Bone-Headed Dinosaur Is The Oldest Known Pachycephalosaur In North America

[ Watch the Video: Scientists Name New Species of Dinosaur ]

Lee Rannals for – Your Universe Online

Scientists writing in the journal Nature Communications have identified a new species of dog-sized bone-headed (pachycephalosaur) dinosaur.

The team was able to identify the new dinosaur species using both recently discovered and historically collected fossils. The dinosaur, Acrotholus audeti, represents the oldest bone-headed dinosaur in North America, and possibly the world, dating back 85 million years ago.

Scientists used two skull “caps” from the Milk River Formation of southern Alberta, Canada for the study. One of the skull caps was collected over 50 years ago by the Royal Ontario Museum, and the other was discovered in 2008 by University of Toronto graduate student Caleb Brown during a field expedition.

Acrotholus walked on two legs and had a thickened, dome skull above its eyes, which was used for display to other members of its species. Scientists believe the dinosaur may have used its skull in head-butting contests.

“Acrotholus provides a wealth of new information on the evolution of bone-headed dinosaurs. Although it is one of the earliest known members this group, its thickened skull dome is surprisingly well-developed for its geological age,” said lead author Dr. David Evans, ROM Curator, Vertebrate Palaeontology. “More importantly, the unique fossil record of these animals suggests that we are only beginning to understand the diversity of small-bodied plant-eating dinosaurs.”

Researchers believe the skull domes of pachycephalosaurs may be able to help reveal a few more details about Acrotholus. The skull domes of pachycephalosaurs are resistant to destruction, and are much more common than their relatively delicate skeletons. The scientists say fossil records from pachycephalosaurs provide valuable insights into the diversity of Acrotholus.

“We can predict that many new small dinosaur species like Acrotholus are waiting to be discovered by researchers willing to sort through the many small bones that they pick up in the field,” said co-author Dr. Michael Ryan, curator of vertebrate paleontology at The Cleveland Museum of Natural History. “This discovery also highlights the importance of landowners, like Roy Audet, who grant access to their land and allow scientifically important finds to be made.”

Scientists performed scans and computing modeling with pachycephalosaur skulls in 2011 and found that the domes were used as weapons to fend off rivals.

“Pachycephalosaur domes are weird structures not exactly like anything in modern animals. We wanted to test the controversial idea that the domes were good for head butting,” said Dr. Eric Snively, University of Calgary alumnus and post-doctoral researcher in biomedical engineering at Ohio University, a co-author of the study.

They wrote in the journal PLOS ONE that their analyses allowed them to “get inside their heads” by colliding the skulls virtually. They were able to look at the anatomical and engineering of the skull for the animals, as well as the actual tissue types.