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

  title={A Subadult Specimen of Rubeosaurus ovatus (Dinosauria: Ceratopsidae), with Observations on Other Ceratopsids from the Two Medicine Formation},
  author={Andrew T McDonald},
  journal={PLoS ONE},
  • A. McDonald
  • Published 10 August 2011
  • Environmental Science, Geography
  • PLoS ONE
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… 
A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the ‘Styracosaurus-line' dinosaurs
Assessed within the stratigraphic, geographical, taphonomic, ontogenetic and phylogenetic framework of Unified Frames of Reference, it is failed to reject the hypothesis that Stellasaurus ancellae represents a transitional taxon within an anagenetic lineage of eucentrosauran centrosaurines.
A subadult individual of Styracosaurus albertensis (Ornithischia: Ceratopsidae) with comments on ontogeny and intraspecific variation in Styracosaurus and Centrosaurus.
An immature individual is described, the smallest known for the species, represented by a complete skull and fragmentary skeleton, and the cranial ontogeny of Styracosaurus is described and compared to Centrosaurus.
A new ceratopsid from the Foremost Formation (middle Campanian) of Alberta
Xenoceratops foremostensis gen. et. sp. nov., a new centrosaurine ceratopsid from the Foremost Formation (Campanian) of Alberta, is described based on frill material from at least three adult-sized
Comparative cranial osteology of subadult eucentrosauran ceratopsid dinosaurs from the Two Medicine Formation, Montana, indicates sequence of ornamentation development and complex supraorbital ontogenetic change
Comparing the only known articulated subadult skulls from the hypothesized eucentrosauran lineage in the Two Medicine Formation enables comparison of early ontogenetic developmental sequence and timing of all three primary cranial ornaments, indicating that parietosquamosal frill and supraorbital ornamentation development may have preceded nasal horncore development in these taxa.
Ontogeny and variation of a protoceratopsid dinosaur Bagaceratops rozhdestvenskyi from the Late Cretaceous of the Gobi Desert
The significance of the intraspecific and ontogenetic variation in the study of the neoceratopsian taxonomy is revealed and implies possible temporary separation between the geological formations of the Gobi Desert yielding distinct protoceratopopsid species.
An Immature Pachyrhinosaurus perotorum (Dinosauria: Ceratopsidae) Nasal Reveals Unexpected Complexity of Craniofacial Ontogeny and Integument in Pachyrhinosaurus
The combination of morphologies in the new specimen suggests either an additional stage of development should be recognized in the ontogeny of the nasal boss of Pachyrhinosaurus, or that the ontagenetic pathway of nasal boss development in P. perotorum was notably different from that of P. lakustai.
Macroevolutionary patterns in cranial and lower jaw shape of ceratopsian dinosaurs (Dinosauria, Ornithischia): phylogeny, morphological integration and evolutionary rates.
The frill is the main driving force in the overall cranial shape within Ceratopsia and evolved secondarily to better co-vary with the lower jaw to produce a more efficient masticatory apparatus.
Ceratopsia increase: history and trends1
The taxonomic history of the Ceratopsia began in 1876 with the description of Monoclonius crassus Cope followed in 1889 by Triceratops horridus Marsh. After a peak of discovery and description in the
Craniofacial ontogeny in Centrosaurus apertus
Bone textural changes were found to be sufficient proxies for relative maturity in individuals that have not reached adult size and frill length is congruent with relative maturity status and makes an acceptable proxy for ontogenetic status, especially in smaller individuals.


Styracosaurus shows intraspecific variation in the shape of the more anteriorly placed P5–P7 ornamentation that are either the typical unmodified crest-shaped epoccipitals of other centrosaurines or are developed as short spikes.
Two new horned dinosaurs from the upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae)
Two new ceratopsid dinosaurs, Einiosaurus procurvicornis and Achelousaurus horneri, are described from the Two Medicine Formation of Montana and suggest an increased rate of evolution that may correlate with the late Campanian transgression of the Bearpaw Sea.
Craniofacial ontogeny in centrosaurine dinosaurs (Ornithischia: Ceratopsidae): taxonomic and behavioral implications
An important implication arising directly from this study is that juvenile and sub-adult centrosaurines are difficult to distinguish taxonomically at the specific level.
The Taphonomy of a Centrosaurus (Ornithischia: Certopsidae) Bone Bed from the Dinosaur Park Formation (Upper Campanian), Alberta, Canada, with Comments on Cranial Ontogeny
Abstract Bone bed 43 is one of at least eight paucispecific Centrosaurus bone beds located in the Dinosaur Park Formation (Upper Campanian) in Dinosaur Provincial Park, Alberta, Canada. It long has
First ceratopsid dinosaur from China and its biogeographical implications
Ceratopsid dinosaurs represent one of the best known dinosaur groups in the Late Cretaceous, and their unquestionable fossil records are exclusively restricted to western North America. Here we
A New Centrosaurine from the Late Cretaceous of Alberta, Canada, and the Evolution of Parietal Ornamentation in Horned Dinosaurs
In 1916, a centrosaurine dinosaur bonebed was excavated within the Campanian-aged deposits of what is now Dinosaur Provincial Park, Alberta, Canada. Specimens from this now-lost quarry, including two
The Ceratopsian Dinosaurs and Associated Lower Vertebrates from the St. Mary River Formation (Maestrichtian) at Scabby Butte, Southern Alberta
Scabby Butte, a limited exposure of late Cretaceous sediments in southern Alberta, Canada, is an important source for the large ceratopsian dinosaur Pachyrhinosaurus Sternberg. New cranial material
A new centrosaurine ceratopsid from the Oldman Formation of Alberta and its implications for centrosaurine taxonomy and systematics
Phylogenetic analysis of the Centrosaurinae suggests that the development of spike-like ornamentation at the parietal locus 3 parietal Locus is inversely related to theDevelopment of the P1 parietal ornamentation.
A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta
In the first monographic treatment of a horned (ceratopsid) dinosaur in almost a century, this monumental volume presents one of the closest looks at the anatomy, relationships, growth and variation, behavior, ecology and other biological aspects of a single dinosaur species.
  • M. Ryan
  • Geology, Biology
    Journal of Paleontology
  • 2007
A limited phylogenetic analysis of the Ceratopsidae places the new taxon as the basal member of the Centrosaurinae and indicates that robust, elongate postorbital horncores that form a synapomorphy of (Ceratops Families + Zuniceratops) are also present in Centrosaurusinae.