Ostrea bellovacina

Ostrea bellovacina

Lamarck, 1806

Common name Oyster
Fossil group Molluscs
Order Ostreida
Family Ostreidae
Genus Ostrea
Taxonomic status Accepted
Geological age Thanetian and Ypresian

Summary

Ostrea bellovacina was a sessile oyster with two unequal calcitic valves. Like living oysters, it attached one valve to a firm object and filtered suspended food particles from the water with its gills.

Its irregular shell could change shape as it grew against the substrate or neighbouring shells, so hinge and shell construction are more useful than outline alone.

Quick Identification

Look for: a thick, irregular oyster valve with a deep attached lower valve, a flatter opposing valve, layered shell growth and a simple toothless hinge.

Diagnostic Features

  • Shell strongly inequivalve, with one valve typically deeper and more convex than the other.
  • Outline irregular and variable rather than consistently symmetrical.
  • Shell thick and built from conspicuous laminated calcitic layers.
  • Hinge lacks the interlocking cardinal teeth seen in many clams.
  • Concentric growth lamellae dominate the exterior rather than regular radial cockle-like ribs.

Fossil Details

Typical size
Commonly several centimetres across; large valves can approach about 80 mm.
Fossil material
Shell, Internal Mould / Cast
Preservation
The thick calcitic valves are relatively robust, but valve margins and projecting growth lamellae commonly chip or abrade. Detached valves may be incomplete, and heavy wear can make the original attachment area difficult to recognise.

Similar Species

Recorded Fossil Sites

Reculver Sand Member

Thanet Formation
Confirmed
Reculver

Synonyms & Previous Names

Ostrea (Bellostrea) bellovacina

References

  • Rundle, A. J. (1970). Report of a Field Meeting to Abbey Wood, Kent. Tertiary Times, 1, 20–23 View reference
  • Ward, D.J. (1978). The Lower London Tertiary (Palaeocene) succession of Herne Bay, Kent. Report of the Institute of Geological Sciences. Institute of Geological Sciences View reference
Last Reviewed
22 August 2026 Reviewed by Sam Harris