Phylogeny of the Crocodylotarsi, with reference to archosaurian and crurotarsan monophyly

TLDR

The Crocodylotarsi, a clade defined by Benton and Clark (1988) for archosaurs with a crocodile‑normal ankle, are the focus of this study. This study re‑examines the phylogeny of the Crocodylotarsi using the most relevant fossil material from early non‑crocodyliform members. The analysis incorporates relationships among major archosaurian taxa (Ornithodira, Ornithosuchidae, Crocodylotarsi) and proximal outgroups (Proterochampsidae, Euparkeria). The analysis supports the monophyly of Archosauria, Crurotarsi, and Crocodylotarsi, identifies Parasuchia as the most plesiomorphic Crocodylotarsi clade, places Suchia as the crocodylotarsan core excluding phytosaurs, positions Prestosuchidae, Lewisuchus, and Turfanosuchus dabanensis near the base, and introduces new clades Rauisuchiformes (encompassing the last common ancestor of Aetosauria and Crocodylia) and Paracrocodylomorpha (including Poposauridae and Crocodylomorpha).

Abstract

ABSTRACT The Crocodylotarsi are a group erected by Benton and Clark (1988) for archosaurs that share the "crocodile-normal" ankle structure. In this study, the phylogeny of the Crocodylotarsi was re-examined based on study of most relevant fossil material of the early non–crocodyliform members of the clade. Relationships among the major archosaurian taxa (Ornithodira, Ornithosuchidae, and Crocodylotarsi) and their proximal outgroups (Proterochampsidae, Euparkeria) were also considered. The monophyly of the Archosauria, Crurotarsi, and Crocodylotarsi is supported by the current analysis. The Parasuchia are the most plesiomorphic clade within the Crocodylotarsi. The Suchia comprise the crocodylotarsans excluding the phytosaurs. The taxon Prestosuchidae is placed near the base of this clade, as are Lewisuchus and Turfanosuchus dabanensis. The new taxon Rauisuchiformes includes the last common ancestor of Aetosauria and Crocodylia and its descendants. Rauisuchia (new combination) includes Rauisuchidae, Gracilisuchus, and Paracrocodylomorpha. The new taxon Paracrocodylomorpha is erected for the clade comprising Poposauridae and Crocodylomorpha.