An immaculately preserved dinosaur leg uncovered in North Dakota may be a relic from the day a massive asteroid slammed into Earth, bringing the age of the nonavian dinosaurs to an end, scientists claim. That said, not all experts are convinced that the dino actually died on that fateful day 66 million years ago — or at least, they’re witholding judgment until more data is available for review.
“We need the whole story,” Kirk Johnson, the Sant Director of the Smithsonian National Museum of Natural History in Washington, D.C., told Live Science.
A team led by Robert DePalma, a doctoral student at the University of Manchester in the United Kingdom, uncovered the fossilized leg, which still has skin attached, and suggested that the dinosaur died and became buried during the famous asteroid impact, BBC News reported. The specimen has not yet been described in a peer-reviewed scientific journal.
Johnson said he’s frustrated about the way this discovery and previous ones from DePalma and his colleagues have been presented, with a “big media splash” preceding the release of any detailed, published data. This approach has made many scientists wary of any discoveries made at the fossil site in North Dakota, known as Tanis, he said. “It looks like it’s an amazing site, and the way it’s been rolled out has increased the controversy and doubt about the site,” he said.
According to Paul Barrett, a merit researcher at London’s Natural History Museum, the newfound dinosaur leg belongs to Thescelosaurus, an herbivorous dinosaur whose name means “wonderful lizard” in ancient Greek. “It’s from a group that we didn’t have any previous record of what its skin looked like, and it shows very conclusively that these animals were very scaly like lizards,” Barrett told BBC News. “They weren’t feathered like their meat-eating contemporaries.”
Based on his examination of the fossil, Barrett said the dinosaur’s leg was likely ripped off very quickly, and the limb bears no signs of disease or having been picked apart by scavengers. Barrett examined the fossil on behalf of BBC One, which will soon premiere a documentary(opens in new tab) about Tanis, where the specimen was recovered.
“It’s a cool fossil, if it’s what it looks like,” Johnson said. From the BBC photos and videos, it appears that the dinosaur leg has been mummified. “I don’t think we’ve ever seen a mummy of a Thescelosaurus before,” he told Live Science.
BBC One also called in Steve Brusatte, a vertebrate paleontologist and evolutionary biologist at the University of Edinburgh in Scotland, as an outside consultant on the project. Brusatte told BBC News that he’s skeptical of the idea that the Thescelosaurus perished on the exact day the dino-killing asteroid came whizzing through the sky and punched a huge hole, known as the Chicxulub crater, into the Yucatán Peninsula.
It’s possible that the Thescelosaurus and other animals discovered at the North Dakota site died days or years before but were violently uncovered during the asteroid impact and then reburied along with debris from the planet-rocking event, Brusatte said.
The Tanis site has drawn similar skepticism in the past, Science magazine reported(opens in new tab) in 2019.
That year, Robert DePalma, then a graduate student in paleontology at the University of Kansas, and his colleagues reported finding at the site fossilized fish whose gills were riddled with small glass spheres called spherules. These freshwater fish included sturgeon and paddlefish and were found jumbled together in a 4.2-foot-thick (1.3 meters) deposit, surrounded by scattered remnants of tree trunks and thick mud speckled with more glass spheres, according to Science.