Paraorthacodus nerviensis
Late Cretaceous (Santonian)
Tyk-Butak, Kazakhstan
Beautiful 8mm x 10mm shark tooth

Paraorthacodus is an extinct genus of shark belonging to the extinct family, Paraorthacodontidae. It is known from rare skeletons in the same limestone as the ancient bird, Archaeopteryx, in the Late Jurassic of Germany but it is usually found as rare isolated teeth at its known localities (Early Jurassic to Late Paleocene).

This specimen is unusually well-preserved. Most teeth are missing at least part of a lateral cusplet.

For a full discussion of these strange sharks see: Klug, S., Kriwet, J., Boettcher, R., Schweigert, G., & Dietl, G. (2009). Skeletal anatomy of the extinct shark Paraorthacodus jurensis (Chondrichthyes; Palaeospinacidae), with comments on synechodontiform and palaeospinacid monophyly. Zoological Journal of the Linnean Society, 157(1), 107-134.