Abstract

Deinosuchus is a lineage of giant (≥10 m) Late Cretaceous crocodylians from North America. These were the largest semiaquatic predators in their environments and are known to have fed on large vertebrates, including contemporaneous terrestrial vertebrates such as dinosaurs. Fossils have been found in units of Campanian age from northern Mexico to Montana in the west and Mississippi to New Jersey in the east. Three species have been named, and recent consensus suggests that they represent a single, widely ranging species. The authors studied newly collected material from western Texas and increased sampling from throughout North America to review species-level systematics of Deinosuchus and help refine its phylogenetic placement among crocodylians. Deinosuchus from eastern and western North America can be consistently differentiated and represent different species. A phylogenetic study is conducted including new character states. This work reinforces the identity of the ‘terror crocodile’ as an alligatoroid. Reference to the holotypes indicates that the generic name holder, Deinosuchus hatcheri, is extremely incomplete. As a result, the three known species of Deinosuchus cannot be differentiated. To ensure nomenclatural stability, the type species for Deinosuchus should be transferred to Deinosuchus riograndensis, a species known from multiple mostly complete individuals. Additionally, Deinosuchus rugosus is based on a holotype that is not diagnostic, and a new species, Deinosuchus schwimmeri, is named to encompass some specimens formerly assigned to D. rugosus.