The procolophonid amniote Barasaurus besairiei Piveteau 1955 is fully described and restored for the first time with emphasis placed on the postcranial skeleton, which is only poorly known in most of the other taxa of early amniotes. / The study focuses on testing a hypothesis of relationships, namely whether procolophonids are the sister-group of Testudines as proposed by Reisz & Laurin (1991). The description provides a sound basis for a new phylogenetic study of early amniotes. Using 13 taxa and 68 characters, the analysis indicates that synapsids are the sister-group of all other known amniotes, named Sauropsida. The Sauropsida are divided into Palaeosauropsida and Eusauropsida. Palaeosauropsida comprise Millerettidae as the sister-group of Procolophoniformes. The Procolophoniformes contain Procolophonia and Testudinomorpha as sister-groups. Testudines are the sister-group of Pareiasauria within the Testudinomorpha. Within Procolophonia, the family Owenettidae, including Barasaurus and Owenetta, is the sister-group of the family Procolophonidae. Eusauropsida include captorhinids, Palaeothyris and diapsids. / All of the three major amniote clades have extant taxa: Synapsida--mammals; Palaeosauropsida--turtles; Eusauropsida--diapsids including birds. The terms "Reptilia" and "Parareptilia" are omitted from systematics: Parareptilia for a misleading name and Reptilia in general because of its historical burden. / The new tree is strong in supporting Procolophonia and Testudinomorpha (sister-group of Pareiasauria and Testudines). It is not very firm in establishing eusauropsids and diadectomorphs because they were outside the main focus of the analysis. Mesosauria is the only group of Palaeozoic amniotes not included in this study.

No description available.