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Callibrachion and Datheosaurus, basal caseasaurian synapsids from Europe + Dimetrodon petition

Ben Creisler

New non-dino papers:

Frederik Spindler, Jocelyn Falconnet, and Jörg Fröbisch (2015)
Callibrachion and Datheosaurus, two historical and previously mistaken
basal caseasaurian synapsids from Europe.
Acta Palaeontologica Polonica (in press)

This study represents a reinvestigation of two historical fossil
discoveries, Callibrachion gaudryi (Artinskian of France) and
Datheosaurus macrourus (Gzhelian of Poland), that were originally
classified as haptodontine-grade sphenacodontians and have been lately
treated as nomina dubia. Both taxa are here identified as basal
caseasaurs based on their overall proportions as well as dental and
osteological characteristics that differentiate them from any other
major synapsid subclade. As a result of poor preservation, no distinct
autapomorphies can be recognized. However, our detailed investigations
of the virtually complete skeletons in the light of recent progress in
basal synapsid research allow a novel interpretation of their
phylogenetic positions. Datheosaurus might represent an eothyridid or
basal caseid. Callibrachion shares some similarities with the more
derived North American genus Casea. These new observations on
Datheosaurus and Callibrachion provide new insights into the early
diversification of caseasaurs, reflecting an evolutionary stage that
lacks spatulate teeth and broadened phalanges that are typical for
other caseid species. Along with Eocasea, the former ghost lineage to
the late Pennsylvanian origin of Caseasauria is further closed. For
the first time, the presence of basal caseasaurs in Europe is

Dimetrodon name conservation petition with ICZN

Case 3695: Dimetrodon Cope, 1878 (Synapsida, SPHENACODONTIDAE):
proposed conservation by reversal of precedence with Bathygnathus
Leidy, 1853