Exogyra

Exogyra is an extinct genus of fossil marine oysters in the family Gryphaeidae, the foam oysters or honeycomb oysters. 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.

Taxonomy
The former subgenus Exogyra (Aetostreon) Bayle, 1878, 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).

Species
• Exogyra (subgenus Exogyra) (Say, 1820)

• Exogyra africana Say, 1820

• 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

• Exogyra erraticostata Stephenson

• 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

• 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

• Exogyra quitmanensis Cragin, 1893

• Exogyra sergipensis Maury, 1936

• Exogyra sigmoidea Reuss, 1844

• Exogyra solea Muller, 1910

• Exogyra upatoiensis Stephenson, 1914

• Exogyra whitneyi Bose, 1910

• Exogyra woolmani Richards, 1947

Distribution
Fossils of Exogyra have been found in: Afghanistan, Chile, China, Eritrea, Ethiopia, France, Germany, India, Kenya, Poland, Portugal, Somalia, Spain, Tanzania, the United Kingdom, and Yemen.
 * Jurassic

Afghanistan, Algeria, Argentina, Brazil, Bolivia, Canada (British Columbia), Bulgaria, Chile, Colombia (Hiló Formation, Tolima, Macanal and Chipaque Formations, Eastern Ranges), 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.
 * Cretaceous