Pachycephalosaurus



The anatomy of Pachycephalosaurus is poorly known, as only skull remains have been described.[1] Pachycephalosaurus is famous for having a large, bony dome atop its skull, up to 10 in thick, which safely cushioned its tiny brain. The dome's rear aspect was edged with bony knobs and short bony spikes projected upwards from the snout. The spikes were probably blunt, not sharp.