A Subadult Specimen of Rubeosaurus ovatus (Dinosauria: Ceratopsidae), with Observations on Other Ceratopsids from the Two Medicine Formation

作者：McDonald Andrew T^*

来源：PLos One, 2011, 6(8): e22710.

DOI：10.1371/journal.pone.0022710

Background: Centrosaurine ceratopsids are well known from the middle Campanian Upper Two Medicine Formation of Montana. Four taxa have been named: Brachyceratops montanensis, Rubeosaurus ovatus, Einiosaurus procurvicornis, and Achelousaurus horneri. Rubeosaurus has been historically the most enigmatic of these taxa; only two specimens, the holotype caudal parietal bar and a referred incomplete skull, have been assigned to Rubeosaurus.
Methodology/Principal Findings: A revised interpretation of the parietal processes of USNM 14765, the partial skeleton of a subadult centrosaurine formerly referred to Brachyceratops, indicates that it shares a P5 spike with the holotype of Rubeosaurus ovatus and should therefore be referred to that taxon. Brachyceratops is considered a nomen dubium.
Conclusions/Significance: USNM 14765 provides additional anatomical information for Rubeosaurus ovatus. These new data are incorporated into a recent phylogenetic analysis of centrosaurine relationships; Rubeosaurus appears as the sister taxon of a clade composed of Einiosaurus, Achelousaurus, and Pachyrhinosaurus.

• 出版日期2011-8-10