Cranial mechanics and feeding in Tyrannosaurus rex

Emily J. Rayfield

Abstract

It has been suggested that the large theropod dinosaur Tyrannosaurus rex was capable of producing extremely powerful bite forces and resisting multi–directional loading generated during feeding. Contrary to this suggestion is the observation that the cranium is composed of often loosely articulated facial bones, although these bones may have performed a shock–absorption role. The structural analysis technique finite element analysis (FEA) is employed here to investigate the functional morphology and cranial mechanics of the T. rex skull. In particular, I test whether the skull is optimized for the resistance of large bi–directional feeding loads, whether mobile joints are adapted for the localized resistance of feeding–induced stress and strain, and whether mobile joints act to weaken or strengthen the skull overall. The results demonstrate that the cranium is equally adapted to resist biting or tearing forces and therefore the‘puncture–pul’ feeding hypothesis is well supported. Finite–element–generated stress–strain patterns are consistent with T. rex cranial morphology: the maxilla–jugal suture provides a tensile shock–absorbing function that reduces localized tension yet ‘weakens’ the skull overall. Furthermore, peak compressive and shear stresses localize in the nasals rather than the fronto–parietal region as seen in Allosaurus, offering a reason why robusticity is commonplace in tyrannosaurid nasals.