Palaeorhincodon dartevellei
Palaeorhincodon dartevellei
Summary
Palaeorhincodon dartevellei was an early member of the whale-shark family, a lineage represented today only by the enormous plankton-feeding whale shark. Its fossil teeth are extremely small, showing that the teeth themselves played a much less forceful feeding role than those of large predatory lamniforms.
Its relationship to modern whale sharks makes planktivory or feeding on very small pelagic prey a plausible ecological interpretation, but the complete filtering apparatus of the animal is not preserved and the exact feeding mechanism cannot be demonstrated from teeth alone.
The species is therefore important as evidence for the early history of the whale-shark lineage rather than as proof of a modern whale-shark lifestyle. It shows that specialised orectolobiform sharks with greatly reduced teeth were already present in early Eocene seas.
Quick Identification
Look for: an extremely small tooth with a narrow central point that leans strongly backwards. There are usually one or two tiny points on each side, while the root is broad and roughly heart-shaped with a deep groove down its centre.
Diagnostic Features
- Main cusp is narrow and strongly inclined backwards.
- Usually one pair of small pointed lateral cusplets occurs, with a second pair possible on some teeth.
- Crown surface and cutting edges are smooth and unserrated.
- A short rounded central projection occurs at the front of the crown base.
- Root is broad, two-lobed and roughly heart-shaped, divided by a deep central groove.
Fossil Details
Recorded Fossil Sites
London Clay Formation
References
- Rayner, D.; Mitchell, T.; Rayner, M. (2009). London Clay Fossils of Kent and Essex. 228 pp.. Medway Fossil and Mineral Society, Rochester, Kent View reference
- Ward, D.J. (1980). The distribution of sharks, rays and chimaeroids in the English Palaeogene. Tertiary Research, 3(1), 13–19 View reference