''Rauisuchus'' (meaning "Wilhelm Rau's

crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to inclu ...

") is a genus of extinct

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-avian d ...

s 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 contains one species, ''R. tiradentes''.''Rauisuchus''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.orgF. v. Huene. (1942) ''Die fossilen Reptilien des südamerikanischen Gondwanalandes. Ergebnisse der Sauriergrabung in Südbrasilien 1928/29.'' München: C.H. Beck'sche Verlagsbuchhandlung

Discovery and naming

In 1928 or 1929, near the road from Santa Maria to San Jose, Dr. Wilhelm Rau, a German fossil collector working under

Friedrich von Huene Friedrich von Huene, born Friedrich Richard von Hoinigen, (March 22, 1875 – April 4, 1969) was a German paleontologist who renamed more dinosaurs in the early 20th century than anyone else in Europe. He also made key contributions about v ...

, discovered the remains of a

rauisuchid Rauisuchidae is a group of large (up to or more) predatory Triassic archosaurs. There is some disagreement over which genera should be included in Rauisuchidae and which should be in the related Prestosuchidae and Poposauridae, and indeed whethe ...

crocodile. He made the discovery some from the road at a site known as the Zahnsanga, which was likely a ravine or escarpment parallel to the road. The Zahnsanga site was part of the Alemoa Member of the Santa Maria Formation and was found in the uppermost of an layer. von Huene then sent the ''R. tiradentes'' material back to Germany alongside other fossils, including the holotype of '' Prestosuchus chiniquensis''. von Huene (1936) named ''Rauisuchus'' in a list of the Thecodontia,v. Huene, F. (1936). The constitution of the Thecodontia. ''American Journal of Science'' 32:207-217 but no diagnosis or description was given, so it remained a ''nomen dubium'' until being properly described by von Huene (1942). Krebs (1973) described the tarsus of ''R. tiradentes'' and the lectotype was assigned in 1976 and consists of BSPG AS XXV 60–68, 71–100, 105–119 and 121 (the right premaxilla, right postorbital, left squamosal, left jugal, right pterygoid, right nasal, both splenials, left surangular, prearticular and angular, odontoid(?), axis, cervical, dorsal and caudal vertebrae, ribs, chevron bones, right scapulacoracoid, left pubis, right tibia, fibula and astragalus, and body osteoderms).Krebs, B. (1976). Pseudosuchia. In: Kuhn O, ed Handbuch der Paläoherpetologie, Thecodontia. Stuttgart: Gustav Fischer Verlag, 40–98. It is unclear if the lectotype remains belonged to one or two individuals. The specimens found by Rau were eventually re-described by Lautenschlager & Rauhut (2014) and they identified that from Localities 15-17, one or two specimens were found. According to von Huene (1942), 'Find 1025' was assigned to BSPG AS XXV 122 (a partial left maxilla) and 'Find 1020' was assigned to BSPG AS XXV 123 (a cervical vertebra), BSPG AS XXV 124, (a rib fragment), BSPG AS XXV 120 and BSPG, no number (two chevron bone fragments) and BSPG AS XXV 88 (a complete left ilium). Lautenschlager & Rauhut (2014) found that the remains from Locality 15 ('Find 1020') could not be diagnostically assigned to ''Rauisuchus'', and so were removed from the genus. They also noted that von Huene (1942) assigned two more specimens from other localities to ''R. tiradentes'': several isolated teeth, BSPG AS XXV 101 (the proximal end of an ulna) and BSPG AS XXV 102 (a partial metatarsal), but these cannot be confidently assigned to ''R. tiradentes'' as no overlapping material is known. Raiusuchus scale diagram

Description

''Rauisuchus'' possibly grew to a length of and would be high at the hips and it had a weight of around . ''Rauisuchus'' is distinguished from other members of the Rauisuchidae on the basis of a knob-like thickening on the base of the posterior process of the premaxilla, short, ventrally keeled cervicals, lacking postzygodiapophyseal laminae, and elongated caudals with an accessory neural spine and a postspinal lamina.

Classification

''Rauisuchus'' belonged to a group of land-dwelling relatives to

s known as the Rauisuchidae, although it was initially assigned to the Theriodontia in 1936. Rauisuchids were among the top predators of their day, eating other reptiles for food and maybe hunting early dinosaurs. It was placed as the sister taxon to '' Tikisuchus'' and '' Yarasuchus'', forming 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 term, ...

with the two.

References

Rauisuchids Triassic reptiles of South America Triassic Brazil Fossils of Brazil Santa Maria Formation Fossil taxa described in 1936 Taxa named by Friedrich von Huene Prehistoric pseudosuchian genera {{triassic-reptile-stub