Pachycephalosaurus used its dome head for head-butting combat

The function of pachycephalosaur domes remains debated among paleontologists. The thick-domed skull was once interpreted as a battering ram for intraspecific combat, but recent biomechanical analyses suggest the brain and spine would suffer excessive impact trauma from head-ramming. Alternative hypotheses propose the dome served intraspecific display, species recognition, or dominance signaling among males (similar to bighorn sheep horn displays rather than actual contact). Bone histology and skeletal evidence suggest some striking may have occurred, but whether direct head-collision was a primary function remains contentious.