Wikipedia
Rauisuchidae is a group of large (up to 6 meters or more) predatory Triassic archosaurs.. There is some disagreement over which genera should be included in the Prestosuchidae, which in Rauisuchidae, and which in the Poposauridae, and indeed whether these should even be thought of as separate families. Rauisuchids occurred throughout much of the Triassic, and may have first occurred in the Early Triassic if some archosaurian taxa such as Scythosuchus and Tsylmosuchus are considered to be within the family.
An early cladistic analysis of crocodylotarsan archosaurs included Lotosaurus, Fasolasuchus, Rauisuchus, and "the Kupferzell rauisuchid" (later called Batrachotomus) within Rauisuchidae. However, a later study found that Batrachotomus was more closely related to Prestosuchus, and thus was a prestosuchid. In addition, the toothless Lotosaurus has been found to be more closely related to the Ctenosauriscidae, a clade of Dimetrodon-like animals with sails on their backs.
Two genera previously classified as poposaurids, are in fact rauisuchids. These include Teratosaurus and Postosuchus.