Paronychodon lacustris Paronychodon

Paronychodon (meaning “beside claw tooth”) is an extinct theropod dinosaur genus. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include “buckets” of teeth from many disparate times and places but no other remains, and should be considered a form taxon.

The type species, named by Edward Drinker Cope in 1876, is Paronychodon lacustris, from the Judith River Formation of Montana, dating to 75 million years ago, during the Campanian stage. The holotype is specimen AMNH 3018. It is a tooth about one centimetre long, elongated, recurved, lacking serrations, possessing low vertical ridges and with a D-shaped cross-section, the inner side being flattened. Cope at first thought the tooth belonged to a plesiosaur, but in the same year realised it represented a carnivorous dinosaur.