The broadcaster and naturalist’s latest project highlights fossilized remains of a Thescelosaurus believed by scientists to have been killed by the Chicxulub asteroid 66 million years ago.
A fragment of the rock may also have been found, preserved within a tiny “spherule” of clay, at the Tanis fossil site in North Dakota that the TV show is centered around.
Sir David, who alongside his team was granted exclusive access to the site, 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.
“But what’s remarkable about this, is that it was one astonishingly huge event that was worldwide.
“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.
“And of course it’s extraordinary too because it caused the end of the dinosaurs. And the life on this planet had to restart.”
Sir David, 95, recalled the “electric moment” when tests showed the chemical profile of a “spherule” matched that of the asteroid.
“It was a moment of justification for the whole thing really,” he said.
The broadcaster said information gleaned from the work of the scientists made the extinction event “very, very vivid indeed.”
He added: “Because when you see the spherules in the gills of the fish it is extraordinary to understand the nature of that evidence, it is extraordinary to hold that in your hand and say ‘this spherule fell within hours of the asteroid impact’.
“This is evidence of the event that caused 75 per cent of species on earth to disappear. And you have a heart of flint not have it beat just a little faster when you’re faced with that sort of thing.”
The documentary will see Sir David, palaeontologist Robert DePalma and BBC Studios cameras exploring the Tanis site over three years.
Special visual effects will transport Sir David back in time to the late Cretaceous period to witness the creatures who lived at Tanis, before recreating the events of the last day of the dinosaurs.
Dinosaurs: The Final Day with Sir David Attenborough will be broadcast on BBC One on April 15.
Sir David faced dominated Piccadilly Circus’s advertising screens for a special takeover as the veteran broadcaster alerted commuters about the importance of plants and their integral role in the survival of the planet in February.
The naturalist dominated Europe’s largest advertising display for 20 minutes as he promoted a digital experience inspired by his latest documentary series The Green Planet.
In addition to Sir David’s announcement, the Shaftesbury Memorial Fountain, also known as the Fountain of Eros, in Piccadilly Circus was transformed into a plant installation, with flowers and foliage covering its steps.
George Holan is chief editor at Plainsmen Post and has articles published in many notable publications in the last decade.