Researchers discover thousands of dinosaur footprints in Alaska

As It Happens6:36Researchers discover thousands of dinosaur footprints in Alaska

Dustin Stewart has been obsessed with dinosaurs since he was nine years old. But he never dreamed he'd grow up to study 70-million-year-old footprints in Alaska.

Scientists have found dinosaur tracks in the Denali National Park before, but never anything on this scale.

Stewart, a paleontologist and graduate from the University of Alaska Fairbanks (UAF), says there are thousands of newly found prints crawling up vertical walls "like Spider-Man." 

"Seeing that for the first time, oh, we were on the next level. Unbelievable. Everyone was excited," he told As it Happens guest host Paul Hunter. "[They were like] 'Oh, my God, look at that one; look at that one.'" 

Stewart is a lead author of the study that analyzed what researchers say is the largest known dinosaur track site in Alaska. He worked alongside Patrick Druckenmiller, the director of the Museum of the North in Fairbanks. The findings were published last month in the journal Historical Biology. 

'We were freaking out'

Stewart and his team set out to learn more after hearing about the site from national park employees, who first noticed some of the tracks in 2015 on a rocky outcrop researchers have since dubbed the Coliseum. 

After hiking for seven or eight hours, he said they weren't very enthusiastic about what they found at first.

"We were exhausted, and we were seeing there [was a] wall that had some dinosaur tracks on it. But not [as many as] we were kind of expecting," he said.

However, when the sun started setting and "hit this perfect angle" on the wall, he says they saw dozens of tracks — and then hundreds, and thousands more.

"Immediately all of us were just flabbergasted, and then Pat said, 'Get your camera.' We were freaking out."

A look back in time

The tracks are believed to trace back about 69 million years, placing them in the Cretaceous period. Stewart says he believes most tracks were from the Pachyrhinosaurus and Nanuqsaurus — the latter a cousin of the Tyrannosaurus rex. 

He says multiple footprints show different types of dinosaurs that were right next to each other, which makes him believe that one dinosaur walked a path one day, and another the next day.

"We're seeing this area of tracks through time and in multiple events that created this kind of environment," said Stewart. 

The researchers believe the Coliseum, which looks like vertical layered rocks pointing outwards, was once horizontal and flat on the ground and near a watering hole.

Many different creatures would gather there for water, he said, which would explain why so many different types of tracks could be found in one spot.

"It is probably similar to something we see in Africa where you see these animals we don't really associate with one another — lions, giraffes, alligators, and they're all there .... in the same area," said Stewart.

The shapes of the footprints ranged from blobs and holes to more defined footprints.

"You can see the shape of the toes and the texture of the skin" in some of the prints, Druckenmiller, senior author of the study, said in a press release.

Possible evidence of dinosaur migration

Donald Henderson, a paleontologist from the Royal Tyrrell Museum of Palaeontology in Alberta who was not involved in the study, says the findings are pretty amazing.

"Normally we just get, you know, maybe, a few metres long and one or two metres wide, but they've got this huge expanse of rock exposed," he said.

Henderson said tracks that lay flat on the ground can be obscured over time. Nearby rocky hills are "constantly being eroded" and can settle onto the ground. Plants can also further obscure tracks as they grow over top them.

However, since the Coliseum "walls" are vertical, nothing can really accumulate, he said.

Last year the museum reported on a dinosaur track site in southern Alberta and found evidence of the same creatures as those Stewart's team found in Alaska.

Henderson said that this discovery shows that animals were living all the way from the far north to the south such as the United States.

During the late Cretaceous period, the planet could be described as a "greenhouse world" with no polar ice caps, Henderson said. Still, dinosaurs living in what is now Alaska probably experienced "long, long dark" polar nights, possibly leading some to migrate.

"That might explain why you've got basically the same dinosaur as in Alberta and Alaska," he said.

Stewart is optimistic there are even more tracks to be found at Denali National Park in the future.

"We're going to find more of [them] every single year we go out there," he said.