Evolution and ontogeny of feeding in carnivorous archosaurs
My current research centers on feeding adaptations of carnivorous archosaurs, including raptorial birds and large theropod dinosaurs. Theropods have S-shaped necks with the head carried high, good for striking down and forwards. However, Tyrannosaurus rex could also strike and dismember prey with rapid sideways movements of the head (Snively and Russell 2007, Witmer and Ridgely 2009). In my work with John Cotton and Larry Witmer at Ohio University, I am applying multibody dynamics and finite element analysis to model feeding in other archosaurs. We are validating our methods with extant raptors and crocodilians, and emphasizing divergent yet successful morpohlogies among large Cretaceous theropods. Through biomechanical modeling we will test two main hypotheses: The exquisitley preserved abelisaur Majugasaurus crenatissimus, with its bulldog head and derived neck, struck best to the side like a crocodilian or tyrannosaur. In contrast, with its narrow base for muscle attachment yet the largest head among land carnivores, the enormous Giganotosaurus carolinii best struck down and forward like a predatory bird.
These biomechanical studies tie in with larger questions of evolution, ecology, and ontogeny of predation. At the University of Alberta with Philip Currie and Eva Koppelhus, I began large-scale integration of biomechanics, growth, and trophic behavior in theropods and ancient predatory fish. Student colleagues Lara Shychoski, Michael Burns, Robin Sissons, and I are correlating feeding and locomotor adaptations in tyrannosaurids with their predatory hegemony in late Cretaceous Laurasia (Holtz 2009).
Along with simulated biomechanics, I conduct field research on both living and extinct theropods. With the Calgary Wildlife Rehabilitation Society and Cleveland Museum of Natural History, I have fed and filmed many species of raptors to understand their feeding kinematics. My paleontological fieldwork centers on the Oldman Formation of southern Alberta. Tetsuto Miyashita and Darrin Molinaro co-lead our crew, this season excavating remnants of the tyrannosaur Daspletosaurus. Prospecting and excavation are under permit for Francois Therrien (Royal Tyrrell Museum of Palaeontology). This fieldwork is in close coordination with the Southern Alberta Dinosaur Research Group, led by Michael Ryan (Cleveland Museum) and David Evans (University of Toronto).