Supplementary photographs from: The Canadian fossil record supports anagenesis in Triceratops (Ornithischia, Ceratopsia)

Evolution of the ceratopsid dinosaur Triceratops has been hypothesized to have proceeded anagenetically, with the geologically older Triceratops horridus having directly given rise to the younger Triceratops prorsus. This evolutionary scenario is based primarily on the upper Maastricthian fossil record of the Hell Creek Formation in Montana. The Canadian fossil record affords an opportunity to test this hypothesis beyond the geographic bounds where it was originally developed. The Canadian strata (lower Scollard Formation of Alberta and Frenchman Formation of Saskatchewan) are roughly contemporaneous with the upper third of the Hell Creek Formation where T. prorsus is found. On the anagenesis hypothesis, the Canadian strata should, therefore, uniquely contain that species. Our exhaustive survey of the Canadian Triceratops material, supported by cladistic and ordination analyses, confirms the presence of a single species, T. prorsus, in Canada, yielding robust support for the anagenesis hypothesis conceived for the genus.