PROF. MIKE VOORHIES (University of Nebraska): Well I was walking up this gully looking for fossils, the way I'd walked up a thousand gullies before, keeping my eye on the ground looking for pieces of fossils that might have washed down in the rain the previous night and I scrambled up to the top and I saw something that completely astounded me, a sight that no palaeontologist has ever seen.
NARRATOR: It was a sight of sudden, prehistoric disaster. Voorhies's digging revealed the bones of 200 fossilised rhinos, together with the prehistoric skeletons of camels and lizards, horses and turtles. Dating showed they had all died abruptly 10 million years ago.
MIKE VOORHIES: It suddenly dawned on me that this was a scene of a mass catastrophe of a type that I'd never, never encountered before.
NARRATOR: The cause of death, however, remained a mystery. It was not from old age.
MIKE VOORHIES: I could tell by looking at the teeth that these animals had died in their prime. What was astounding was that here were young mothers and their, and their babies, big bull rhinos in the prime of life and here they were dead for no, no apparent reason.