Celophisaurus kansansus
Earth History Research Center

The celophisaurs were unique dinosaurs characterized by having extremely thick skulls. The skulls in some of these creatures exceeded 2" in thickness. This bony armor apparently was used in some form of head butting, either in establishing dominance among peers or in defense against enemies, or perhaps both. Behind the skull were a series of bony pointed knobs, also part of the armament.