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 con ...

the foam oysters or honeycomb oysters, are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of marine

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

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 ...

, 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 ''Hyotissa'' is a genus of large saltwater oysters, marine (ocean), marine bivalve mollusks in the family Gryphaeidae.MolluscaBase eds. (2021). MolluscaBase. Hyotissa Stenzel, 1971. Accessed through: World Register of Marine Species at: http://ww ...

'' and '' Neopycnodonte'' in the subfamily Pycnodonteinae have

extant Extant or Least-concern species, least concern 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 * Exta ...

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

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species or languages). It is one of the mo ...

Exogyrinae Vialov, 1936 **Genus †'' Aetostreon'' Bayle, 1878 **Genus †'' Amphidonte'' Fischer von Waldheim, 1829 **Genus †'' Costagyra'' Vialov, 1936 **Genus †'' Exogyra'' 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''

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 biolo ...

, 1801 **Genus †''

Liostrea ''Liostrea'' is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae. These fossils range from the early Triassic Period to the Cenomanian Epoch of the late Cretaceous Period and were widely distributed geographically ...

'' DouvillŽ, 1904 **Genus †'' Pernostrea'' Munier-Chalmas, 1864 **Genus †'' Praeexogyra'' Charles, 1952 *Subfamily Pycnodonteinae Stenzel, 1959 **Genus †'' Gigantostrea'' (Sacco, 1897) **Genus ''

'' Stenzel, 1971 **Genus †'' Labrostrea'' Vialov, 1936 **Genus '' Neopycnodonte'' 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 Valanginia ...

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

Incertae sedis or is a term used for a taxonomy (biology), 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