Scientists unearth a fossil of a dinosaur killed in an asteroid impact

Archeologists have uncovered a brilliantly preserved fossil of a Thescelosaurus leg, complete with skin, at the Tanis dig site in North Dakota, United States.

This leg is just one of a slew of extraordinary discoveries emerging from the famous excavation site, and it's not only the pristine condition of the fossil that's causing such a stir. It's what these ancient fossils are thought to represent, according to scientists.

The scientists believe that the fossils discovered in Tanis were killed and entombed on the day a massive asteroid known as Chicxulub slammed into Earth 66 million years ago, marking the end of the dinosaurs reign and the advent of mammals.

Killed on the day Chicxulub hit Earth

It's now widely accepted that a 7-mile rock struck the Earth 66 million years ago, causing massive earthquakes and volcanic eruptions thousands of miles away. This impact caused the last mass extinction, resulting in the loss of three-quarters of all plants and animals on Earth, including all dinosaurs, with the exception of those species that were ancestors of today's birds.

Scientists have identified the impact site to be in the Gulf of Mexico, off the Yucatan Peninsula. That's roughly 1,860 miles away from Tanis, where the fossil of the new Thescelosaurus leg was found. The event emitted such enormous energy that its devastation was felt for miles.

Thanks to the discovery in the North Dakota fossil site which housed the fossil leg in a chaotic tangle of remains of animals and plants for thousands of years, scientists believe they have been given an unprecedented perspective into the last day of the dinosaurs.

The perfectly preserved leg of a dinosaur

The latest discovery was made by University of Manchester paleontologist Robert DePalma. The leg of a Thescelosaurus, a small herbivore, was likely ripped off after the asteroid impacted and triggered a flash flood.

Due to the presence of debris from the hit, which showered down only in its early aftermath, the fully preserved leg can be precisely dated to the time the asteroid wiped off the dinosaurs, which is why scientists believe that this is the first dinosaur victim from the famous asteroid strike that has ever been discovered.

As reported by the BBC, the crew also discovered the fossilized remains of a turtle skewered by a wooden stick, small mammals and their burrows, triceratops skin, a pterosaur embryo inside its egg, and what scientists believe to be a fragment from the asteroid impactor itself. 

"This is the most incredible thing that we could possibly imagine here, the best case scenario… the one thing that we always wanted to find in this site, and here we've got it," DePalma told the BBC. "Here we've got a creature that was buried on the day of impact – we didn't know at that point yet if it had died during the impact but now it looks like it probably did."

The BBC reported on the findings after being allowed exclusive access to the site for the documentary with Sir David Attenborough. The documentary, titled "Dinosaurs: The Final Day with David Attenborough," will show on BBC One on Friday, April 15, providing the audience a first look at additional significant discoveries.