Prestosuchus (meaning "Prestes' crocodile") is an extinct genus of pseudosuchian in the group Loricata, from the Middle Triassic of Brazil. Prestosuchus is one of the largest and most extensively described early loricatans, known from many specimens including partial skeletons and enormous skulls. All undisputed Prestosuchus fossils are from the lower Santa Maria Formation (Dinodontosaurus assemblage zone) of Rio Grande do Sul, Brazil. The type species, Prestosuchus chiniquensis, was originally named by Friedrich von Huene in 1938, though its original fossils were rather fragmentary compared to later finds. There has been some debate over exactly how many species are contained within Prestosuchus. Some purported Prestosuchus species are at other times regarded as unrelated pseudosuchians, such as Procerosuchus, Schultzsuchus ("Prestosuchus loricatus"), and Stagonosuchus ("Prestosuchus nyassicus"). Alongside relatives such as Saurosuchus and Postosuchus, Prestosuchus has historically been referred to as a "rauisuchian", as well as the defining member of the family Prestosuchidae. The validity of both of these groups is questionable. "Rauisuchia" is now considered a paraphyletic group of large carnivorous pseudosuchians ancestral to crocodylomorphs. Prestosuchidae is polyphyletic in its widest form, though it may retain some utility in a narrower sense centered on Prestosuchus.
History of study
Munich specimens The holotype of Prestosuchus chiniquensis was discovered by Wilhelm Rau alongside the holotype of Rauisuchus tiradentes. Both were found in 1928 or 1929 within the Santa Maria Formation at Paleontological Site Chiniquá, near the city of São Pedro do Sul in Rio Grande do Sul, Brazil. The fossils were shipped back to Germany for study by the German paleontologist Friedrich von Huene. Von Huene named the genus Prestosuchus in 1938 in honor of Brazilian paleontologist Vicentino Prestes de Almeida. The Chiniquá site is now part of the geopark of Paleorrota.
Von Huene (1938) recognized two specimens of Prestosuchus chiniquensis from the Chiniquá area. One specimen was a partial skeleton including a jaw and snout fragments, and its bones were labelled SNSB-BSPG AS XXV 1-3, 5-11, 28-41, and 49. In 1972, this specimen was designated as the lectotype of Prestosuchus chiniquensis. The other specimen, SNSB-BSPG AS XXV 7, consists of the upper part of the hip and sacrum. It was designated as the paralectotype of the species. The lectotype and paralectotype are stored at the Bavarian State Collection for Palaeontology and Geology (Bayerische Staatsammlung für Paläontologie und Geologie, BSPG) institute of the Bavarian Natural History Collections (Staatliche Naturwissenschaftliche Sammlungen Bayerns, or SNSB) in Munich, Germany. Both have been redescribed by Desojo et al. (2020). Huene named several more Prestosuchus-like reptiles shortly afterwards, although he did not consider them to be the same species as Prestosuchus chiniquensis. One specimen, with its fossils labelled as SNSB-BSPG AS XXV 131-139, received its own genus and species: Procerosuchus celer. Another specimen, with its fossils labelled SNSB-BSPG AS XXV 13–24, 26–27, and 44–48, was designated as a second species of Prestosuchus, Prestosuchus loricatus. Some authors have considered Procerosuchus celer or Prestosuchus loricatus to be junior synonyms of Prestosuchus chiniquensis. Others have gone as far as to consider not only Procerosuchus celer a separate genus, but also "Prestosuchus" loricatus. Desojo & Rauhut (2024) established the new genus Schultzsuchus for "Prestosuchus" loricatus, as their analyses disputed a close relationship to Prestosuchus chiniquensis.
Porto Alegre specimens
Four Prestosuchus specimens are stored at the Universidade Federal do Rio Grande do Sul (UFRGS) in Porto Alegre. The first to be described was UFRGS-PV-0156-T, a massive and well-preserved skull discovered along with most of a vertebral column at the Pascual Sanga outcrop in Candelária. It was originally described by Barberena (1978) and has experienced much discussion as to its relations to the original Munich specimens. A more complete partial skeleton from Vale Verde, UFRGS-PV-0152-T, was studied by Nesbitt (2011) along with the Munich lectotype and UFRGS-PV-0156-T. It is anatomically similar to the latter specimen. The most complete UFRGS specimen is UFRGS-PV-0629-T, a partial skeleton from Dona Francisca which was originally described in a thesis by Mastrantonio (2010). This specimen has been the subject of braincase (2013), skull (2019), and postcranial (2024) descriptions, as well as hip muscle reconstructions. The least complete UFRGS specimen is UFRGS-PV-0473-T, an isolated braincase which may be from the "Posto de Gasolina" outcrop in Dona Francisca. Porto Alegre has one additional Prestosuchus specimen unaffiliated with the UFRGS: MCP-146, a portion of the hip area stored at the Museu de Ciências e Tecnologia of Pontífícia Universidade do Rio Grande do Sul.
Other specimens
Various other museums have their own Prestosuchus specimens. One of the most spectacular specimens, ULBRA-PVT-281, consists of a very large and complete skull and partial skeleton discovered at "Posto de Gasolina" and now stored at the Universidade Luterana do Brasil (ULBRA) in Canoas. This specimen was discovered in 2010 and was fully described by Roberto-Da-Silva et al. (2018/2019) The Museu Paleontológico e Arqueológico Walter Ilha in São Pedro do Sul has a selection of Prestosuchus fossils collectively termed CPEZ-239b. CPEZ-239b corresponds to at least two juvenile individuals found at the Baum (Tree) Sanga outcrop, which were described by Lacerda et al. (2016). The only Prestosuchus fossil stored outside of Brazil or Germany is MCZ 4167, an obscure and fragmentary specimen found at "Posto de Gasolina" and held at Harvard's Museum of Comparative Zoology in Cambridge, Massachusetts.
Taxonomic controversies
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