Pterothrissus angulatus
Pterothrissus angulatus
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
Recorded Fossil Sites
London Clay Formation
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