In the Badlands of North Dakota, scientists think they might have found the fossilized remains of animals killed on the day an asteroid struck Earth 66 million years ago. The evidence points to a catastrophic event, with a jumble of rare fossils, including a pterosaur embryo still in its shell and a well-preserved patch of triceratops skin mixed in with tiny spheres of clay and glass that could be the fallout from the massive asteroid impact. Sir David Attenborough guides us on a search for clues that could give an unprecedented snapshot of what happened in the dinosaurs' final moments on Earth.