Notorynchus serratissimus

Notorynchus serratissimus

(Agassiz, 1843)

Common name Cow shark
Fossil group Sharks & Rays
Order Hexanchiformes
Family Hexanchidae
Genus Notorynchus
Taxonomic status Accepted
Geological age Ypresian

Summary

Notorynchus serratissimus was a sevengill cow shark belonging to an ancient shark lineage that retains more gill slits and a more primitive body organisation than most modern sharks. Its living relatives are large, versatile predators capable of using a broad range of marine habitats.

The lower teeth of N. serratissimus formed long multi-cusped cutting blades. Such a dentition was well suited to slicing flesh and suggests an opportunistic predator taking fishes and other vertebrate prey; scavenging is also plausible by comparison with living cow sharks.

Because the species is known mainly from teeth, its exact size, habitat preferences and behaviour remain uncertain. The dentition nevertheless identifies it as one of the more formidable generalist predators in the early Eocene shark community.

Quick Identification

Look for: a broad lower tooth with a high main cusp followed by several progressively smaller distal cusplets, producing a strongly serrated comb-like profile on a long low root.

Diagnostic Features

  • Lower anterolateral crown has one dominant cusp and a series of distal cusplets.
  • Cusplets form a strongly graded cutting series rather than equal-sized points.
  • Mesial cutting edge of the principal cusp is elongated and blade-like.
  • Root is long, low and continuous beneath the multi-cusped crown.
  • Upper-tooth morphology differs markedly and is less diagnostic in isolation.

Fossil Details

Preservation
The small distal cusplets break easily, and worn specimens may retain only the main cusp and root. Species separation among fossil hexanchids should not rely on an incomplete cusp count.

Similar Species

Recorded Fossil Sites

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. (1979). Additions to the fish fauna of the English Palaeogene. 3. A review of the Hexanchid sharks with a description of four new species. Tertiary Research, 2(3), 111–129 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
Last Reviewed
13 August 2026 Reviewed by Sam Harris