Eubrachiosaurus, redescribed as valid dicynodont from Triassic of North America

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com


New in PLoS ONE:

Christian F. Kammerer, Jörg Fröbisch, and Kenneth D. Angielczyk (2013)
On the Validity and Phylogenetic Position of Eubrachiosaurus browni, a
Kannemeyeriiform Dicynodont (Anomodontia) from Triassic North America.
PLoS ONE 8(5): e64203.
doi:10.1371/journal.pone.0064203
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0064203


The large dicynodont Eubrachiosaurus browni from the Upper Triassic
Popo Agie Formation of Wyoming is redescribed. Eubrachiosaurus is a
valid taxon that differs from Placerias hesternus, with which it was
previously synonymized, by greater anteroposterior expansion of the
scapula dorsally and a very large, nearly rectangular humeral
ectepicondyle with a broad supinator process. Inclusion of
Eubrachiosaurus in a revised phylogenetic analysis of anomodont
therapsids indicates that it is a stahleckeriid closely related to the
South American genera Ischigualastia and Jachaleria. The recognition
of Eubrachiosaurus as a distinct lineage of North American
dicynodonts, combined with other recent discoveries in the eastern USA
and Europe, alters our perception of Late Triassic dicynodont
diversity in the northern hemisphere. Rather than being isolated
relicts in previously therapsid-dominated regions, Late Triassic
stahleckeriid dicynodonts were continuing to disperse and diversify,
even in areas like western North America that were otherwise
uninhabited by coeval therapsids (i.e., cynodonts).