Ptychodus

Ptychodus is a genus of hybodontiform sharks.[1] As well as a genus of durophagous (shell-crushing) sharks from the Late Cretaceous.[2] Fossils of Ptychodus teeth are found in plenty in many of the Late Cretaceous marine sediments.[3] There are many species among the Ptychodus that have been uncovered on all the continents around the globe.[3] Such species are Ptychodus mortoni, P. decurrens, P. marginalis, P. mammillaris, P. rugosus and P. latissimus to name a few. They died out approximately 85 million years ago in the Western Interior Sea, where a majority of them were found.[2] A recent publication found that Ptychodus are classified as neoselachian versus hybodont or batoid. [4] [5]