Pterothrissus angulatus

Pterothrissus angulatus

Stinton, 1966

Common name Deep-sea bonefish relative
Fossil group Bony Fish
Order Albuliformes
Family Pterothrissidae
Genus Pterothrissus
Taxonomic status Accepted
Geological age Ypresian

Summary

Pterothrissus angulatus was a deep-sea bonefish relative known from large sagittal otoliths. Living pterothrissids are elongate bottom-associated fishes of deeper marine waters that feed on small benthic and planktonic animals. A similar demersal shelf-to-slope ecology is plausible for the Eocene species, but the London Clay evidence itself is the ear stone rather than the body.

Its otolith is massive and strongly sculpted in profile, with a pronounced predorsal angle and a diagonal sulcus. The size and distinctive geometry make it one of the more striking otolith morphologies in the London Clay fish assemblage.

Quick Identification

Look for: a large, thick, roughly rectangular otolith with a strongly convex inner face, concave outer face, a pronounced predorsal angle and a diagonal sulcus with a broad anterior ostium and narrow posterior cauda.

Diagnostic Features

  • Otolith is large and massive, reaching well over a centimetre in adult specimens.
  • Inner face is strongly convex while the outer face is distinctly concave.
  • Dorsal rim has a deep predorsal angle followed by an expanded postdorsal region.
  • Sulcus runs diagonally across the inner face rather than horizontally.
  • Ostium is broad and opens indistinctly toward the anterodorsal margin, while the cauda is narrow.

Fossil Details

Preservation
London Clay otoliths may be chipped, rounded, dissolved or polished. Damage to the rostrum and antirostrum changes the outline, while abrasion of the inner face can weaken or erase the sulcus; either can make a species-level identification unsafe.

Recorded Fossil Sites

References

  • Steurbaut, E.; Nolf, D. (1988). Ypresian teleost otoliths from Belgium and northwestern France. Bulletin de la Société belge de Géologie, 97(3–4), 321–347 View reference
  • Stinton, F. C. (1966). Fish otoliths from the London Clay. Faune ichthyologique du London Clay, 404–464. British Museum (Natural History), London View reference
Last Reviewed
15 August 2026 Reviewed by Sam Harris