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New Species Of Meat-Eating Dinosaur Unveiled In Utah

An artistic rendering of the dinosaur.
Todd Marshall
Allosaurus jimmadseni attack a juvenile sauropod in this artistic rendering.

What has sharp teeth, big, recurved claws, and is almost as long as a school bus?

Allosaurus jimmadseni — the new species of dinosaur unveiled Friday by researchers at the Natural History Museum of Utah. 

The massive carnivore roamed the flood plains of western North America more than 150 million years ago before becoming extinct at the end of the Jurassic Period. Its fossil was originally discovered by a geologist at Dinosaur National Monument in northeastern Utah in 1990, but it took years before scientists realized that it was a different species than its more well-known cousin. 

A picture of a cast of the skeleton and skull of the dinosaur.
Credit Dan Chure
A cast of the skeleton and skull of Allosaurus jimmadseni as it was discovered and now on exhibit at Dinosaur National Monument in Utah. The original skeleton was molded and cast before it was taken apart and prepared for study and research.

“This species of allosaurus actually lived before the more popular Allosaurus fragilis,” Mark Loewen, a research associate at the Natural History Museum of Utah who helped unveil the dinosaur, said. “Really we have an older cousin to that famous fossil.”

This new kind of allosaurus had a weaker and lighter skull than the one we’ve known about since the 1870s, which suggests they hunted different kinds of prey. It’s been named after James Madsen, Utah’s first state paleontologist.

After discovering Allosaurus jimadseni, researchers realized that some well-known allosaurus fossils around the world had been misidentified and actually belonged to this new species, including the famed “Big Al,” which was featured in a BBC documentary and is housed at the Museum of the Rockies in Bozeman, Mont. 

“We recognize special features along the nose, making tiny crests — that was something Allosaurus fragilis doesn’t have,” Loewen said. 

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUER in Salt Lake City, KUNR in Nevada, the O’Connor Center for the Rocky Mountain West in Montana, and KRCC and KUNC in Colorado. Follow Nate Hegyi on Twitter @natehegyi.

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