A Historic Find: UO Scientists Discover First Oregon Dinosaur Fossil

Saturday, November 17, 2018

A reconstruction of what the ornithopod, whose fossilized toe bone was discovered by a University of Oregon earth sciences professor, may have looked like during the Cretaceous era more than 100 million years ago. [Courtesy of the University of Oregon Museum of National and Cultural History]

Greg Retallack’s four-decade paleontology career has turned up fossilized plants and ancient soils from North America to Africa and Australia to Antarctica.

But it was a 2015 trip to the tiny town of Mitchell, near Eastern Oregon’s Painted Hills, that turned up perhaps his most interesting find of all: the fossilized toe bone of a dinosaur.

Museums across the country are full of fossilized bones and reconstructed dinosaur skeletons. But the title of a research paper Retallack and other University of Oregon researchers co-authored about the find, published last week in the Journal of Vertebrate Paleontology, highlights its significance: “First dinosaur (Ornithopoda) from early Cretaceous (Albian) of Oregon, U.S.A.”

In other words, no one had found a confirmed fossilized dinosaur bone in Oregon before the discovery by Retallack, a UO earth sciences professor, plant and soil researcher and expert on evolutionary transitions.

It is believed to belong to an ornithopod, a plant-eating dinosaur thought to have lived about 103 million years ago during the Cretaceous Period, the same period in which the Tyrannosaurus rex lived. It is believed to have weighed about a ton and spanned more than 20 feet in length.

“This bone was sitting out there with all the rocks. It was pretty surprising,” Retallack said this week. “No excavation was needed. It was just sitting among the ammonites and coil fossils.”

Just an inch long and less than two inches wide, the earth-toned fossil isn’t much to look at. But Retallack sensed almost instantly that he had found something significant on that summer 2015 dig in Eastern Oregon.

When he found the toe bone, he was on U.S. Bureau of Land Management property below a series of fossil-rich cliffs known as the Hudspeth Formation, an area known for turning up fossils of reptile and dolphin ancestors.

“It was in a marine rock. That is not where you would expect to find dinosaurs,” Retallack said. “We have seen from these same rocks pterosaur bones and a plesiosaur (flying and marine reptiles, respectively). That’s been known for some time. But dinosaurs have been missing until now.”

Still, confirming the discovery required three years of follow-up research and writing by Retallack and fellow UO researchers, including Edward Davis, Paleontological Collection manager at the UO Museum of National and Cultural History; Samantha Hopkins, the museum’s curator of paleontology; and UO doctoral student Paul Barrett, as well as Jessica Theodor, a biological sciences professor at the University of Calgary who was working at the UO on a research sabbatical at the time.

Retallack’s expertise is in plants and soil. So it was his fellow researchers who almost instantly confirmed Retallack’s suspicion when he returned from the dig.

“We looked at it and said, ‘Oh yeah. This is an ornithopod toe bone,’” Hopkins said. “Given the time period when it came from and the morphology, that’s the only thing it could have been.”

Retallack and Davis returned to the site the following spring to more thoroughly document the find, along with a BLM official.

Then Retallack started visiting museums from Montana to Alaska and Canada, examining fossilized dinosaur collections to weigh their characteristics against his find.

“That was really great, I could get a really good idea about what (the bone) was and what it wasn’t,” he said.

Meanwhile, Retallack and the other researchers began writing up the discovery into a research paper for submission to an academic journal. The work was completed in October 2017, and underwent a yearlong peer review process.

Finally, last month, the Journal of Vertebrate Paleontology published the report, declaring that the fossil toe bone was “the first diagnostic nonavian dinosaur fossil from Oregon, a state whose Mesozoic rocks are mostly marine. This discovery is novel evidence of Cretaceous terrestrial environments and faunas in Oregon.”

The discovery has thrown into doubt the long-held thought that dinosaur fossils wouldn’t be found in Oregon, since much of the land that makes up the state today was submerged under water during the Cretaceous era.

“It was a long process,” Davis said. “We hadn’t had a case like this before.” The most likely scenario, he said, is that the ornithopod died on the shore, washed out to sea and burst after filling up with decomposition gasses. The toe bone fossilized over millions of years.

The bone is expected to be placed in the UO Museum of National and Cultural History’s new acquisitions case in the next month, Davis said. And it’s likely to play a role in an upcoming “Explore Oregon” exhibit early next year about, ironically, the lack of dinosaur fossils in Oregon, Davis said.

Retallack said he’s not sure if the discovery will lead to any more dinosaur fossils in Eastern Oregon. But he said he’s already made another discovery that has caught his attention, though he wouldn’t provide any details.

“Things come out of the woodwork when you make a discovery like this,” Retallack said. “That’s what we do, and what’s great about science.”

Source: www.registerguard.com