Progempylus edwardsi

Progempylus edwardsi

Casier, 1966

Common name Snake mackerel
Fossil group Bony Fish
Order Scombriformes
Family Gempylidae
Genus Progempylus
Taxonomic status Accepted
Geological age Ypresian

Summary

Progempylus edwardsi was a snake-mackerel relative and a specialised marine predator in the London Clay fauna. Its skull is long and low, with an extended jaw carrying sharp, backward-curved teeth. This is direct evidence for a grasping predatory feeding apparatus suited to slippery prey such as fishes or cephalopods, although the exact diet is not preserved.

Modern anatomical work places Progempylus within the broader gempylid grade of trichiuroid fishes. The long frontals and slender head show a very different predatory design from the compact skulls of many other early scombriforms, and suggest an active fish operating in the open water or above the seabed.

Quick Identification

Look for: a long, low and slender trichiuroid skull with extended jaws bearing sharp posteriorly curved teeth; the frontals are long and relatively flat, and the known type skull lacks a conspicuous ossified sclerotic ring.

Diagnostic Features

  • Neurocranium is long and low with a distinctly slender overall profile.
  • Frontals are elongate and relatively flat along the dorsal skull roof.
  • Jaws carry long, sharp teeth that curve posteriorly.
  • Mouth extends far back beneath the orbital region, producing a long gape.
  • Known holotype does not show a strongly ossified sclerotic ring 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