Any of various medium-sized herbivorous dinosaurs of the genus Pachycephalosaurus of the late Cretaceous period of North America, having a beaked mouth, rows of bumps on the head, and a domed skull up to ten inches (25.4 cm) thick.
Origin: New Latin Pachycephalosaurus, genus name
Origin: : Greek pakhus, thick
Origin: + Greek kephalē, head; see ghebh-el- in Indo-European roots
Origin: + Greek sauros, lizard