It’s one of several amazing finds at a unique fossil site in North Dakota’s Hell Creek Formation that preserved remnants of the cataclysmic moment that ended the dinosaur era — a watershed moment in the planet’s history.
The fossils Fish that have been unearthed include fish that have sucked in debris that was thrown out in the process the strike, a turtle impaled with a stick, and a leg that may have belonged to a dinosaur that witnessed the asteroid impact.
DePalma, a postgraduate researcher at the University of Manchester in the UK and Associate Professor of Geosciences at Florida Atlantic University, began work at Tanis, as the fossil site is known, in 2012.
The dusty, exposed plains are in stark contrast With what the site would have looked like at the end of the Cretaceous period. Then the American Midwest was a swampy rainforest, and a now-vanished inland sea — known as the Western Interior Seaway — ran from what is now the Gulf of Mexico to Canada.
Tanis is more than 2,000 miles from the Chicxulub impact crater left by the asteroid that slammed off the coast of Mexico, but initial discoveries made at the site convinced DePalma it provides rare evidence of what ended of the dinosaur era.
The site is home to thousands of well-preserved fish fossils that DePalma believed were buried alive by sediment shifted when a massive body of water released by the asteroid impact made its way up the inner seaway. Unlike tsunamis, which can take hours to reach land after an earthquake occurs at sea, these moving bodies of water, known as seiches, shot into the sea immediately after the massive asteroid struck.
“One piece of evidence began to pile up and change history. It was a sherlock-holmes-like sequence of leads,” DePalma said.
“It tells moment-to-moment what happens right after impact, and you end up with such a rich resource for scientific investigation.”
Many of the latest discoveries revealed in the documentary have not been published in scientific journals.
Michael Benton, a professor of vertebrate palaeontology at the University of Bristol who served as the documentary’s science adviser, said although it was a “matter of convention” that new scientific claims should be peer-reviewed before being revealed on television , he said, and many other paleontologists accepted that the fossil site truly represents the “last day” of dinosaurs.
“Some experts have said, ‘Well, it could be the day after or a month before that… but I prefer the simplest explanation, which is that it really documents the day the asteroid hit Mexico,’ he said via email .
“In this amber we found a series of globules that were basically frozen in time because just like an insect in amber that is perfectly preserved, when these globules entered the amber, water couldn’t get to them. They never turned to clay and they are perfectly preserved,” he said.
It’s “like getting a sample vial, going back in time and getting a sample from the impact site, and then keeping it for science,” DePalma said called.
They were able to locate some small unmelted rocks in the glass beads. Most of these tiny rock fragments were calcium-rich — likely from the limestone beneath the Yucatan Peninsula, DePalma said.
“But two of these were completely different in composition. They had peaks in chromium and nickel and some other elements found only in meteoritic material, and these fragments, based on our preliminary analysis…are almost certainly of cosmic origin.”
“This example of a potentially tiny fragment, maybe micrograms, of the colliding asteroid — the fact that a record of that survives would be mind-blowing,” said Goddard chief scientist Jim Garvin, who has studied impact craters on Earth and Mars.
Research on the amber burials spherules has not been published in a peer-reviewed journal. During peer review, scientists provide rigorous feedback on each other’s work to ensure it stands up to scrutiny. DePalma said a peer review Paper on the preliminary results will be published “in the coming months”.
An exceptionally well-preserved dinosaur leg with intact skin is another discovery from the Tanis site, featured in the documentary, which first aired in the UK in April and caused quite a stir in the paleontological world.
Very few Cretaceous fossils have been found in the uppermost rocks of the geological record, and it is possible that the Ast — belonging to a Thescelosaurus, a small herbivorous dinosaur discovered by DePalma and his colleagues — may have died on the very day of the asteroid impact. The preservation of soft tissue such as skin suggests that his body did not have time to decay before being buried in sediment.
“The only two supported scenarios here are that it died in the flood, or it died right before (the asteroid impact) but so close to time that it really didn’t have time to decay. This isn’t something that died years ago and then been reworked. That doesn’t happen with such soft tissues.”
A detailed analysis of the dinosaur’s leg bones could shed light on what the conditions were like before the impact.
Other cool finds from the site include a fossilized pterodactyl, the first found in North America. It shows that the eggs of the giant flying reptiles were soft like those of many modern-day reptiles. A petrified turtle with a wooden stick through its body is evidence that the creature was impaled during the water surge triggered by the asteroid impact.
The work being done at Tanis not only captures in stunning detail what happened on the day the asteroid struck, but also offers insight into an event that caused a mass extinction, and how that mass extinction subsequently unfolded. DePalma hopes this provides a framework to reflect on the climate crisis today.
“The fossil record gives us insight into the details of a global threat and the response of Earth’s biota to that threat,” DePalma said. “It gives us…a crystal ball that looks back into the past and allows us to apply that to today’s environmental and ecological crisis.”
“This is both surprising and an advantage for us. Because by examining this impact event more closely, we can be better prepared to take care of our world now.”