Exogyra

Exogyra is an extinct genus of fossil marine oysters in the family Gryphaeidae, the foam oysters or honeycomb oysters.[1] These bivalves were cemented by the more cupped left valve. The right valve is flatter, and the beak is curved to one side. Exogyra lived on solid substrates in warm seas during the Jurassic and Cretaceous periods.[2]

Exogyra
Temporal range:
Exogyra flabellata
(Owl Creek Formation, Late Cretaceous, Mississippi)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Ostreida
Family: Gryphaeidae
Genus: †Exogyra
Say, 1820
Species

See text

Taxonomy

The former subgenus Exogyra (Aetostreon) Bayle, 1878,[3] is sometimes considered a separate genus due to a lack of the fine set of parallel ribs (chomata) separated by pits on the inner surface of the valves (which is present in the nominate subgenus).[4]

Species
Exogyra costata, Prairie Bluff Chalk Formation (Maastrichtian); Starkville, Mississippi
Exogyra (subgenus Exogyra) (Say, 1820)
  • Exogyra africana Say, 1820[5]
  • Exogyra aquillana Stephenson, 1953
  • Exogyra callophyla Ihering, 1903
  • Exogyra cancellata Stephenson, 1914
  • Exogyra clarki Shattuck, 1903
  • Exogyra columbella Meek, 1876
  • Exogyra contorta Eichwald, 1868
  • Exogyra costata Say, 1971
  • Exogyra davidsoni Whidborne, 1883 [6]
  • Exogyra erraticostata Stephenson[7]
  • Exogyra fimbriata Conrad, 1855
  • Exogyra flabellata (Goldfuss, 1833)
  • Exogyra ganhamoroba Maury, 1936
  • Exogyra guadalupae Whitney, 1937 (thesis)
  • Exogyra haliotoidea Maury, 1936
  • Exogyra laevigata J. de C. Sowerby, 1829 [8]
  • Exogyra laeviuscula Roemer, 1849
  • Exogyra lancha Stoyanow, 1949
  • Exogyra levis Stephenson, 1952
  • Exogyra mutatoria White, 1887
  • Exogyra paupercula Cragin, 1893
  • Exogyra plexa Cragin, 1893
  • Exogyra potosina Castillo and Aguilera, 1895
  • Exogyra ponderosa Roemer, 1852
  • Exogyra praevirgula Douville & Jourdy, 1924[9][10]
  • Exogyra quitmanensis Cragin, 1893
  • Exogyra sergipensis Maury, 1936
  • Exogyra sigmoidea Reuss, 1844[11]
  • Exogyra solea Muller, 1910
  • Exogyra upatoiensis Stephenson, 1914
  • Exogyra whitneyi Bose, 1910
  • Exogyra woolmani Richards, 1947

Distribution

Fossils of Exogyra have been found in:[2]

Jurassic

Afghanistan, Chile, China, Eritrea, Ethiopia, France, Germany, India, Kenya, Poland, Portugal, Somalia, Spain, Tanzania, the United Kingdom, and Yemen.

Cretaceous

Afghanistan, Algeria, Argentina, Brazil, Bolivia, Canada (British Columbia), Bulgaria, Chile, Colombia (Hiló Formation, Tolima, Macanal and Chipaque Formations, Eastern Ranges),[12][13] Cuba, the Czech Republic, Egypt, Ethiopia, France, Germany, Greenland, Hungary, India, Iran, Italy, Jordan, Lebanon, Libya, Madagascar, Mexico, Morocco, Mozambique, New Zealand, Nigeria, Oman, Pakistan, Peru, Poland, Portugal, Serbia and Montenegro, Slovakia, South Africa, Spain, Sweden, Switzerland, Tanzania, Trinidad and Tobago, Tunisia, Turkey, USSR, Ukraine, the United Kingdom, United States (Alabama, Arizona, Arkansas, California, Colorado, Delaware, Georgia, Maryland, Minnesota, Mississippi, Missouri, Montana, New Jersey, New Mexico, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Utah, Wyoming), Venezuela, and Yemen.

References
  1. "Evolution of Exogyra plexa". Archived from the original on 26 March 2008. Retrieved 25 March 2008.
  2. Exogyra at Fossilworks.org
  3. "†Exogyra (Aetostreon) Bayle 1878". Paleobiology Database. Fossilworks. Retrieved 17 December 2021.
  4. Pugaczewska, Halina (1975). "Neocomian oysters from Central Poland" (PDF). Acta Palaeontologica Polonica. 20 (1): 47–72.
  5. Exogyra africana
  6. Exogyra davidsoni at Fossilworks.org
  7. Exogyra
  8. Lake.P., and Rastall.R.H., (1913), A Text Book of Geology, 2nd edition, London: Edward Arnold's Geological series Page 426 and 436
  9. Exogyra praevirgula
  10. Global Names Index
  11. Ivanov. M., Hrdlickova. S., and Gregorova. R., (2005), The Complete Encyclopedia of Fossils, 3rd. ed., Lisse: Rebo International, page 133
  12. Piraquive et al., 2011, p. 204
  13. Acosta & Ulloa, 2002, p. 54

Bibliography

Further reading
  • National Audubon Society Field Guide to North American Fossils


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