Why a baby dinosaur bone in the Arctic could change what we know about dinosaur habitats

Artist’s rendering of a juvenile dromaeosaurid 70 million years ago on the Prince Creek Formation in northern Alaska. (Rendering by Andrey Atuchin/SMU)

A new discovery is changing a theory about how dinosaurs once moved about in the Arctic 70 million years ago. A specimen discovered in a lag deposit along the Colville River, about 250 miles north of the Arctic Circle, is evidence that some dinosaurs may have lived on the North Slope year-round. 

Paleontologist Anthony Fiorillo found the specimen at what’s known as Pediomys point, in what’s known as a lag deposit. 

“Any time you do a stream crossing, you would probably walk across a little stretch of the channel that is cobbly,” he explained. “That cobbly part is the lag deposit that is within a river system… and these bones accumulated much the way those cobbles did.”

But all the dinosaur bones he found are not intact, They accumulated there over time, in tiny fragments. Fiorillo said collecting dinosaur specimens here is a lot like mining. “You’re collecting it in a bucket, so you can bring it back to your lab and then do the picking under a microscope,” he said.

Fiorillo is a Research Professor at Southern Methodist University in Dallas, Texas. After he wrapped up his 2007 field season, he brought the material he collected back to his lab. Eventually, he spotted a 14 millimeter bone fragment under his microscope. “It’s got a couple of teeth in it…” he said. But the teeth aren’t what interested Fiorillo most. 

“The bone texture on the outside is very fibrous in nature,” he said. “You can’t really mistake it and that’s what this bone texture is. The size of the teeth and the bone texture itself tell us that this is a very, very young individual,” said Fiorillo.

What he found is a 14 millimeter fragment from the jaw of a baby Dromaeosaur. Fiorillo said the find has upended the theory that dinosaurs that lived in the Arctic must have migrated with the seasons.

“It is a baby,” he said. “It’s not just a juvenile and given the size estimate of this thing, this probably was not far from where the nesting ground was, so this is the first physical proof that at least some dinosaurs nested in the ancient Arctic.”

This new discovery was published this month in the journal PLOS ONE. 

Some of the first Arctic dinosaur remains were discovered back in the 1960’s in Svalbard, Norway. Since then, researchers have theorized that dinosaurs must have migrated to avoid deeply cold winters this far north. But Fiorillo said this new discovery debunks that theory.

“Well, you know the classic stereotype for dinosaurs is that they were living in tropical and subtropical environments.” But, in reality, he said the climate north of Alaska’s Brooks range 70 million years ago was similar to what we might see in Portland or Seattle today. “It was certainly a place where things were capable of being cool at times but certainly warmer than the Arctic today,” said Fiorillo.

The Dromaeosaur is a lot like the velociraptor, made famous in the 1993 film, Jurassic Park. In one scene, two kids are being stalked by two ferocious, hungry velociraptors and the camera zooms in the foot of one of the giant reptiles. It has a hook-like toe. This, said Fiorillo, is what the Dromaeosaur is known for. “They have a specialization in their foot, where their inner toe is lifted off the ground and is a very impressive weapon, which presumably was used in some way in obtaining prey.” 

He said it was surely a formidable predator. 

The jawbone Fiorillo discovered from the Dromaeosaur makes the find the first non-dental specimen associated with the Dromaeosaur that’s been discovered in the Far North. But questions about how dinosaurs lived this far north remain, and that’s where Fiorillo said he planned to take his research next.

“Because even with the warmer temperatures, at the latitude that these dinosaurs were living, which is at least 70 degrees north,” he said, “how did they endure long periods of light and dark?”

Fiorillo said his new discovery proves that these giant reptiles were well-adapted to the highly seasonal environments of the Late Cretaceous, similar to what we still experience today in the Arctic. 

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