Using systematic traits of teeth to test trophic niche evolution in theropod dinosaurs

2012 REU Project:

Tyrannosaurid dinosaurs were dominant predators reaching extraordinary body sizes, but they definitively only occupied this niche for the last two geological stages (83-65 MYA) of the Mesozoic. It has recently been hypothesized that another theropod clade, the allosauroids, competitively excluded tyrannosauroids from the top predator niches for most of the Jurassic and Cretaceous. The theropod fossil record is relatively poor, however, and support for this hypothesis relies on the temporal and geographic distribution of a handful of body fossils. Theropod teeth are relatively abundant, however, as they were replaced throughout life, and therefore offer a richer source of data with which to test this hypothesis. The museum has collections of theropod teeth from three American Cretaceous formations ranging from >112 to 98 million years ago.

Research methods and techniques: Using the museum’s SEM, an REU intern will analyze microstructural characters of the enamel of select teeth from each formation, along with gross morphological characters for a wider sample, and use these traits to assign the teeth to different theropod clades based on synapomorphies. The size distributions of teeth referable to allosauroids and tyrannosauroids will be compared to determine whether they support the competitive exclusion hypothesis. Statistical approaches to determining minimum numbers of individuals and to account for sampling of juveniles will be applied to determine the robustness of the comparisons between clades.

Curator/Advisor: Dr. Peter Makovicky (Geology)