Meet The 'Mitchell Ornithopod': Oregon's 1st Dinosaur Fossil Find
A long time ago, on what was then the western coast of North America, a dinosaur died. As the body decomposed it filled with gas and began to float. Wind and waves carried its body away from the redwoods-like conifer forests that lined the shore and out into the open ocean, where its bones scattered as it slowly sank.
A hundred million years passed. Mountains formed, oceans receded, and one of the dinosaur’s toes was found in a fossil bed in the central Oregon desert near the town of Mitchell. The shale it was found in is full of fossilized mollusks and aquatic reptiles, but, it was thought, no dinosaurs — until now.
In fact, this small toe bone, roughly the size and shape of a fun-sized candy bar, is the first confirmed dinosaur fossil found in the entire state.
3D model of the Mitchell Ornithopod toe bone by Paul Barrett. Rendering by OPB.
The find was published in the Journal of Vertebrate Paleontology last month, and first reported by The Register-Guard.
Gregory Retallack, a paleontologist at the University of Oregon, found the bone entirely by accident. He’d taken his students to the Hudspeth shale formation to look for fossilized ammonites. Ammonites are extinct ancestors of squid, nautilus, and octopus and are known for their spiral shells.
“They’re quite beautiful,” says Retallack, who brings his students to this location every year, “And amazingly, among this heap of ammonites, we found this fossil bone.”
Oregon is known for its extensive fossil beds, so it might seem surprising that no one had found a dinosaur bone before. But 100 million years ago, when this dinosaur lived, most of Oregon was under the ocean. There was a small sliver of land across the eastern part of the state, but it wasn’t the right type of soil for making fossils.
“We have a beautiful record from, oh, 60 million years on,” Retallack says, “But for the older things, it’s not so good. Every part of the world has its own special lens on the past, it seems.”
It’s not Oregon’s first 100-million-year-old fossil — but back then Oregon’s fossil lens was trained on the ocean, not land.
“We have icthyosaurs, which are marine reptiles. But they aren’t dinosaurs, ” says Samantha Hopkins, a paleontologist at the University of Oregon and an author of the study. Dinosaurs are related to modern birds. Swimming icthyosaurs and flying pterosaurs, which have also been found in the Hudspeth Formation, are related to modern reptiles.
Any land-animal that were preserved died somewhere else, and floated out to sea. “In a way, this might be a record of the terrestrial fauna of Idaho, not Oregon,” Hopkins notes.
So what’s a (potentially) Idahoan dinosaur doing in an aquatic fossil bed in the middle of the Oregon desert?
“Well, we have a theory,” says Retallack, “It’s called bloat and float.”
Bloat and float is exactly what it sounds like. Sometimes, when an animal dies near shore, it fills with decomposing gases and floats. In this case, it floated off what was then the continental shelf and landed in just the right place to leave fossils behind.
It’s impossible to tell what species the dinosaur is from the toe alone. They aren’t even sure what the genus is, or the family is. They just know the order: it’s an ornithopod. Ornithopods were plant-eating dinosaurs that had birdlike pelvises and usually walked on two legs, but sometimes walked on four.
That would be sort of like finding a human toe bone, but only being able to tell that it came from a primate. Retallack hoped to narrow it down further, but that proved difficult.
“I had the summer of the foot fetish. I visited museums all the way from Fairbanks, Alaska to Bozeman, Montana, looking at ornithopod feet,” says Retallack. No bone was a good enough match to make an identification, but the ones that best matched the Mitchell Ornithopod belonged to hadrosaurs, or duck-billed dinosaurs.
It’s impossible to tell for sure without more fossils, but it would be fitting if the first dinosaur found in Oregon was a hadrosaur — the first complete dinosaur skeleton ever found was one, too.
“There is one sad thing: Oregon’s first dinosaur isn’t quite a duckbill. The Mitchell Ornithopod lived before duckbills showed up,” notes Retallack, “Sorry, Duck Fans. Too bad. ”
Since they can’t tell what species it is, they don’t get to give it a scientific name. It’s just the “Mitchell Ornithopod.” But Retallack thinks Oregon’s first fossil is worthy of a nickname, at the very least, “I was thinking something like Emily. Or Bob. I kind of like Emily. I don’t know why.”
It’s a little unusual to get this excited about such a small fossil find. But because coastal parts of North America were terrible at forming fossils, this toe bone is one of the only glimpses into the Northwest from that time period we have. It’s not clear where this ornithopod fits into the Northwest’s ancient ecosystems.
“It would be great to know!” Hopkins laughs. “It’s sort of silly. I’m a vertebrate paleontologist, and this is, of all of the things I have published, the scrappiest piece of evidence I have ever used for a publication.”
Because the toe bone is exactly that: just a toe. It can’t tell us the ecology of Oregon, or what the dinosaur ate, or even what sex it was.
It’s the rarity of this find that makes it special. It’s the first dinosaur fossil confirmed in Oregon, so it’s the first indication that anyone has had at what prehistoric life may have looked like near where Oregon is today. We suspected, but couldn’t say definitively, that dinosaurs were in this sliver of North America. Now we can.
“It’s a small data point, but it is a dinosaur! And it was found in the rocks in Oregon,” says Hopkins. That in and of itself is novel.
And if there’s one, there’s probably another. Now that Retallack and Hopkins’ paper has been published, people might know what to look for. And the fossil itself will be on display at the Museum of Natural and Cultural History at the University of Oregon.
One amateur rockhound has already sent a specimen Retallack’s way. It had been sitting in the man’s backyard for years. Retallack won’t say much about it (the research still needs to go through peer review) but maybe Emily (or Bob) will get a new friend.
Listen to OPB's Erin Ross discuss the dinosaur fossil find with "All Things Considered" host Kate Davidson in the audio player below.
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