Langton Herring Praeexogyra hebridica var elongata Frome Clay Bathonian

Liostrea strigilecula Mid Jurassic SW Utah

The Gryphaeidae,

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

the foam oysters or honeycomb oysters, are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of marine

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s. This family of bivalves is very well represented in the

fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

, however the number of living species is very few. All species have shells cemented to a substrate. Shells are considered brittle, inequivalve, with the left, lower (cemented) valve convex and the right (upper, non-cemented) valve flat or slightly concave.

Subfamilies

Genera and species within this family are divided into three subfamilies, Exogyrinae, Gryphaeinae and Pycnodonteinae. Both Exogyrinae and Gryphaeinae are completely extinct. Only two genera '' Hyotissa'' and ''

Neopycnodonte ''Neopycnodonte'' is a genus of marine (ocean), marine bivalve molluscs belonging to the Family (biology), family Gryphaeidae. This genus is very well represented in the fossil record, however the number of living species is very few. Fossil spe ...

'' in the subfamily Pycnodonteinae have

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

species.

Genera and species

Genera and species within the family Gryphaeidae include: Family Gryphaeidae Vialov, 1936 (some genera also known as Devil's toenails) *Subfamily †Exogyrinae Vialov, 1936 **Genus †'' Aetostreon'' Bayle, 1878 **Genus †'' Amphidonte'' Fischer von Waldheim, 1829 **Genus †'' Costagyra'' Vialov, 1936 **Genus †''

Exogyra ''Exogyra'' is an extinct genus of fossil marine oysters in the family Gryphaeidae, the foam oysters or honeycomb oysters. These bivalves grew cemented by the more cupped left valve. The right valve is flatter, and the beak is curved to one si ...

'' Say, 1820 **Genus †'' Fluctogyra'' Vialov, 1936 **Genus †'' Gryphaeostrea'' Conrad, 1865 **Genus †'' Gyrostrea'' Mirkamalov, 1963 **Genus †'' Ilymatogyra'' Stenzel, 1971 **Genus †'' Nanogyra'' Beurlen, 1958 **Genus †'' Nutogyra'' Vialov, 1936 **Genus †'' Planospirites'' Lamarck, 1801 **Genus †'' Vultogryphaea'' Vialov, 1936 *Subfamily †Gryphaeinae Vialov, 1936 **Genus †'' Africogryphaea'' Freneix, 1963 **Genus †'' Deltoideum'' Rollier, 1917 **Genus †''

Gryphaea ''Gryphaea'', one of the genera known as devil's toenails, is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae. These fossils range from the Triassic period to the middle Paleogene period, but are mostly restric ...

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolog ...

, 1801 **Genus †'' Liostrea'' DouvillŽ, 1904 **Genus †'' Pernostrea'' Munier-Chalmas, 1864 **Genus †'' Praeexogyra'' Charles, 1952 *Subfamily Pycnodonteinae Stenzel, 1959 **Genus †'' Gigantostrea'' (Sacco, 1897) **Genus '' Hyotissa'' Stenzel, 1971 **Genus †'' Labrostrea'' Vialov, 1936 **Genus ''

'' Stenzel, 1971 **Genus †''

Pycnodonte ''Pycnodonte'' is a genus of extinct oysters, fossil marine bivalve mollusks in the family Gryphaeidae, the foam oysters or honeycomb oysters. Shells of species in this genus are found around the world in fossil shell beds from the Valanginian ...

'' (Fischer von Waldheim, 1835) **Genus †'' Texigryphaea'' Stenzel, 1959 *Subfamily ''

Incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' ** Genus †'' Rhynchostreon'' Bayle, 1878

References

Extant Early Triassic first appearances Bivalve families {{bivalve-stub