Theropods are among the most well-studied groups of non-avian dinosaurs, known for their ancestral carnivory, hollow bones, and three-toed limbs. They are the largest bipedal animals to have ever existed. Several theropod lineages independently achieved gigantic body sizes at different times in geologic history. They include the tyrannosauroids, megalosauroids, and allosauroids. In this thesis, I quantify the effects of large body size on theropod dinosaur feeding biomechanics by analysing 3D models of theropod dinosaur skulls using the finite element method. First, I create and compare 3D models from computed tomography (CT) scans and surface scans of extant diapsid skulls and perform finite element analysis (FEA) under identical loading parameters to discern how scanning methods influence FE results, as my dinosaur models were generated from a mixture of CT scans and surface scans. It was found that once surface scanned models are solidified, they output stress and strain distributions and model deformations comparable to their CT scanned counterparts, though differing by notable stress and strain magnitudes in some cases. Secondly, I examine tyrannosauroids, as the animals varied greatly in their body size distribution and possess a relatively well-understood fossil record. I use FEA to test whether skull shape becomes more or less resistant to feeding induced forces as taxa body size increases. It was found that large-bodied tyrannosauroids experienced higher absolute stresses compared to small-bodied relatives. Lastly, I examine 3D models of theropod dinosaur skulls across several clades including the Megalosauroidea, Allosauroidea, and Abelisauroidea using FEA. My results indicate that tyrannosauroid skulls were more adept at absorbing high stresses associated with strong bite forces and gigantic body sizes, and the general trend of skull strengthening with large body size is most notable in tyrannosauroids and mostly absent in smaller basal theropod dinosaurs.
Macroevolution and function in giant theropod dinosaurs
Rowe, A. J. (Author). 3 Oct 2023
Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)