Acrotholus Audeti

New dinosaurs are discovered all the time, even among bones discovered decades ago. All it takes is another look, as was the case of a skullcap found 50 years ago which turned out to be the remains of the oldest bone-headed dinosaur in North America.

Acrotholus audeti was about six feet long and weighed about 80 pounds (40 kilograms) with a dome-shaped skull over 10 centimeters thick. Alive 85 million years ago, the reptile walked on two legs.

The original skull was found 80 years ago in the Milk River Formation of southern Alberta, but a later excavation for the Southern Alberta Dinosaur Project in 2008 uncovered a better specimen for study.

The two pieces were identified together as a new species by David Evans of the Royal Ontario Museum and Michael Ryan of the Cleveland Museum of Natural History, and it was named for Alberta rancher and landowner Roy Audet, on whose property the new specimen was discovered. The specimens were put on side-by-side display in the Royal Ontario Museum beginning in 2013.