# Exogyra

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***Exogyra*** is an extinct [genus](/source/Genus) of marine [oysters](/source/Ostreoida) that belongs to the family [Gryphaeidae](/source/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](/source/Substrate_(biology)) in warm seas[citation needed] during the [Jurassic](/source/Jurassic) and [Cretaceous](/source/Cretaceous) periods.[2]

## Taxonomy

The former [subgenus](/source/Subgenus) *Exogyra* (*[Aetostreon](/source/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* (subgenus *Exogyra*) (Say, 1820)**

- *Exogyra africana* Say, 1820[5]
- *Exogyra aquillana* Stephenson, 1953
- *Exogyra arietina* [Roemer](/source/Ferdinand_von_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](/source/Hil%C3%B3_Formation), [Tolima](/source/Tolima_Department), [Macanal](/source/Macanal_Formation) and [Chipaque Formations](/source/Chipaque_Formation), [Eastern Ranges](/source/Cordillera_Oriental_(Colombia))),[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

1. ["Evolution of *Exogyra plexa*"](https://web.archive.org/web/20080326192109/http://crnmac1.physics.uiowa.edu/fossils/oysters/ilymatogyra/Exogyra-plexa.html). Archived from [the original](http://crnmac1.physics.uiowa.edu/fossils/oysters/ilymatogyra/Exogyra-plexa.html) on 26 March 2008. Retrieved 25 March 2008.

1. [*Exogyra*](https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=16655) at [Fossilworks](/source/Fossilworks).org

1. ["†*Exogyra (Aetostreon)* Bayle 1878"](https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=118251). *Paleobiology Database*. Fossilworks. [Archived](https://web.archive.org/web/20211213054834/http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=118251) 13 December 2021 at the Wayback Machine. Retrieved 17 December 2021.

1. Pugaczewska, Halina (1975). ["Neocomian oysters from Central Poland"](http://www.app.pan.pl/archive/published/app20/app20-047.pdf). *Acta Palaeontologica Polonica*. **20** (1): 47–72.

1. [*Exogyra africana*](http://zipcodezoo.com/Animals/E/Exogyra_africana/)

1. Roemer, F. (1849). Texas mit besonderer Rücksicht auf deutsche Auswanderung und die physischen Verhältnisse des Landes nach eigener Beobachtung. A. Marcus.

1. [*Exogyra davidsoni*](https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=304725) at [Fossilworks](/source/Fossilworks).org

1. [*Exogyra*](http://fossilsofnj.com/invertebrates/exogyra.htm)

1. [Lake.P.](/source/Philip_Lake), and [Rastall.R.H.](/source/Robert_Heron_Rastall), (1913), *A Text Book of Geology*, 2nd edition, London: Edward Arnold's Geological series Page 426 and 436

1. [*Exogyra praevirgula*](https://translate.google.com/translate?hl=en&sl=fr&u=http://science.mnhn.fr/all/list%3FspecificEpithet%3Dpraevirgula%26genus%3DExogyra&prev=search)

1. ["Global Names Index"](https://web.archive.org/web/20141106082913/http://gni.globalnames.org/name_indices/98855151/name_index_records). Archived from [the original](http://gni.globalnames.org/name_indices/98855151/name_index_records) on 6 November 2014. Retrieved 5 November 2014.

1. Ivanov. M., Hrdlickova. S., and Gregorova. R., (2005), The Complete Encyclopedia of Fossils, 3rd. ed., Lisse: Rebo International, page 133

1. Piraquive et al., 2011, p. 204

1. 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](/source/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"](https://web.archive.org/web/20170330091900/http://www.bdigital.unal.edu.co/24942/1/22167-87412-2-PB.pdf), *[Geología Colombiana](/source/Geolog%C3%ADa_Colombiana)*. **36**: 197–216, archived from [the original](http://www.bdigital.unal.edu.co/24942/1/22167-87412-2-PB.pdf) on 30 March 2017, retrieved 2017-08-04

## Further reading

- National Audubon Society Field Guide to North American Fossils

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Adapted from the Wikipedia article [Exogyra](https://en.wikipedia.org/wiki/Exogyra) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Exogyra?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.