Pycnodus toliapicus
Pycnodus toliapicus
Summary
Pycnodus toliapicus was another pycnodont specialised for crushing resistant prey on or near the seabed. Its splenial tooth plates carry multiple rows of rounded and elongate teeth, forming a broad dental mill rather than a conventional line of pointed jaw teeth. The structure is strong evidence for a diet including hard-shelled invertebrates, though the exact prey species are unknown.
The species demonstrates that durophagous pycnodonts remained part of marine fish communities into the early Eocene. London Clay specimens are primarily dental plates, so the feeding system is much better known than the overall body shape.
Quick Identification
Look for: a thick pycnodont tooth plate with several rows of flattened oval crushing teeth, the central series much larger than the outer rows; the second major row is only about half the size of the largest teeth and marginal crowns may show surface pitting.
Diagnostic Features
- Tooth plate contains multiple parallel rows of rounded to elongate crushing teeth.
- Largest central teeth have broad, nearly flat occlusal surfaces with rounded margins.
- Second principal tooth row has teeth about half the size of the largest series.
- Marginal teeth are smaller, rounder and may show distinct surface pitting.
- Teeth are closely packed on a thick splenial plate built to resist compressive loading.
Fossil Details
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