New material of Luperosuchus fractus (Archosauria: Crurotarsi) from the Middle Triassic of Argentina: the earliest known South American "Rauisuchian"

Abstract

"Rauisuchian" archosaurs were some of the largest terrestrial carnivores during the Middle and Late Triassic in Europe, North Africa, Asia, India, and the Americas (Gower, 2000). Despite their worldwide distribution, "rauisuchian" evolutionary history is poorly understood and their taxonomy remains problematic because many taxa were erected on fragmentary, undiagnostic remains, and some characters are convergent with other archosaurs (Nesbitt and Norell, 2006; Nesbitt, 2007). The earliest undoubted ‘rauisuchians’ are Anisian in age and include Bromsgroveia Galton, 1985 from England, Arizonasaurus Welles, 1947 from the U.S.A., and Yarasuchus Sen, 2005 from India. Several Lower Triassic possible ‘rauisuchians’ from Russia would represent the first record of the group if their affinities were confirmed (Gower and Sennikov, 2000). In the Ladinian, there is an increase in taxonomic diversity of ‘rauisuchians,’ which are then well represented in Europe, South America, and Africa (e.g., Krebs, 1965; Gower, 1999). The ‘rauisuchian’ record in South America is particularly diverse ranging from the Ladinian to the Norian, and includes well-preserved, complete specimens of Prestosuchus Huene, 1938 (Brazil), Luperosuchus Romer, 1971, Saurosuchus Reig, 1959, and Fasolasuchus Bonaparte, 1981 (Argentina).