Serranopsis londinensis

Serranopsis londinensis

Casier, 1966

Common name Perch-like fish
Fossil group Bony Fish
Order Perciformes
Family incertae sedis
Genus Serranopsis
Taxonomic status Taxonomically Uncertain
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

Serranopsis londinensis is a percomorph fish from the London Clay whose exact family position remains uncertain. The skull is laterally compressed and bears a high, thick supraoccipital crest, indicating a deep-headed acanthomorph. Although it was historically compared with serranid-type fishes, current uncertainty means that a sea-bass-style ecology should not be assumed without qualification.

The preserved cranium suggests a substantial marine predator or generalist, but the available material does not securely establish diet. Its main significance lies in documenting a distinctive high-crested percomorph skull within the early Eocene radiation of acanthomorph fishes.

Quick Identification

Look for: a laterally compressed percomorph skull with a very large thick supraoccipital crest rising from the rear of the skull roof; unlike some high-headed London Clay fishes, the known material lacks a conspicuous ossified sclerotic ring.

Diagnostic Features

  • Supraoccipital crest is large, thick and strongly elevated.
  • Neurocranium is laterally compressed and high in profile.
  • Posterior dorsal skull rises steeply into the crest.
  • Sclerotic ring is not conspicuously ossified in the known material.
  • Anterior skull narrows from the deep posterior cranium toward the snout.

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
Last Reviewed
10 August 2026 Reviewed by Sam Harris