The Ceratopsia or horned dinosaurs represent an evolutionary radiation of dinosaurs rich in morphological variation but circumscribed taxonomically. The known history of the Ceratopsia extends between late Early Cretaceous and the end of the Cretaceous. Major patterns of the phylogenetic and stratigraphic history of the Ceratopsia have been established. The purpose of the proposed study is to apply procedures of modern multivariate morphometrics, including tensor methods of landmark analysis, finite-element analyses, principal components analyses with appropriate shear, and resistant-fit theta-rho analysis, to samples of Centrosaurus and Chasmosaurus in order to map out patterns of variation within species. A point of focus will be the documentation of fluctuating asymmetries, which may reveal the genetic structure of the species. Functional trends in ceratopsian skulls will be traced, and stratigraphic trends in the evolution of the masticatory system will be determined. I will test the hypothesis that changes in the jaw suspensorium; rejection of this hypothesis will call into question the use of the frill for muscle origins. This study will provide a model for further studies of dinosaur morphometrics, and will contribute to understanding biodiversity of the past, and thus the biodiversity of our own world.
