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^{[citation needed]} during the Jurassic and Cretaceous periods.^[2]

Exogyra Temporal range: Jurassic–Cretaceous PreꞒ Ꞓ O S D C P T J K Pg N
Exogyra flabellata (Owl Creek Formation, Late Cretaceous, Mississippi)
Scientific 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 arietina Roemer, 1849^[6]
• 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 ^[7]
• Exogyra erraticostata Stephenson^[8]
• 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 ^[9]
• 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, 1849
• Exogyra praevirgula Douville & Jourdy, 1924^[10][11]
• Exogyra quitmanensis Cragin, 1893
• Exogyra sergipensis Maury, 1936
• Exogyra sigmoidea Reuss, 1844^[12]
• Exogyra solea Muller, 1910
• Exogyra texana Roemer, 1849
• 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),^[13][14] Cuba, the Czech Republic, Egypt, Ethiopia, France, Germany, Greenland, Hungary, India, Iran, Israel, 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

• Paleontology portal

1. "Evolution of Exogyra plexa". Archived from the original on 26 March 2008. Retrieved 25 March 2008.
2. Exogyra Archived 13 December 2021 at the Wayback Machine at Fossilworks.org
3. "†Exogyra (Aetostreon) Bayle 1878". Paleobiology Database. Fossilworks. Archived from the original on 13 December 2021. 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. Roemer, F. (1849). Texas mit besonderer Rücksicht auf deutsche Auswanderung und die physischen Verhältnisse des Landes nach eigener Beobachtung. A. Marcus.
7. Exogyra davidsoni Archived 14 December 2021 at the Wayback Machine at Fossilworks.org
8. Exogyra
9. Lake.P., and Rastall.R.H., (1913), A Text Book of Geology, 2nd edition, London: Edward Arnold's Geological series Page 426 and 436
10. Exogyra praevirgula
11. "Global Names Index". Archived from the original on 6 November 2014. Retrieved 5 November 2014.
12. Ivanov. M., Hrdlickova. S., and Gregorova. R., (2005), The Complete Encyclopedia of Fossils, 3rd. ed., Lisse: Rebo International, page 133
13. Piraquive et al., 2011, p. 204
14. Acosta & Ulloa, 2002, p. 54

Bibliography

• Acosta, Jorge E.; Ulloa, Carlos E. (2002), Mapa geológico del Departamento de Cundinamarca 1:250,000 - Memoria Explicativa, Colombian Geological Survey, pp. 1–108
• Piraquive, Alejandro; Díaz, Juan Sebastián; Cuéllar, Tomas; Pardo, Germán; Kammer, Andreas (2011), "Reactivación Neógena de estructuras de rift del Cretácico Temprano asociadas con la Falla de Chámeza, Pajarito, Boyacá (Colombia): evidencias tectónicas y bioestratigráficas" (PDF), Geología Colombiana, 36: 197–216, archived from the original (PDF) on 30 March 2017, retrieved 4 August 2017

Further reading

• National Audubon Society Field Guide to North American Fossils