Scientists at the University of Alaska Fairbanks have discovered and documented the largest known dinosaur footprint area in Alaska. Located in Denali National Park and Preserve, this magnificent site has been named the Colosseum by experts.

The size of a football field and a half, the Colosseum is a magnificent collection of rock layers, each preserving numerous dinosaur footprints. This site provides a comprehensive historical account of the various dinosaur species that evolved about 70 million years ago in what is now known as Inner Alaska. The researchers’ findings and a detailed description of the Colosseum are presented in a paper recently published in the journalism. Historical Biology.

“It’s not just one level of rock with parts,” said Dustin Stewart, the paper’s lead author and a former UAF graduate student who published the article as part of his master’s thesis. “It’s a series in time. There were other famous pieces in Denali before, but nothing of this magnitude.”

At first glance, this place is unremarkable in the context of the park’s expansive landscape: it’s just a multi-layered rock outcrop rising 20 and several floors above its base.

“When our colleagues first visited the site, they saw a dinosaur trail at the base of this massive rock,” said Pat Drakenmiller, senior author of the paper and director of the University of Alaska Northern Museum. “When we first got up there, we didn’t see much either.”

Stewart recalled being stunned at first when he approached the area after a seven-hour hike. Then twilight approached and the crew took another look.

A large footprint of a carnivorous dinosaur, possibly from a Tyrannosaurus rex. The image was created by taking multiple photos from different angles to create a colorfully highlighted three-dimensional view of the course. Image credit: Dustin Stewart

“When the sun hits these beds at a perfect angle, they fly away,” he said. “We were all stunned right away, and then Pat said, ‘Get the camera.’ We were crazy.”

During the Late Cretaceous, the rocks that made up the Colosseum were probably sedimentary deposits on flat ground near a large floodplain. As the Earth’s tectonic plates collided and flexed to form the Alaska Range, the once flat land bent and tilted vertically, revealing rock covered in footprints.

The tracks are a mix of old mud and hardened impressions from tidal tracks, which are formed when sediment fills and solidifies the tracks.

“They are beautiful,” Druckenmiller said. “You can see the shape of the toes and the texture of the skin.”

In addition to the dinosaur tracks, the research team found fossilized plants, pollen grains and evidence of freshwater mollusks and invertebrates.

“All these little clues put together what the environment looks like as a whole,” Stewart said.

A close-up view showing multiple hadrosaurus trace depressions on a wall. The ice pick in the bottom left corner of the frame is about 3 feet long (for scale). Credit: Photo by Patrick Druckenmiller

He said the area is part of a large river system with ponds and lakes nearby. The climate in this area was warmer than it is today, more like a Pacific Northwest climate. There were coniferous and deciduous trees and ferns and horsetail bushes.

Judging by the tracks, various juvenile and adult dinosaurs have visited this area for thousands of years. The most common were large herbivorous platypuses and horned dinosaurs. The team also documented rare carnivores such as raptors and tyrannosaurs, as well as small wading birds.

Druckenmiller said thousands of people visit Denali National Park and Preserve each year to experience the stunning natural scenery and environment. “It’s incredible to know that about 70 million years ago Denali was no less impressive with its flora and fauna.

“It was a jungle and it was full of dinosaurs,” he said. “There was a tyrannosaurus running around Denali, many times the size of the largest grizzly bear in existence today. There were hunters. There were flying reptiles. There were birds. It was an incredible ecosystem.”

Park geologist Danny Capps said preserving fossils like the Colosseum is an important part of the National Park Service’s mission.

“On the one hand, we must protect world-class monuments like the Colosseum from vandalism and theft,” he said. “On the other hand, we encourage visitors to examine the fossils in their geological context to better understand the evolution of landscapes and ecosystems over time, and leave them intact for others to appreciate.”

Drakenmiller plans to continue working with the National Park Service to survey the Colosseum and other sites along the trail. Source