Rauisuchus
Rauisuchus is a genus of extinct archosaurs which lived in what is now the Geopark of Paleorrota, Brazil, during the Late Triassic period. It contains one species, R. tiradentes.
Discovery and naming
In 1928 or 1929, near the road from Santa Maria, [Rio Grande do Sul|Santa Maria] to San Jose, Dr. Wilhelm Rau, a German fossil collector working under Friedrich von Huene, discovered the remains of a rauisuchid 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 named Rauisuchus in a list of the Thecodontia, but no diagnosis or description was given, so it remained a nomen dubium until being properly described by von Huene.
Krebs 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. 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 and they identified that from Localities 15-17, one or two specimens were found. According to von Huene, 'Find 1025' was assigned to BSPG AS XXV 122 and 'Find 1020' was assigned to BSPG AS XXV 123, BSPG AS XXV 124,, BSPG AS XXV 120 and BSPG, no number and BSPG AS XXV 88. Lautenschlager & Rauhut found that the remains from Locality 15 could not be diagnostically assigned to Rauisuchus, and so were removed from the genus. They also noted that von Huene assigned two more specimens from other localities to R. tiradentes: several isolated teeth, BSPG AS XXV 101 and BSPG AS XXV 102, but these cannot be confidently assigned to R. tiradentes as no overlapping material is known.
Description
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 crocodiles 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 with the two.