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Pachyrhinosaurus perotorum braincase



From: Ben Creisler
bcreisler@gmail.com

A new online paper:

Ronald S. Tykoski and Anthony R. Fiorillo (2013)
Beauty or brains? The braincase of Pachyrhinosaurus perotorum and its
utility for species-level distinction in the centrosaurine ceratopsid
Pachyrhinosaurus.
Earth and Environmental Science Transactions of the Royal Society of
Edinburgh (advance online publication)
DOI: http://dx.doi.org/10.1017/S1755691013000297
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9016351&fulltextType=RA&fileId=S1755691013000297



The centrosaurine ceratopsid taxon Pachyrhinosaurus is the most
speciose of centrosaurines, being represented by at least three
species (P. canadensis, P. lakustai, and the recently described P.
perotorum) from the late Campanian and early Maastrichtian of North
America. The species are readily distinguished from one another by
details of easily visible cranio-facial and frill ornamentation,
features commonly used to differentiate ceratopsid taxa. Braincase
material is also known for all three taxa. We describe the braincase
of P. perotorum based on specimens from the Kikak–Tegoseak Quarry of
the North Slope of Alaska. We then compare it to braincase and
endocranial descriptions of the other Pachyrhinosaurus taxa to test
whether there may be useful species-level differences present in these
robust parts of the ceratopsid skull. Braincase morphology, including
cranial nerve paths through the braincase walls in P. lakustai and P.
perotorum, were found to be very similar. Two potential diagnostic
differences between taxa were found, although tests based on larger
sample sizes will be necessary to verify them. This reinforces the
importance of highly visual cranio-facial and frill ornamentation as
the best tool for species recognition and phylogenetic reconstruction
in ceratopsid dinosaurs.