Nucula fragilis

Nucula fragilis

Deshayes, 1829

Common name Nut Clam
Fossil group Molluscs
Order Nuculida
Family Nuculidae
Genus Nucula
Taxonomic status Accepted
Geological age Ypresian

Summary

Nucula fragilis was a small nut clam. Nuculids are mobile infaunal deposit feeders that use elongated labial palps to collect organic-rich particles from the sediment.

The shell combines a compact triangular-ovate outline with a taxodont hinge of many small teeth. Fine hinge and margin characters are important because incomplete nuculid valves can look very similar.

Quick Identification

Look for: a small compact triangular-oval valve with a prominent umbo, many tiny taxodont hinge teeth and a mostly smooth exterior marked by fine growth lines.

Diagnostic Features

  • Shell small and compact, triangular-ovate in outline.
  • Umbone distinct and positioned close to the dorsal margin.
  • Hinge bears numerous small taxodont teeth on both sides of the beak.
  • Exterior is smooth to finely sculptured with close concentric growth lines.
  • Inner ventral margin is finely crenulated when well preserved.

Fossil Details

Typical size
Small, generally centimetre-scale or less; no tighter defensible adult range was established in this audit.
Fossil material
Shell, Internal Mould / Cast
Preservation
Small nuculid valves are easily broken or lost during collection. The hinge teeth and finely crenulated margin are especially vulnerable to abrasion, while internal moulds are rarely sufficient for species-level identification.

Similar Species

Recorded Fossil Sites

Synonyms & Previous Names

Nucula (Nucula) fragilis; Nucula levesquei

References

  • Glibert, M.; Van de Poel, L. (1965). Les Bivalvia fossiles du Cénozoique étranger des collections de l’Institut royal des Sciences naturelles de Belgique. I. Palaeotaxodontia et Eutaxodontida. Mémoires de l'Institut royal des Sciences naturelles de Belgique, 77, 112 pp.. Institut royal des Sciences naturelles de Belgique, Bruxelles View reference
  • Pacaud, J.-M. (2007). Nouveautés nomenclaturales et taxonomiques introduites par Alcide d’Orbigny dans le Prodrome (1850, 1852) pour les espèces du Paléocène et de l’Éocène. Geodiversitas, 29(1), 17–85 View reference
  • Wrigley, A. (1931). The Lower Eocene Mollusca of Abbey Wood and of High Halstow, Kent. The Vertebrate Faunas of the English Eocene, 1, 110–112. British Museum (Natural History), London View reference
Last Reviewed
22 August 2026 Reviewed by Sam Harris