Pachycephalosaurus wyomingensis was the largest of the pachycephalosaurids—"thick-headed dinosaurs"—which featured extremely thick skullcaps. The top of a Pachycephalosaurus skull could be 9 ...

It was easy for them to believe that the bones, a very thick skull about the size of a modern human's and a large, apelike jaw, were part of the same individual because that physiology was what ...