A reconstruction depicts how Acrotholus audeti may have looked.
Scientists in Canada believe they have just identified the oldest dome-headed dinosaur of its kind.
After three specimens of a small, dog-sized dinosaur turned up near a provincial park in Alberta, Canada, a team of researchers investigated the fossils — only to find out they dated back at least 85 million years. The species, Acrotholus audeti, was an 85-pound, thick-skulled dinosaur. In fact, its skull was more than two inches thick according to a recently published article in the scientific Nature Communications journal.
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The bones were found on a farm belonging to resident Roy Audet, and as a result, the species was partially named after the Canadian. Bone-headed dinosaurs, or thick-headed lizards, are often known as pachycephalosaurs in the scientific community.
David Evans, who led the expedition and is a curator at the Royal Ontario Museum, remarked on his findings to the BBC. “What’s interesting about Acrotholus is that it’s the oldest known pachycephalosaur from North America, and it might be the oldest known pachycephalosaur in the world.”
According to the Huffington Post, the fossils are about 5 million years older than the next known pachycephalosaur specimen found on the continent. Another pachycephalosaur was discovered in Mongolia, but it’s unclear which fossil is older.
So why is this find so remarkable in comparison to discoveries of its large and terrifying brethren? Huffington Post reports:
Given the diversity of small animals in modern times, researchers would expect to see that ancient ecosystems had a large share of tiny dinosaurs. But dinosaurs that weighed less than about 220 lbs. (100 kilograms) don’t fossilize well. Any bones that weren’t immediately scattered or weathered into dust were often washed away from the death site, leading to jumbled, confused fossil sites. Big beasts such as long-necked, bus-sized sauropods are easier to unearth.
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Evans and his colleagues found that pachycephalosaur diversity in the scientific community was significantly underestimated. “What Acrotholus does is it extends our knowledge of the anatomy of this group early in their evolution — and it’s actually important for understanding the evolution of pachycephalosaurs in general.
The fossils of Acrotholus audeti will go on display at the Royal Ontario Museum in Canada later this month.