Courtesy/Liz White/University of Oregon

Don't Edit

Editor's note: While the bone described below was the first dinosaur fossil officially confirmed in Oregon, another fossil, which predates the more recent find by 50 years, was found in the state in the early 1960s. Read more about the earlier find here.

Don't Edit

Scientists from the University of Oregon have made a rare and extraordinary find: a bone belonging to a terrestrial dinosaur, the first ever such fossil from a land-dwelling prehistoric creature discovered in the state.

The discovery came in 2015 when earth sciences professor Greg Retallack was in central Oregon, leading a field expedition of students looking for fossilized plants near the town of Mitchell at a hot spot for ancient rocks called the Hudspeth Formation.

The group came upon a pile of ammonites, spiral shaped sea creatures that went extinct around the same time as the dinosaurs. Sitting there, on top of the pile, was a bone, Retallack recounted.

"I knew immediately what it was," he said. "The students were a bit mystified, but I was thrilled."

Don't Edit

Kristin Strommer, publicist for the University of Oregon's Museum of Natural and Cultural History, poses with the fossil. Courtesy/University of Oregon

Don't Edit

Retallack's revelation was first revealed in a paper published this month in the Journal of Vertebrate Paleontology.

The fossil, a toe bone, is thought to be roughly 103 million years old, dating back to the Cretaceous period. It belonged to a creature called an ornithopod, a 17-foot long herbivore that weighed up to 1,500 pounds and walked on two legs.

To understand the significance of the find, you have to know what Oregon looked like more than 100 million years ago.

Back then, the Pacific Ocean stretched far inland from the beaches we know today and the coast started at the Blue Mountains in what is now Eastern Oregon. The shoreline was rocky and rugged and everything west of present day Wallowa was under water.

"Oregon landscapes are rich with Cretaceous rocks, but they rarely contain the kinds of dinosaur remains we see elsewhere in the U.S.," Retallack said in a statement. "The rocks here are the right age but are mostly from under the sea where dinosaurs did not live or from swamps where dinosaur bones are seldom preserved."

Don't Edit

Don't Edit

Wikimedia Commons

Don't Edit

What Retallack believes happened to this particular fossil is something known in paleontology circles as "bloat and float." He believes the ornithopod likely died close to the ocean, became engorged with gases as it decomposed and eventually drifted into the sea where it was likely dismembered by a predator.

The remains of the creature then would have settled to the bottom of the ocean and became fossilized right next to the ammonites with which it was found some 100 million years later.

Researchers weren't able to tell much about this ornithopod because, well, it's hard to tell a lot from a toe bone, but the discovery was still quite exciting, said Samantha Hopkins, professor of earth sciences at the Clark Honors College.

"With such a small piece of the ornithopod, it's hard to say much about its ecology," she said in a statement. "However, just finding it in Oregon is exciting, because we rarely see evidence here of the dinosaurs we know must have been nearby."

For Retallack, it's not the most scientifically-significant find he's had in his long career, but proximity counts for a lot.

"It's not earth shattering," he said. "But it's probably the coolest thing I've found and it's nice for Oregon."

Don't Edit

-- Kale Williams

kwilliams@oregonian.com

503-294-4048