While neither group has a bowling ball-like structure on top of its head, the head-slapping behaviour of crocodiles and the face-pecking observed in a variety of birds suggest that 'using your head' is not unique to pachycephalosaurs and domes likely evolved in response to such behaviour," he said.
The investigations reveal that "larger domed pachycephalosaurs such as Pachycephalosaurus may have been head-butting like Dall sheep or head-shoving like bison, while smaller, high-domed taxa such as Stegoceras may have been flank-butting like mountain goats," Peterson said.
The researchers suggest that pachycephalosaurs might have gently nudged heads in a kind of love tap.
Among other things, say the researchers, from the University of California at Berkeley and the Milwaukee Public Museum, the skull of a pachycephalosaur lacks something that bighorn sheep have: air-filled chambers to help cushion a blow.
BONE HEAD Pachycephalosaurs, in Greek, means thick-headed lizards.
A variety of evidence undermines the notion of head-butting pachycephalosaurs, says Goodwin.
Finding out brings us closer to their social lives: were pachycephalosaurs more likely just showing off their domes like peacocks with their tails, or were they also cracking their heads together like musk oxen?
The researchers surveyed the heads of a large number of modern animals as well as one of the world's best dinosaur fossils, the pachycephalosaur Stegoceras validum specimen.
Recent studies have revealed extreme changes in the skulls of pachycephalosaurs
, tyrannosaurs and other dinosaurs that died out about 65 million years ago in North America.