Euparkeriidae

Abstract

AbstractEuparkeria 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.