Exogyra

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
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Ostreida
Family:	Gryphaeidae
Genus:	† Exogyra Say, 1820
Species
See text

Exogyra is an extinct genus of marine oysters that belongs to the family Gryphaeidae (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]

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 africanaSay, 1820 ^[5]
• Exogyra aquillanaStephenson, 1953
• Exogyra arietina Roemer, 1849 ^[6]
• Exogyra callophylaIhering, 1903
• Exogyra cancellataStephenson, 1914
• Exogyra clarkiShattuck, 1903
• Exogyra columbellaMeek, 1876
• Exogyra contortaEichwald, 1868
• Exogyra costataSay, 1971
• Exogyra davidsoniWhidborne, 1883 ^[7]
• Exogyra erraticostata Stephenson ^[8]
• Exogyra fimbriataConrad, 1855
• Exogyra flabellata(Goldfuss, 1833)
• Exogyra ganhamorobaMaury, 1936
• Exogyra guadalupaeWhitney, 1937 (thesis)
• Exogyra haliotoideaMaury, 1936
• Exogyra laevigataJ. de C. Sowerby, 1829 ^[9]
• Exogyra laeviusculaRoemer, 1849
• Exogyra lanchaStoyanow, 1949
• Exogyra levisStephenson, 1952
• Exogyra mutatoriaWhite, 1887
• Exogyra pauperculaCragin, 1893
• Exogyra plexaCragin, 1893
• Exogyra potosinaCastillo and Aguilera, 1895
• Exogyra ponderosaRoemer, 1849
• Exogyra praevirgulaDouville & Jourdy, 1924 ^{[10] [11]}
• Exogyra quitmanensisCragin, 1893
• Exogyra sergipensisMaury, 1936
• Exogyra sigmoideaReuss, 1844 ^[12]
• Exogyra soleaMuller, 1910
• Exogyra texanaRoemer, 1849
• Exogyra upatoiensisStephenson, 1914
• Exogyra whitneyiBose, 1910
• Exogyra woolmaniRichards, 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, Palestine, 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 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 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