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Temporal range: Middle Triassic to Recent
An intact fossil shell of Exogyra flabellata (Owl Creek Formation, Late Cretaceous, Ripley, Mississippi), held in a human hand
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Ostreoida
Superfamily: Ostreoidea
Family: Gryphaeidae
Vyalov, 1936

See text

Praeexogyra hebridica from the Frome Clay (Bathonian, Middle Jurassic) of Langton Herring, Dorset, England.

The Gryphaeidae, common name the foam oysters or honeycomb oysters, are a family of marine bivalve mollusks, and are a kind of true oyster. This family of bivalves is very well represented in the fossil record, 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.[1]


Genera and species within this family are divided into three subfamilies, Exogyrinae, Gryphaeinae and Pycnodonteinae. Both Exogyrinae and Gryphaeinae are completely extinct. Only four genera Hyotissa, Parahyotissa, Pycnodonte and Neopycnodonte in the subfamily Pycnodonteinae have extant species.[2]

Genera and species[edit]

Genera and species within the family Gryphaeidae include: Family Gryphaeidae Vialov, 1936 (some genera also known as Devil's toenails)


  1. ^ Jocelyne Martin; Gérard Paulmier (3 February 2011). Les invertébrés marins du golfe de Gascogne à la Manche orientale. Editions Quae. p. 82. ISBN 978-2-7592-0107-5. 
  2. ^ The Paleobiology Database Gryphaeidae entry accessed on 6 February, 2011