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Contemporary witness: skeleton of a Thescelosaurus
Photo: CC BY-SA 4.0 / wikimedia commons
A complete leg and skin is one of the spectacular finds proudly presented by paleontologist Robert DePalma.
The fossil of a Thescelosaurus, a bird-footed small herbivore, could be the first to tell directly about the dinosaur extinction.
It was found at the DePalma-led Tanis site, North Dakota, in a layer of sediment attributed to the impact of the asteroid Chicxulub 66 million years ago.
“We have so many details in this place that tell us moment by moment what happened.
It's almost like it's seen on film,' DePalma, a PhD student at the University of Manchester, told the BBC for a documentary with nature filmmaker David Attenborough, due to air on April 15.
"You see the pillar and the fossils there and it takes you back to that day."
First reported in 2019, Tanis traced the tracks of the 12-kilometer-wide asteroid that struck 3,000 kilometers off the Yucatan coast and was believed to end the age of the dinosaurs.
At the time, Tanis, in the middle of the North American prairie, was on the coast of a vast bay and was hit hard by the blast.
Fish with asteroid debris in their gills
In the meantime, the excavation team has presented some peer-reviewed studies on its finds.
These include the remains of prehistoric sturgeon fish whose gills still contain glassy particles from molten rock that could be assigned to the impact in Mexico using chemical and radiometric methods.
The fish were buried in a layer rich in the precious metal iridium right after the pieces of glass reached their bones.
This is considered a sure sign that the animals died from the asteroid impact.
Also recovered from Tanis were a turtle impaled on a wooden stake, the skin of a triceratops, the embryo of a pterosaur in its egg, and possibly a fragment of the asteroid Chicxulub itself.
"It's absolutely insane, absolutely stunningly beautiful," enthused natural historian Phillip Manning, who is supervising DePalma's doctoral thesis in Manchester.
"The temporal resolution we get in this place is beyond our wildest dreams."
The thescelosaur died instantly
In particular, Manning singled out the thescelosaur's leg as "the last drumbeat of the dinosaurs."
According to Paul Barrett of London's Natural History Museum, the first preserved skin of this species of dinosaur was found, which was scaly like monitor lizards and not feathered like comparable carnivores.
Barrett told the BBC that the leg showed no signs of being bitten or diseased.
"Our best explanation is that this animal died more or less immediately."
However, Barrett added that it was plausible, but not yet scientifically proven, that the Thescelosaurus actually died on the day the asteroid hit Earth.
It is also conceivable that the already dead animal was lifted out of the ground as a result of the impact and then buried with the rest.
Because the fossil is so well preserved, it must have died at least very shortly before.
Since hardly any dinosaur fossils are found in the upper Cretaceous rock strata, the find would still fill a gap "that has upset paleontologists for decades."
Barrett joined the researcher Steve Brusatte from the University of Edinburgh, who had already shown skepticism about the BBC documentary: The fish with glass splinters are clear evidence of the asteroid.
For the other finds, this still needs to be checked.
“But does it even matter if they died that day or years before?” Either way, the fossils are spectacular.
The pterosaur egg, for example, whose embryo Robert DePalma was able to measure with X-rays and recreate as a 3D model, is unique.
"It doesn't always have to be about the asteroid."
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