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

2011/08/10 by Andrew T. McDonald · 16 citations
Earth and Planetary Sciences · Agricultural and Biological Sciences · #Paleontology and Evolutionary Biology #Paleontology and Stratigraphy of Fossils #Fossil Insects in Amber #Holotype #Nomen dubium #Taxon #Biology #Sister group #Skull #Anatomy #Zoology #Clade #Phylogenetic tree #Taxonomy (biology) #Paleontology

paper · pdf · doi:10.1371/journal.pone.0022710

published in PLoS ONE 6(8), e22710 (Public Library of Science)

openalex publication_date 2011/08/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

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.

Citations

• On dinosaurian reptiles from the Two Medicine formaton of Montana
• Two new horned dinosaurs from the upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae)
• On the Geologic Time Scale 2008
• I. On the classification of the fossil animals commonly named Dinosauria
• A new centrosaurine ceratopsid from the Oldman Formation of Alberta and its implications for centrosaurine taxonomy and systematics
• A New Centrosaurine from the Late Cretaceous of Alberta, Canada, and the Evolution of Parietal Ornamentation in Horned Dinosaurs
• TNT, a free program for phylogenetic analysis
• A NEW BASAL CENTROSAURINE CERATOPSID FROM THE OLDMAN FORMATION, SOUTHEASTERN ALBERTA
• A revision of the late campanian centrosaurine ceratopsid genusStyracosaurusfrom the Western Interior of North America

Cited by

• The oldest centrosaurine: a new ceratopsid dinosaur (Dinosauria: Ceratopsidae) from the Allison Member of the Menefee Formation (Upper Cretaceous, early Campanian), northwestern New Mexico, USA
• Achelousaurus [wikipedia]

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