Teen dinos' violent head-butting battles revealed

Washington, April 1 : Ongoing research into the head-butting behaviour of pachycephalosaurs-a group of relatively small dinosaurs that lived from about 80 million to 65 million years ago in Asia and North America-suggests that they the thick-headed reptiles might have passed through a combative teenage stage in which they butted heads in violent clashes.

Eric Snively of the University of Alberta and Andrew Cox of Villanova University say that the skulls of younger pachycephalosaurs would have been equipped with radiating structures that compressed when rammed, and such structures would have cushioned the blow during head-to-head combat.

For the study detailed in the journal Palaeontologia Electronica, the researchers developed computer models of the skulls of a Homalocephale colathoceros, a Pachycephalosaurus wyomingensis and a Pachycephalosaurine sub-adult, basing their models on photographs and reconstructions of the skulls.

The researchers say that their aim was to determine on the amount of force invested during the smash-ups, how that stress was distributed along the skulls, and ultimately the post-ramming state of the skulls.

"The highest forces we got for a large pachycephalosaur were about 14,000 Newtons, or about as much as T. rex would exert with one of its back teeth," Live Science quoted Snively as saying.

The researcher also suggested that the skull of Homalocephale would have handled most scenarios, though during high-speed impacts, its skull could not fully dissipate the stress in the region in front of the brain.

"The stresses in big adults were usually far below those that would break the bone," Snively said.

He, however, noted that research by Mark Goodwin of the University of California-Berkeley's Museum of Paleontology and Jack Horner of Montana State University's Museum of the Rockies had shown that an adult pachycephalosaur would not had almost no blood vessels embedded in its dome.

"We don't know how it could heal internally. Any sort of damage would be bad news," Snively added.

The researcher further said that the sub-adult skull was much more resilient.

"When they were older teenagers or young adults, that's when they would be best at head-butting," Snively said.

The researcher, however, cautions that just because the thick-headed reptiles could ram heads does not mean they did so.

Currently, Snively and colleagues are examining the skulls of pachycephalosaurs for any evidence of head-butting injuries.

ANI