A re-evaluation of Parasaurus geinitzi, the first named pareiasaur (Amniota, Parareptilia)

Abstract

The historically first named pareiasaur Parasaurus geinitzi from the Upper Permian Kupferschiefer deposits of Germany is re-described in detail, including information from recently discovered specimens, as well as material that was for a long time assumed to be lost. The re-study provides new information on both the cranial and the postcranial anatomy of the taxon, the most notable features being the presence of small spikes in the postero-temporal region of the skull and the apparent lack of osteoderms in the axial skeleton, which is unique among pareiasaurs but requires further investigation and new material. A phylogenetic analysis indicates that Parasaurus groups within the more derived pareiasaurs; however, the overall resolution of the analysis is very poor, most likely because many characters traditionally used in studies on pareiasaurian phylogeny were originally defined only for investigating turtle relationships, but not for deciphering the ingroup relationships of pareiasaurs. A careful revision of the phylogeny of the clade is necessary and should also include a detailed assessment of pareiasaurian anatomy, which is still poorly known.