London: Scientists have uncovered and named a new species of bone-headed dinosaur, pachycephalosaur, from Alberta, Canada.
They have also found that this new species represents the oldest bone-headed dinosaur in North America, and possibly the world.
Approximately six feet long and weighing about 40 kilograms in life, Acrotholus audeti (Ack-RHO-tho-LUS) was identified from both recently discovered and historically collected fossils.
Acrotholus means "high dome," referring to its dome-shaped skull, which is composed of solid bone over 10 centimeters (two inches) thick. The name Acrotholus audeti also honors Alberta rancher Roy Audet, on whose land the best specimen was discovered in 2008.
Acrotholus walked on two legs and had a greatly thickened, domed skull above its eyes, which was used for display to other members of its species, and may have also been used in head-butting contests. Acrotholus lived about 85 million years ago.
The new dinosaur discovery is based on two skull `caps` from the Milk River Formation of southern Alberta. One of these was collected by the Royal Ontario Museum (ROM) more than 50 years ago. However, a better specimen was found in 2008 by University of Toronto graduate student Caleb Brown during a field expedition organized by Dr. David Evans of the Royal Ontario Museum and University of Toronto, and Ryan.
"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 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," he added.
"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.
The fossils of Acrotholus will be put on public display at the Royal Ontario Museum starting May 7, 2013.
The paper describing the new species was published in the journal Nature Communications.