The monophyly of E uparkeriidae ( R eptilia: A rchosauriformes) and the origins of A rchosauria: a revision of D orosuchus neoetus from the M id‐ T riassic of R ussia

E uparkeria capensis is resolved as the sister taxon to A rchosauria in many cladistic phylogenies and provides a key outgroup which may approximate the ancestral archosaur morphology. Several other taxa have been referred to the family E uparkeriidae, but the monophyly of this taxon remains doubtful and largely untested. To test this monophyly, the archosauriform and putative euparkeriid D orosuchus neoetus from the M id‐ T riassic of R ussia is re‐examined in the light of recent work on the evolution of stem archosaurs. D orosuchus neoetus is found to possess a number of morphological features that place it close to Archosauria, including a sigmoidal femur with a clear attachment region for the m. caudifemoralis musculature, but no unambiguous archosaurian apomorphies. D orosuchus neoetus is included for the first time in a numerical cladistic analysis and is recovered as the sole sister taxon to A rchosauria + P hytosauria. A monophyletic Euparkeriidae including D . neoetus and E . capensis is slightly less parsimonious. In addition, a mandible and pterygoid that were previously referred to D . neoetus subsequent to the original description of the species are also included separately within the phylogenetic analysis and are recovered within Archosauria, possibly raising questions as to their correct taxonomic referral. However, this phylogenetic placement is based primarily on the absence of palatal teeth, but the presence or absence of palatal teeth exhibits considerable homoplasy within A rchosauriformes. Based on other aspects of their morphology, we do not reject the referral of these elements to D . neoetus .