Spinosuchus

Spinosuchus (meaning "spined crocodile") is an extinct genus of trilophosaurid allokotosaur from the Late Triassic of Texas, southern United States. It has been assigned to a variety of groups over its history, from coelophysid dinosaur to pseudosuchian to uncertain theropod dinosaur and to Proterosuchidae. This uncertainty is not unusual, given that it was only known from a poorly preserved, wall-mounted, partial vertebral column of an animal that lived in a time of diverse, poorly known reptile groups. However, newly collected material and recent phylogenetic studies of early archosauromorphs suggest that is represents an advance trilophosaurid very closely related to Trilophosaurus.

In 1922, Ermine Cowles Case described a partial vertebral column (UMMP 7507) he'd discovered in 1921 from the Tecovas Member of the Carnian-age Upper Triassic Dockum Formation of Crosby County, Texas, as Coelophysis sp. (Coelophysis at that time also being poorly known). He considered it to be about 2.5 meters (8.5 ft) long. Additional material was referred to it, including a femur (UMMP 3396), an ilium (UMMP 8870), and a basicranium (UMMP 7473). These additional remains have since been recognized as belonging to a variety of other Triassic animals, all of which were poorly known or unknown at the time: the femur to an aetosaur, possibly Desmatosuchus, the ilium to a herrerasaurid, either Chindesaurus or Caseosaurus, depending on the taxonomic authority, and the basicranium to the rauisuchian Postosuchus.