Figure 4. Distributions of von Mises stress in a finite element dome model of Pachycephalosaurus wyomingensis. Stress diminishes rapidly away from the point of impact and is very low near the endocranial cavity, in both high- (1) and low- (2) force impacts. Arrows superimposed over a transverse section (3) represent strain direction and relative magnitude through the structure. Strain magnitudes (arrow sizes) diminish markedly deep to the impact, and strain vectors diverge away from the brain.