The procolophonoid reptile Sauropareion anoplus from the lowermost Triassic of South Africa

ABSTRACT

The holotype of Sauropareion anoplus, a procolophonoid reptile from the Lystrosaurus Assemblage Zone of the Beaufort Group, lowermost Triassic of South Africa, is described in detail. New information includes the presence of fields of teeth on the vomer, the palatine, and the pterygoid, and the presence of a relatively long, tear-shaped interpterygoid vacuity. The parabasisphenoid features relatively broad posterolateral wings. A cleithrum is present. An entepicondylar foramen is present, but neither an ectepicondylar foramen nor a supinator process are present. We coded Sauropareion for the data matrices in two recent studies that had excluded this genus from consideration in phylogenetic analyses. Running of these slightly augmented matrices results in numerous optimal trees (8 and 15 optimal trees, i.e. the inclusion of Sauropareion greatly weakens the resolution of the tree topologies; in one case the inclusion of Sauropareion highlights the lack of anatomical information available for most procolophonids, and in the other it reveals weaknesses that are possibly attributable to character selection. We conducted a new phylogenetic analysis of Procolophonoidea, incorporating new phylogenetic characters from other studies. Our results confirm the position of S. anoplus as the sister taxon of a clade comprising all procolophonoids exclusive of Coletta seca. New phylogenetic definitions are devised for Owenettidae and Procolophonidae, making the latter one of the two primary clades within Procolophonoidea; Owenettidae and Procolophonidae are now sister taxa. As a result, the non-owenettid procolophonoids species S. anoplus and C. seca can be recognized as the most basal members of Procolophonidae.