Co-PIs: Andrew A. Farke, Catherine A. Forster, and Mark A. Loewen
The Late Cretaceous was a period of elevated sea levels and hothouse climates. Shallow seas flooded many continental landmasses, including North America. For about 35 million years, the Late Cretaceous Interior Seaway extended from the Arctic Ocean to the Gulf of Mexico, effectively dividing the North American continent into two landmasses. On the western landmass, sandwiched between the seaway to the east and rising mountains to the west, dinosaurs underwent dramatic diversification, achieving perhaps the acme of their evolutionary history. One of the most successful groups of these ?West American? dinosaurs was the ceratopsids, giant (4-8 m long; ~1-4 ton), rhinoceros-like horned dinosaurs that included Triceratops. Ceratopsids rank amongst the most remarkable animals known. The largest examples possessed skulls about 3 m long, exceeding that of all other land-dwelling vertebrates (back-boned animals) before or since. Their skulls were not only big, but bizarre, with toothless beaks, greatly enlarged nose regions, and a broad array of signature ornaments that included horns over the nose and eyes, together with a variety of elaborate hooks, spikes, and scallops along the frill margin. This project will investigate the evolutionary radiation of ceratopsid dinosaurs, building on abundant recent discoveries that, over the past five years alone, have more than doubled the number of recognized species. The approach will be multi-pronged, assessing and integrating five key components: 1) taxonomy?evaluating and classifying species diversity; 2) phylogeny?assessing the historical relationships of species; 3) stratigraphy?determining how species were arrayed through time; 4) biogeography?evaluating how species were arrayed through space within the Western Interior; and 5) paleoenvironment?looking for associations between species and ancient environments. A cornerstone of the project will be the first comprehensive, species level assessment of historical relationships within Ceratopsidae, predicated on a thorough taxonomic reassessment of the group. The results of this analysis will then be integrated with stratigraphic, paleoenvironmental, and biogeographic datasets in order to test a pair of general hypotheses pertaining to the mode and tempo of evolution. The first hypothesis is that, for most of their duration, ceratopsids were sub-divided into at least two semi-isolated geographic regions?one in the north (including Alberta, Montana, and Alaska) and another in the south (including Utah Colorado, New Mexico, Texas, and Mexico). That is, on the basis of preliminary evidence, it appears that ceratopsid species evolved relatively independently in the northern and southern regions of the Western Interior. The second hypothesis is that the evolutionary radiation of ceratopsids was characterized by relatively rapid species turnover tied to cyclical rise and fall of the Western Interior Seaway. In short, periodic expansion (transgression) of the seaway reduced the amount of available habitat for ceratopsids and other terrestrial animals, perhaps triggering bouts of extinction and speciation. The significance of this project resides in its great potential to elucidate the tempo and mode of evolution within a single, well sampled group of dinosaurs that diversified on a small landmass over a relatively brief geologic time span (~15 million years). Ultimately, the results will comprise the most comprehensive assessment to date of evolutionary radiation within any dinosaur group. Broader impacts will encompass career training for undergraduate and graduate students, including women and minorities, as well as critical elucidation of dinosaur evolution immediately prior to the K-T boundary. In addition, project results will be disseminated to both the scientific community and the general public through a variety of outlets, including original publication, media exposure, the internet, museum displays, and lectures/seminars. Outreach highlights include the most comprehensive treatment of horned dinosaurs on permanent exhibition anywhere in the world, planned for the new, $100 million Utah Museum of Natural History facility in Salt Lake City.
