Argillichthys toombsi

Argillichthys toombsi

Casier, 1966

Common name Grinner / lizardfish
Fossil group Bony Fish
Order Aulopiformes
Family incertae sedis
Genus Argillichthys
Taxonomic status Accepted
Geological age Ypresian

Summary

Argillichthys toombsi was an aulopiform teleost from the London Clay marine fauna. Its skull combines a relatively low cranial profile with robust jaws and an ossified eye ring, indicating a visually oriented predatory fish. Aulopiforms include many active predators of fishes and other nekton, and a similar feeding role is a reasonable interpretation for Argillichthys, although its exact prey is not directly known.

The species is represented mainly by three-dimensional cranial material from concretions. These fossils preserve the feeding apparatus and orbital region particularly well, providing a picture of an animal built around a sizeable gape and strong grasping dentition rather than crushing or grazing structures.

Quick Identification

Look for: a low, relatively flat skull with a conspicuous sclerotic ring and strong jaws bearing robust pointed teeth; the combination of a broad orbital region and substantial upper and lower jaw bones is especially useful in complete cranial material.

Diagnostic Features

  • Skull roof is relatively low and flattened dorsoventrally.
  • Orbit contains a well-ossified sclerotic ring.
  • Upper jaw carries robust pointed teeth rather than a pavement of crushing teeth.
  • Lower jaw is similarly strongly toothed and built for grasping.
  • Orbital opening is large relative to the depth of the preserved cranium.

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
Last Reviewed
20 August 2026 Reviewed by Sam Harris