Anatomy, taxonomy and phylogenetic relationships of Prestosuchus chiniquensis (Archosauria: Pseudosuchia) from the original collection of von huene, middle-late triassic of southern Brazil

Abstract

A review of the type and referred material of von Huene shows that Prestosuchus is a valid taxon represented by, at least, three different species: the lectotype and para-lectotype of Prestosuchus chiniquensis, an unnamed species from Brazil (UFRGS-PV-0152-T), and the new combination Prestosuchus nyassicus (=Stagonosuchus nyassi-cus). Several more recently referred specimens are also included within the genus Prestosuchus based on the absence of a vertical crest dorsal to the supracetabular rim; dorsal margin of postacetabular part of ilium concave; marked angle between pubic peduncle/obturator plate and ischial shaft; and elongate posteromedial depression on the distal fibula, making it one of the best known rauisuchian taxa. The phylogenetic analysis recovered a monophyletic Prestosuchidae including Saurosuchus galilei, Luperosuchus fractus, Prestosuchus chiniquensis, Prestosuchus nyassicus, and several specimens referred to the genus Prestosuchus. This clade is supported by the presence of a ridge on the ventral process of the squamosal; anteroventral process of the squamosal perforates the lower temporal fenestra; palpebral bones extensively sutured to each other and to the lateral margin of the frontals; robust, knob-shaped attachment for the musculus iliofibularis on the fibula; and anterior portion of nasals elevated above the skull roof. The identification of this natural group evidenced a remarkable diversity and abundance of basal loricatans in the Middle-Late Triassic continental ecosystems of southern Gondwana.