title: Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae) from the early late triassic ischigualasto formation of Northwestern Argentina.
abstract: Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedal archosauriforms characterized by an elongated and dorsoventrally low skull. The group is endemic from the Middle-Late Triassic of South America. The most recently erected proterochampsid species is "Chanaresuchus ischigualastensis", based on a single, fairly complete skeleton from the early Late Triassic Ischigualasto Formation of northwestern Argentina. We describe here in detail the non-braincase cranial and postcranial anatomy of this species and revisit its taxonomy and phylogenetic relationships. The phylogenetic analysis recovered 'Chanaresuchus ischigualastensis' as part of a trichotomy together with Gualosuchus reigi and Chanaresuchus bonapartei. Accordingly, "Chanaresuchus ischigualastensis" can be potentially more closely related to Gualosuchus reigi, or even Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, after discussing previously claimed synapomorphies of Chanaresuchus, we could not find unambiguous support for the monophyly of the genus. As a result, we propose here the erection of the new genus Pseudochampsa for 'Chanaresuchus ischigualastensis', which results in the new combination Pseudochampsa ischigualastensis. The information provided here about the anatomy and taxonomy of Pseudochampsa ischiguaslastensis will be useful for future quantitative analyses focused on the biogeography and macroevolutionary history of proterochampsids.
authors.affiliation: CONICET, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina; INGEO, Instituto de Geología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, San Juan, San Juan, Argentina.
authors.forename: M Jimena
authors.initials: MJ
authors.lastname: Trotteyn
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, West Midlands, United Kingdom.
authors.forename: Martín D
authors.initials: MD
authors.lastname: Ezcurra
mesh_terms: D000818:Animals; D001118:Argentina; D050281:Bones of Lower Extremity / Q000033:anatomy & histology / Q000502:physiology; D001133:Bones of Upper Extremity / Q000033:anatomy & histology / Q000502:physiology; D025061:Dinosaurs / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D053476:Extinction, Biological; D005580:Fossils; D059166:Osteology; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology* / Q000502:physiology; D013131:Spine / Q000033:anatomy & histology / Q000502:physiology; D013909:Thorax / Q000033:anatomy & histology / Q000502:physiology