Dinosaur: Tyrannosaur Family Tree Expands With New Idaho Fossils

Rare fossils unearthed in Idaho have added a few branches to the tyrannosaur family tree. Paleontologists from Montana State University (MSU) say the recent discovery suggests a much more diverse group of theropods roamed the area 95 million years ago than previously thought.

"We don't really have many dinosaurs from this time period," MSU paleontology professor David Varricchio said in a news release. "This new evidence is really filling in the time, temporal and spacial gap."

Dinosaur fossils are a rarity in Idaho. The recent discovery was made at the Wayan Formation, which lies in the Caribou-Targhee National Forest. Based on their findings, researchers believe the fossils represent at least three new small to mid-sized species of theropod -- the family is dominated by carnivorous dinosaurs, including the Tyrannosaurus rex. The larger of the new tyrannosauroids was likely the size of a horse, while the smaller individual was closer to the size of a golden retriever.

Among the researchers' findings was a pair of fossilized eggs belonging to Idaho's largest burrowing dinosaur, the oviraptorosaur. The eggs are actually the first known evidence that oviraptorosaurs lived in what is now Idaho during the middle Cretaceous period.

"The challenge is identifying the animals based on the fragmentary specimens we find," Varricchio added in the university's release. "It's possible I could discover some identifications are wrong if we find more complete remains later."

"It's just disappointing," MSU doctoral student L.J. Krumenacker, lead author of the study, added. "You'd like to find more. But it just drives me to look more. Persistence pays off -- now we've found these other fossil localities giving a lot of more data on the animals present at the time."

The newly identified fossils will be curated at the Idaho Museum of Natural History. Their findings were recently published in the journal Historical Biology.

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