Scombramphodon crassidens

Scombramphodon crassidens

Woodward, 1901

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

Summary

Scombramphodon crassidens was a predatory mackerel relative with a strongly differentiated two-rowed dentition. Tiny outer teeth lined the jaw margin while much larger, broad-based inner teeth provided the main gripping force. The enlarged teeth are heavily striated and indicate a fish capable of seizing substantial prey rather than filtering or nibbling small food items.

The exact prey is not preserved, but other fishes and mobile marine animals are a reasonable interpretation from the feeding apparatus. The species shows that early Eocene scombrids included robust-toothed predators alongside more lightly built mackerel-like forms.

Quick Identification

Look for: a scombrid jaw with two sharply different tooth rows — an outer line of small pointed teeth and an inner line of much larger, stout, broad-based teeth with strong vertical striations on the crown base.

Diagnostic Features

  • Jaw bears two distinct functional tooth rows.
  • Outer tooth row consists of small, sharp conical teeth.
  • Inner row contains much larger, robust teeth with broad bases.
  • Large inner teeth carry conspicuous longitudinal or vertical basal striations.
  • Enlarged teeth are more massive and less laterally compressed than the fine outer series.

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

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