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Eohyosaurus, new rhynchosaur from Middle Triassic of South Africa



Ben Creisler
bcreisler@gmail.com


A new paper:

Richard J. Butler, Martín D. Ezcurra, Felipe C. Montefeltro, Adun
Samathi and Gabriela Sobral (2015)
A new species of basal rhynchosaur (Diapsida: Archosauromorpha) from
the early Middle Triassic of South Africa, and the early evolution of
Rhynchosauria.
Zoological Journal of the Linnean Society 174(3): 571–588
DOI: 10.1111/zoj.12246
http://onlinelibrary.wiley.com/doi/10.1111/zoj.12246/abstract

Preprint pdf:
http://pure-oai.bham.ac.uk/ws/files/18665482/Butler_et_al._postprint.pdf


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 gen. et sp. nov., 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 stratigraphical
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 palaeogeographical distribution for early rhynchosaurs,
followed by a global dispersal of rhynchosaurids during the Middle
Triassic.