The first ever fossilised remains of a dinosaur that was killed on the day a massive asteroid struck Earth 66 million years ago have been unearthed by palaeontologists.
They discovered the leg of a Thescelosaurus – a small herbivore – alongside a fragment of the seven mile-wide space rock that killed it.
Experts believe the limb, complete with skin, was likely ‘ripped off’ when the Chicxulub asteroid hit, and then buried in fallen debris on the day of impact.
Its fossilised leg was unearthed alongside a series of remarkable finds at the Tanis fossil site in the US State of North Dakota, known as the ‘Hell Creek Formation’.
The site, which was first discovered in 2008, is extraordinary because it appears to record the events from the first minutes until a few hours after the impact of the Chicxulub asteroid in extreme detail.
Palaeontologists say this is the first discovery of a dinosaur victim from the famous asteroid strike, which left a 93-mile-wide impact crater in what is today the Gulf of Mexico.
They also think they have uncovered a tiny fragment from the space rock that ended the era of the dinosaurs and led to the rise of mammals.
University of Manchester palaeontologist Robert DePalma, who made the discoveries, said they could provide the first ever physical evidence that dinosaurs were killed by an asteroid strike at the end of the Cretaceous Period.
Very few dinosaur remains have been found in the rocks that record even the several thousand years before the impact, so to discover a fossil from the day of destruction itself would be extraordinary.
A new BBC documentary presented by Sir David Attenborough to be aired next week will reveal several new findings at Tanis.
The fossilised leg (pictured) once belonging to a dinosaur known as Thescelosaurus was likely ripped off in a flood, according to researchers
Spherules (glass beads of Earth rock) rained down from the sky less than an hour after the famous Chicxulub impact event and are now preserved at Tanis
There’s around 1,800 miles between Tanis and the site of the Chicxulub impact crater (on the modern-day Gulf of Mexico, off the Yucatan Peninsula). The shattering force of the impact was felt across the planet, and there were at least two massive waves, which battered the land with about 20 minutes in between
‘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 findings were reported by the BBC after the corporation and Sir David Attenborough were granted exclusive access to the site for the documentary.
Entitled ‘Dinosaurs: The Final Day with David Attenborough’, the documentary will be aired on BBC One on Friday, April 15.
Filmed over the course of three years at Tanis, the documentary will also give the public a first glimpse of other historic findings.
These will include fish that breathed in impact debris, a fossilised turtle that was skewered by a wooden stake and skin from a horned triceratops.
‘We’ve got so many details with this site that tell us what happened moment by moment, it’s almost like watching it play out in the movies,’ DePalma said.
‘You look at the rock column, you look at the fossils there, and it brings you back to that day.’
Researchers will submit their findings for peer-review so they can be confirmed, before being published in journals.
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The findings were reported by the BBC after the corporation and Sir David Attenborough (pictured) were granted exclusive access to the site. Here, Sir Attenborough studies skin from a horned triceratops
Palaeontologist Robert DePalma studies one of the fossils in a lab in North Dakota. Researchers will submit their findings for peer-review so they can be confirmed, before being published in journals
A TIMELINE OF THE HELLS CREEK EVENT
Researchers estimate seismic waves hit the Hell Creek Formation within 10 minutes of the Chicxulub asteroid impact 66 million years ago.
These would have been the equivalent of waves from magnitude 10 or 11 earthquake.
The team suspects an inland sea then spawned at least two massive waves, called seiches.
These battered the land with only about 20 minutes in between, ultimately dropping more than six feet of deposits on top of the doomed creatures at the site.
All the while, deadly glass beads called tektites rained down from the sky like tiny ballistic missiles traveling 200 miles per hour.
The fossil record shows these beads continued to pelt the surface for 10 to 20 minutes after the first wave, before a second hit and buried the stranded fish in sand and gravel.
This thick deposit was eventually sealed off with a layer of iridium-rich clay – a material that’s rare on Earth, but common in asteroids and comets.
Professor Paul Barrett at the Natural History Museum in London said the preserved leg once belonged to a dinosaur in the Thescelosaurus genus, a name that translates as ‘wonderful lizard’.
‘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 the BBC. ‘They weren’t feathered like their meat-eating contemporaries.
‘This looks like an animal whose leg has simply been ripped off really quickly. There’s no evidence on the leg of disease, there are no obvious pathologies, there’s no trace of the leg being scavenged, such as bite marks or bits of it that are missing.
‘So, the best idea that we have is that this is an animal that died more or less instantaneously.’
It’s already well known that the dinosaurs were wiped out by the Chicxulub impact event – a plummeting asteroid or comet that slammed into a shallow sea in what is today the Yucatán peninsula in Mexico around 66 million years ago.
For those not killed directly by the impact, the collision released a huge dust and soot cloud that triggered global climate change, wiping out 75 per cent of all animal and plant species.
All non-avian dinosaurs, pterosaurs, ammonites and most marine reptiles disappeared, whilst mammals, birds, crocodiles and turtles survived.
When the asteroid impacted Earth, it rocked the continental plate and caused huge waves in water bodies, such as rivers and lakes.
These moved enormous volumes of sediment that engulfed fish and buried them alive, while impact spherules (glass beads of Earth rock) rained down from the sky, less than an hour after impact.
Ian Kellett on location in Tanis, North Dakota filming one of the new findings – skin from a horned triceratops – whilst still in the ground
Picture shows palaeontologist Robert DePalma working on a fossil at the Tanis dig site – which formed at the time of impact – in North Dakota US
DePalma told the BBC: ‘We’ve got so many details with this site that tell us what happened moment by moment, it’s almost like watching it play out in the movies’
Tanis was discovered in 2008 but only in a 2019 paper was it announced to the world, along with discoveries including fish embedded with spherules, dinosaur bones, fossils of marine reptiles, feathers, eggs, plant material and more.
There’s around 1,800 miles between Tanis and the site of the Chicxulub impact crater (on the modern-day Gulf of Mexico, off the Yucatan Peninsula), but the force of the impact meant it had ramifications for the whole planet.
DePalma told Smithsonian that seismic waves emanating from the asteroid impact reached Tanis within minutes.
The disturbance created freak waves known as seiches that tossed fish and other organisms around, as if they were in water flowing back and forth in a bathtub.
Around 66 million years ago, freak waves known as seiches caused by the Chicxulub impact tossed fish and other organisms around as if they were in water flowing back and forth in a bathtub (artist’s impression)
‘As far as we can tell, the majority of the articulated carcasses are from animals that were either killed when they were encapsulated by the muddy sediment, or very shortly prior as part of the same violent inundation surge event,’ he said.
Earlier this year, scientists from Sweden announced that the Chicxulub impact event occurred in the northern hemisphere’s spring.
They studied bones of six fish that died less than 60 minutes after the asteroid impacted, recovered from Tanis, to reveal secrets about time of death.
