Campylostoma matutiforme

Campylostoma matutiforme

Bell, 1858

Common name Crab
Fossil group Crustaceans
Order Decapoda
Family Cenomanocarcinidae
Genus Campylostoma
Taxonomic status Accepted
Geological age Ypresian

Representative Specimens

Selected reference specimens illustrating this species from different geological units and fossil sites.

Identification Examples

Choose a fossil site to view photographed reference specimens.

Summary

Campylostoma matutiforme was a compact true crab living on the London Clay seabed. Its sturdy body suggests a bottom-dwelling animal that probably searched the sediment for small prey and edible remains, much as many modern marine crabs do.

It formed part of a surprisingly varied Eocene crab fauna in which different species occupied slightly different feeding and hiding niches. A crab like Campylostoma would have been both predator and prey: feeding on smaller animals while itself being vulnerable to fish, sharks and larger crustaceans.

Quick Identification

Look for: a compact, rounded and arched crab carapace with clearly divided dorsal regions and a distinctive cenomanocarcinid outline; retain worn central fragments at a broader crab identification.

Diagnostic Features

  • Carapace compact, rounded and distinctly arched in profile.
  • Dorsal regions are separated by clear grooves and swellings.
  • Lateral margins form a short, compact outline rather than an elongate raninid form.
  • Surface relief is stronger than in many flattened swimming crabs.
  • Species-level identification uses the full carapace outline and regional pattern; the historical spelling mutatiforme is not a separate taxon.

Fossil Details

Typical size
Carapace centimetre-scale; a secure species-wide range is not established.
Fossil material
Carapace, Claw / Chela
Preservation
Compression may reduce the characteristic arched profile, and breakage along the margins can remove useful outline characters. Worn surfaces may also weaken the regional grooves.

Similar Species

Recorded Fossil Sites

References

  • J. S. H. Collins; C. J. T. Mellish; A. J. Ross; P. R. Crabb; S. K. Donovan. (2020). A guide to the fossil Decapoda (Crustacea: Axiidea, Anomura, Brachyura) of the British Isles. Proceedings of the Geologists' Association, 131(1), 19–50 View reference
  • Thomas Bell. (1857). A monograph of the fossil malacostracous Crustacea of Great Britain. Part I. Crustacea of the London Clay. Monograph of the Palaeontographical Society, 10, i–viii, 1–44. Palaeontographical Society, London View reference
Last Reviewed
16 August 2026 Reviewed by Sam Harris