Loxoptychodon cuneiformis

Loxoptychodon cuneiformis

(J. Sowerby, 1817)

Common name Clam
Fossil group Molluscs
Order Venerida
Family Cyrenidae
Genus Loxoptychodon
Taxonomic status Accepted
Geological age Ypresian

Summary

Loxoptychodon cuneiformis was a robust cyrenid bivalve, part of a family suited to freshwater and brackish habitats. It probably lived shallowly buried in sand or mud and suspension-fed with its gills.

The shell is relatively thick and wedge-shaped to rounded-triangular. Hinge structure is important for separating it from more delicate cyrenids.

Quick Identification

Look for: a thick wedge-shaped to rounded-triangular clam valve with a prominent umbo, strong concentric growth and a well-developed heterodont hinge.

Diagnostic Features

  • Valve thick and broadly triangular to wedge-shaped.
  • Umbone prominent and raised above the dorsal margin.
  • Exterior dominated by concentric growth lines rather than strong radial ribs.
  • Hinge bears robust cardinal and lateral teeth typical of cyrenids.
  • Shell is more inflated and angular than the thinner, more elongate Tellinocyclas tellinoides.

Fossil Details

Typical size
About 30 mm.
Fossil material
Shell, Internal Mould / Cast
Preservation
Isolated valves are common in fossil cyrenids. Abrasion may smooth the concentric sculpture and break the hinge teeth, so the umbo and hinge should be examined before assigning worn material.

Similar Species

Recorded Fossil Sites

Synonyms & Previous Names

Corbicula cuneiformis; Corbicula (Loxoptychodon) cuneiformis

References

  • MolluscaBase Editorial Board. (2026). MolluscaBase: Loxoptychodon cuneiformis (J. Sowerby, 1817). MolluscaBase View reference
  • Rundle, A. J. (1970). Report of a Field Meeting to Abbey Wood, Kent. Tertiary Times, 1, 20–23 View reference
  • Spijkerman, E.; van Nieulande, F. A. D.; Wesselingh, F. P.; Reich, S.; Tracey, S. (2015). Pourcy (Paris Basin, France): preliminary assessment of an early Eocene NW European tropical coastal environment from molluscs and vertebrate fossils. Cainozoic Research, 15(1–2), 155–180 View reference
Last Reviewed
22 August 2026 Reviewed by Sam Harris