Meeting Abstract
Most carnivorous mammals can pulverize skeletal elements by generating tooth pressures between occluding teeth exceeding cortical bone shear strength, from which access to marrow and phosphatic salts is gained. Conversely, carnivorous reptiles have non-occluding dentitions engendering negligible bone damaged during feeding. As a result, reptilian predators often consume bones in their entirety. Nevertheless, the giant (13 m) theropod dinosaur Tyrannosaurus rex stands out in not only habitually biting deeply into bones, but also pulverizing and digesting them. How this mammal-like capacity was possible in the absence of dental occlusion is not known. To provide the answer we: (1) examined the crania and dentitions of specimens spanning the entire known adult size range for the taxon; (2) characterized the contact areas along the prominent maxillary tooth crowns used to fracture bones during feeding; (3) reconstructed the 3-D muscle architecture, based on Crocodylia and Aves; (4) determined muscle forces, using an experimentally validated, extant archosaurian jaw adductor muscle model; (5) size-scaled muscle forces and quantified the lever mechanics of each jaw to estimate specimen-specific bite-force capacities; (6) deduced pressure generation as the teeth penetrated bones; and (7) considered the failure properties of bone to determine how dental and palatal contact configurations facilitated skeletal element fragmentation. Bone pulverization was made possible through: (1) prodigious bite forces (8,526–34,552 N) and tooth pressures (718–2,974 MPa), promoting crack propagation, (2) dental configurations localizing shear stresses, and (3) repetitive biting. These capacities allowed T. rex to finely fragment bones, unlike any other animal, and to exploit large dinosaur carcasses for sustenance.
