Euparkeria capensis has long been considered an archetype for the ancestral archosaur morphology, and has been placed just outside of crown Archosauria by nearly all cladistic analyses. Six species are currently considered to be putative members of a clade Euparkeriidae, and have been collected from Olenekian- or Anisian-aged deposits in South Africa (Euparkeria capensis – the only definitive member of the group), China (Halazhaisuchus qiaoensis, Wangisuchus tzeyii, ‘Turfanosuchus’ shageduensis), Russia (Dorosuchus neoetus) and Poland (Osmolskina czatkowicensis). Four other species (Turfanosuchus dabanensis, Xilousuchus sapingensis, Platyognathus hsui, Dongusia colorata) were historically assigned to Euparkeriidae, but have been removed by recent work. Recent authors deemed Osmolskina czatkowicensis and Dorosuchus neoetus to be the most likely taxa to form a euparkeriid clade with Euparkeria capensis, but Osmolskina czatkowicensis and Euparkeria capensis were not found as sister taxa by the only cladistic analysis to have tested euparkeriid monophyly. Euparkeria capensis was small (<1 m), insectivorous or carnivorous, probably had vision adapted to low-light conditions and a semi-erect crocodile-like stance, and may have been facultatively bipedal. Bone histology demonstrates that Euparkeria capensis had a slow growth rate, which has been suggested to have been an adaptation to relatively stable environmental conditions.
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Archosaurs, an important reptile group that includes today’s crocodiles and birds, arose during the Triassic in the aftermath of the greatest mass extinction of all time. In the last 20 years, our understanding of the early evolution of the group has improved substantially with the discovery of new fossils and species of early archosaurs and their closest relatives, a better understanding of the relationships of these animals, and new insights into their palaeobiology. In order to synthesize these new data, researchers of early archosaurs from around the world met at the first symposium of early archosaur evolution at the IV Congreso Latinoamericano de Paleontología de Vertebrados (September 2011) in San Juan, Argentina. This symposium facilitated collaboration and strove to paint a better understanding of these extraordinary animals. The resultant body of work is a state-of-the-art examination of early archosaur groups and their close relatives including historical, anatomical, biogeographical, evolutionary and palaeobiological data. This contribution furthers our knowledge of the anatomy, relationships, and palaeobiology of species-level taxa as well as more global patterns of archosaur evolution during the Triassic.