How Dinosaurs Died: New Evidence in PBS Documentary

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Thescelosaurus moved stealthily along the shore. Stretching to around 12 feet long and weighing around 500 pounds, the thick-muscled dinosaur was likely foraging for food – or trying to avoid becoming a meal.

Featuring prominent bony eyebrows and a pointed beak, Thescelosaurus trudged on two feet with most of its body bent over forward while a long tail extended backwards for balance. Suddenly, the dinosaur lifted its head and looked around, alarmed as the calm was broken by a series of unnerving natural forces.

The ground began to shake with intense vibrations as the nearby sea water lapped in response. The sky filled with scorching embers, which drifted and set the lush primeval forest ablaze.

Thescelosaurus panicked and sought to flee, but it was too late. Everything changed in the blink of an eye when a 30-foot-high wave of mud and debris swept up the seaway from the south, wiping out life and limbs in the process. The dinosaur was caught in the destructive deluge, its leg ripped off at the hip by the devastating thrust.

That moment – 66 million years ago at the end of the Cretaceous, when an earth-shattering asteroid ended the reign of the dinosaurs – is frozen in time today thanks to a stunning fossil discovered last year at the Tanis dig site in North Dakota. This perfectly preserved paw clearly shows the skin, muscles and bones of the three-toed Thescelosaurus.

Although the details of the death scenario described above are embellished, they are based on remarkable new discoveries and accounts by Robert DePalma, chief paleontologist at Tanis.

“We’re never going to say with 100% certainty that this leg came from an animal that died that day,” the scientist said. “The thing we can do is work out the probability that he died on the day the meteor hit. When we look at the preservation of the leg and the skin around the joint bones, we’re talking about the day of the impact. or just before There was no advanced caries.

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DePalma and the dinosaur leg will be featured in two episodes of “Nova” on PBS airing back-to-back on Wednesday: “Dinosaur Apocalypse: The New Evidence” and “Dinosaur Apocalypse: The Last Day.” Biologist and natural historian Sir David Attenborough will host the programmes, which have been produced in conjunction with the BBC.

The leg and several other relics discovered at the North Dakota site are the first true fossils found showing the death and destruction that took place when a 10-mile-long space rock struck the Yucatán Peninsula in the Gulf of Mexico. This impact event 66 million years ago doomed the dinosaurs and led to the mass extinction of 75% of animal and plant life on Earth.

Back then, the world was a much warmer place. There were no ice caps and the water levels were higher. The North American continent was bisected by the Western Interior Seaway. Tanis is located on what used to be the edge of this massive river, which became a conduit for carnage after the asteroid struck. Shock waves from nearly 3,000 miles away caused the seaway to erupt with a tsunami of epic proportions.

As DePalma pointed out, Thescelosaurus never stood a chance.

“You wouldn’t want to be there that day,” he said. “There was a turbulent wall of death coming up the river. Moreover, all these incandescent spherules fall from the sky. They are like superheated glass beads that re-enter the Earth’s atmosphere after being ejected from the Yucatán crater site. Then there were all these earthquakes. It was truly hell on earth. »

The loss of a dinosaur, however, is a gain for a paleontologist. After the discovery of Tanis in 2008, scientists began to realize that the fossils were likely created there during this high-impact time. A series of key discoveries have been made, including the leg of a dinosaur, the embryo of a pterosaur still in its shell, a turtle pierced by a piece of wood and the well-preserved skin of a triceratops. Many of these fossils are shown to the public for the first time in PBS documentaries.

The fossilized fish discovered at the site in 2019, which surprised many scientists, is perhaps the most telling. In these petrified remains, the researchers found the embedded evidence they needed to support the claim that the animals died when the asteroid hit: the glass spheres, known as ejecta, that fell from heaven on that fateful day.

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“These are fish that died that day,” DePalma said. “We know because they had ejecta from the impact in their gills.”

Researchers have unearthed countless samples of these glass spheres, containing all the chemical constituents typical of a major impact event. Made of sand and other Earth materials, the molten glass was ejected into the atmosphere by the explosion caused by the asteroid hitting the planet — estimated to be the equivalent of 10 billion atomic bombs. Inside one of these circular fossils is a tiny grain of rock that may have come from the killer asteroid itself.

DePalma, a postgraduate researcher at the University of Manchester in England and assistant professor of geosciences at Florida Atlantic University, has led Tanis’ efforts since 2012. He and other scientists on the team have published several major papers describing the findings and describing the scientific methodology. used to date fossils and other evidence.

DePalma asserts that what happened then is directly relevant to the world today.

“I was asked, ‘Why should we care? The dinosaurs have been dead for so long,” he said. “It’s not just for paleo nerds. This applies directly to today. We are seeing mass deaths of animals and biomes that are under very stressful situations all over the world. Looking through this window to the past, we can apply these lessons to today.

To produce the “Nova” episodes, DePalma worked directly with one of his heroes – Attenborough, 96 – to review the findings and discuss their significance.

“Sir David and I interacted and consulted on everything,” DePalma said. ” It was a great experience. He cannot stifle his enthusiasm. When we looked at the fossils and talked about what they meant, you two couldn’t separate us. We kept talking about them. We would have stayed there all day if no one had stopped us.

“Dinosaur Apocalypse” airs Wednesday at 9 p.m. ET on PBS.

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