Rauisuchidae is a group of large (up to or more) predatory

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avia ...

s. There is some disagreement over which genera should be included in Rauisuchidae and which should be in the related Prestosuchidae and

Poposauridae 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 ...

, and indeed whether these should even be thought of as separate valid families. Rauisuchids occurred throughout much of the Triassic, and may have first occurred in the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is ...

if some archosaurian taxa such as ''

Scythosuchus ''Scythosuchus'' is an extinct genus of rauisuchid. Remains have been found from Olenekian-age Lower Triassic beds in Russia, hence the name meaning 'Scythian crocodile'. The type and only species is ''S. basileus'', described in 1999. ''Scythos ...

'' and ''

Tsylmosuchus ''Tsylmosuchus'' is an extinct genus of potentially dubious ctenosauriscid archosauriform reptile known from Western Russia. Fossils referred to ''Tsylmosuchus'' occurred over a wide area in sediments corresponding to the Induan and Olenekian s ...

'' are considered to be within the family. An early cladistic analysis of crocodylotarsan (

pseudosuchia Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...

s included '' Lotosaurus'', ''

Fasolasuchus ''Fasolasuchus'' is an extinct genus of loricatan. Fossils have been found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina that date back to the Norian stage of the Late Triassic, making it one of ...

'', ''

Rauisuchus ''Rauisuchus'' (meaning "Wilhelm Rau's crocodile") is a genus of extinct archosaurs which lived in what is now the Geopark of Paleorrota ( Santa María Formation), Brazil, during the Late Triassic period (235–228 million years ago). It conta ...

'', and "the Kupferzell rauisuchid" (later called ''

Batrachotomus ''Batrachotomus'' is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. ''Batrachotomus'' was descr ...

'') within Rauisuchidae.Parrish JM. 1993. Phylogeny of the Crocodylotarsi, with reference to archosaurian and crurotarsan monophyly. ''Journal of Vertebrate Paleontology'' 13: 287-308. However, a later study found that ''

'' was a more basal pseudosuchian only slightly more "advanced" than ''

Prestosuchus ''Prestosuchus'' (meaning "Prestes crocodile") is an extinct genus of pseudosuchian in the group Loricata, which also includes '' Saurosuchus'' and '' Postosuchus''. It has historically been referred to as a " rauisuchian", and was the defining ...

''.Gower DJ. 2002. Braincase evolution in suchian archosaurs: evidence from the rauisuchian ''Batrachotomus''. ''Zoological Journal of the Linnean Society'' 136: 49-76. In addition, the toothless ''Lotosaurus'' has been found to be more closely related to the Ctenosauriscidae, a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

of poposauroids with sails on their backs.Nesbitt SJ. 2005. Osteology of the Middle Triassic pseudosuchian archosaur ''Arizonasaurus babbitti''. ''Historical Biology'' 17: 19-47. Two genera previously classified as poposaurids, are in fact rauisuchids. These include '' Teratosaurus''Long RA, Murry PA. 1995. Late Triassic (Carnian and Norian) tetrapods from the Southwestern United States. ''New Mexico Museum of Natural History & Science Bulletin'' 4: 1-254.Galton PM, Walker AD. 1996. ''Bromsgroveia'' from the Middle Triassic of England, the earliest record of a poposaurid thecodontian reptile (Archosauria: Rauisuchia). ''Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen'' 201 (3): 303-325. and '' Postosuchus''.Weinbaum JC, Hungerbühler A. 2007. A revision of ''Poposaurus gracilis'' (Archosauria: Suchia) based on two new specimens from the Late Triassic of the southwestern U.S.A. ''Paläontologische Zeitschrift'' 81(2):131-145.

Genera

References

External links

Taxon Search - Rauisuchidae

- Mikko's Phylogeny Archive.

- Dinosaur Mailing List archives

- Dinosaur Mailing List archives {{Taxonbar, from=Q134295 Early Triassic first appearances Late Triassic extinctions Prehistoric reptile families