Wetherellus cristatus

Wetherellus cristatus

Casier, 1966

Common name Mackerel / tuna
Fossil group Bony Fish
Order Scombriformes
Family Scombridae
Genus Wetherellus
Taxonomic status Accepted
Geological age Ypresian

Summary

Wetherellus cristatus was a mackerel-like predatory fish represented by three-dimensional London Clay skulls. The jaw carried two rows of small pointed teeth, while the broad skull roof was strongly ornamented and the eye supported by a large ossified ring. This combination indicates an active, visually oriented fish taking relatively small mobile prey rather than using a crushing dentition.

Modern revision has brought several historically separate London Clay skull forms into W. cristatus, revealing variation in head proportions within the species. The broad cranium and double tooth row provide a useful picture of a distinctive early scombrid feeding and sensory arrangement.

Quick Identification

Look for: a broad scombrid skull with a large sclerotic ring, strong frontal striations radiating from central points and a double row of small fine teeth along the jaws.

Diagnostic Features

  • Frontals carry conspicuous striations radiating outward from central areas.
  • Skull is broad through the orbital and posterior cranial regions.
  • Jaws bear two rows of small, fine pointed teeth.
  • Anterior ethmoid margin is only shallowly emarginate rather than deeply forked.
  • Sclerotic ring is large and strongly ossified around the orbit.

Fossil Details

Preservation
London Clay fish skulls are commonly incomplete, compressed, pyritised or enclosed in concretions. Thin cranial margins and projecting processes are easily lost, and separated bones can be difficult to orient; species-level identification is strongest when several adjoining diagnostic bones are preserved together.

Recorded Fossil Sites

No fossil-site occurrences have yet been recorded for this species.

References

  • Casier, E. (1966). Faune ichthyologique du London Clay. 496 pp.. Trustees of the British Museum (Natural History), London View reference
  • Friedman, M.; Beckett, H. T.; Close, R. A.; Johanson, Z. (2016). The English Chalk and London Clay: two remarkable British bony fish Lagerstätten. Geological Society, London, Special Publications, 430(1), 165–200. Geological Society of London, London View reference
  • Monsch, K. A. (2005). Revision of the scombroid fishes from the Cenozoic of England. Transactions of the Royal Society of Edinburgh: Earth Sciences, 95(3–4), 445–489 View reference
Last Reviewed
20 August 2026 Reviewed by Sam Harris