Poposauridae is a family of large carnivorous archosaurs which lived alongside dinosaurs during the Late Triassic. They were around long. Poposaurids are known from fossil remains from North and South America. While originally believed to be theropod dinosaurs (they mirrored the theropods in a number of respects, such as features of the skull and bipedal locomotion), cladistic analysis has shown them to be more closely related to crocodiles.
An early cladistic analysis of crocodylotarsan archosaurs included Poposaurus, Postosuchus, Teratosaurus, and Bromsgroveia within Poposauridae. However, later studies found Teratosaurus to be a rauisuchid. All recent phylogenetic analyses place Postosuchus either as a rauisuchid or a prestosuchid.