A new species of basal rhynchosaur (Diapsida: Archosauromorpha) from the early Middle Triassic of South Africa, and the early evolution of Rhynchosauria

Rhynchosauria was an important clade of herbivorous archosauromorph reptiles
during the Triassic, with a worldwide distribution. We describe a new genus and
species of early rhynchosaur, Eohyosaurus wolvaardti, from the early Middle Triassic (early Anisian) Cynognathus Assemblage Zone (Subzone B) of the Karoo
Supergroup, South Africa. Eohyosaurus wolvaardti is known from a single skull, and is recovered as the sister taxon of Rhynchosauridae in a new phylogenetic analysis,. Cynognathus Subzone B has previously yielded the stratigraphically oldest well-understood rhynchosaur species, Mesosuchus browni and Howesia browni. Eohyosaurus wolvaardti increases the rhynchosaur diversity within this stratigraphic horizon to three species. Intriguingly, all currently confirmed rhynchosaur occurrences from the Early Triassic to earliest Middle Triassic are from South Africa.
This may suggest a relatively restricted palaeogeographic distribution for early
rhynchosaurs, followed by a global dispersal of rhynchosaurids during the Middle Triassic.