archived from the original (PDF) on 2012-04-25. Retrieved 2011-10-14.CS1 maint: archived copy as title (link)
  2. H. R. Feldman, E. F. Owen, and F. Hirsch. 1991. Brachiopods from the Jurassic of Gebel El-Maghara, northern Sinai. American Museum Novitates 3006:1-28)
  3. D. Jaboli. 1959. Fossili Giurassici dell'Harar (Africa Orientale): Brachiopodi, Lamellibranchi e Gasteropodi [Jurassic fossils from Harar (Eastern Africa): brachiopods, lamellibranchs and gastropods]. Missione Geologica dell'Azienda Italiana Petroli (AGIP) nella Dancalia Meridionale e sugli Altipiani Hararini 4(1):3-100
  4. F.T. Fürsich. 2006. (Unpublished data from Kachchh)
  5. H. R. Feldman, E. F. Owen, and F. Hirsch. 2001. Brachiopods from the Jurassic (Callovian) of Hamakhtesh Hagadol (Kurnub Anticline), southern Israel. Palaeontology 44(4):637-658
  6. J. Weir. 1930. Mesozoic Brachiopoda and Mollusca from Mombasa. In M. M. Wood (ed.), Reports on geological collections from the coastlands of Kenya Colony. Monographs of the Geological Department of the Hunterian Museum Glasgow University 4:73-102
  7. J. Manivit, Y.-M. Le Nindre, and D. Vaslet. 1990. Le Jurassique D`Arabie Centrale. Document du BRGM 4(194):25-519
  8. G. A. Cooper. 1989. Jurassic brachiopods of Saudi Arabia. Smithsonian Contributions to Paleobiology 65:1-213
  9. E. Abbate, G. Ficcarelli, C. Pirini Radrizzani, A. Salvietti, D. Torre and A. Turi. 1974. Jurassic sequences from the Somali coast of the Gulf of Aden. Rivista Italiana di Paleontologia e Stratigrafia 80(3):409-478
  10. H. D. Thomas. 1935. Jurassic corals and Hydrozoa, together with a re-description of Astraea caryophylloides Goldfuss. The Mesozoic Palaeontology of British Somaliland, Geology and Palaeontology of British Somaliland, II 23-39
  11. L. R. Cox. 1935. Jurassic Gastropoda and Lamellibranchia. The Mesozoic Palaeontology of British Somaliland, Geology and Palaeontology of British Somaliland, II 148-197
  12. H. M. Muir-Wood. 1935. Jurassic Brachiopoda. The Mesozoic Palaeontology of British Somaliland, Geology and Palaeontology of British Somaliland, II 75-147
  13. G. Dubar. 1967. Brachiopodes Jurassiques du Sahara Tunisien/Jurassic brachiopods from the Tunisian Sahara. Annales de Paléontologie, Invertebres 53:1-71
  14. Holzapfel. 1998. Palökologie benthischer Faunengemeinschaften und Taxonomie der Bivalven im Jura von Südtunesien. Beringeria - Würzburger geowissenschaftliche Mitteilungen (22)1-199
  15. M. K. Howarth and N. J. Morris. 1998. The Jurassic and Lower Cretaceous of Wadi Hajar, southern Yemen. Bulletin of the Natural History Museum (Geology) 54(1):1-32)
  16. Paleobiology Data Base
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