Sir David Attenborough said that new evidence about the dinosaurs' last day on Earth has been uncovered while filming his new BBC documentary.
An asteroid - known as Chicxulub - hit the planet around 66 million years ago and wiped out the dinosaurs.
And now he fossil of one of the dinosaurs believed to have been killed by the giant comet has been uncovered.
The preserved leg of a dinosaur was discovered while the natural historian, 95, and his crew explored the Tanis fossil site in North Dakota.
They were there for three years to film Dinosaurs: The Final Day, which includes an investigation into the devastating asteroid.
A fragment of the meteor's rock has been found preserved within part of a fish fossil at the dig site.
Attenborough and his team were granted exclusive access, and he said: "The film is about the last day the dinosaurs lived on Earth - and the minute by minute detail of that day.
"We tend to think that the end of a (geological) period extends over decades, if not centuries, and actually the end of a period may vary around the world in different areas."
He however said that what's "remarkable" about the subject is that "it was one astonishingly huge event that was worldwide." He then commented on the asteroid itself.
He commented recently: "An object the size of Mount Everest hit the Earth and that was the end of the Cretaceous - and that's an extraordinary thing to happen."
Attenborough said that it's further "extraordinary" for having caused the end of the dinosaurs, with him stating that their extinction prompted life on the planet "to restart."
He recalled the moment when tests showed the chemical profile of the suspected rock matched that of the asteroid. He said it was a "moment of justification for the while thing."
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The broadcaster - who is currently narrating the Dynasties II series - said that information produced from the work of the scientists made the extinction event "very vivid indeed."
The natural historian further commented that it was "extraordinary" to hold the spherule in his hand, knowing that it had fallen "within hours of the asteroid impact."
He said that it's evidence of the event that caused 75 percent of species on the planet to disappear, suggesting that his heart beat particularly fast when holding it.
It's understood that special visual effects will transport him back in time to the late Cretaceous period, before recreating the events of the last day of the dinosaurs.
Attenborough, palaeontologist Robert DePalma and BBC Studios explored the Tanis fossil site over three years.
Dinosaurs: The Final Day will air on BBC One next Friday (April 15).
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