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

BUTLER, R. J.; EZCURRA, M. D.; MONTEFELTRO, F. C.; SAMANTHI, A.; SOBRAL, G.

ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015

0024-4082

Rhynchosauria was an important clade of herbivorous archosauromorph reptiles during the Triassic, with a worldwidedistribution. We describe a new genus and species of early rhynchosaur, Eohyosaurus wolvaardti gen. etsp. nov., from the early Middle Triassic (early Anisian) Cynognathus Assemblage Zone (Subzone B) of the KarooSupergroup, South Africa. Eohyosaurus wolvaardti is known from a single skull, and is recovered as the sistertaxon of Rhynchosauridae in a new phylogenetic analysis. Cynognathus Subzone B has previously yielded thestratigraphically oldest well-understood rhynchosaur species, Mesosuchus browni and Howesia browni. Eohyosauruswolvaardti increases the rhynchosaur diversity within this stratigraphical horizon to three species. Intriguingly,all currently confirmed rhynchosaur occurrences from the Early Triassic to earliest Middle Triassic are from SouthAfrica. This may suggest a relatively restricted palaeogeographical distribution for early rhynchosaurs, followedby a global dispersal of rhynchosaurids during the Middle Triassic.