Visit one of Australia's most important fossil digs.


MURRAY SILBY: Millions of years ago, giant animals roamed this region of inland Australia. This is Alcoota, about 200 kilometres northeast of Alice Springs. At this scientific reserve, one of Australia's most significant fossil digs is taking place.

DIRK MEGIRIAN: The outstanding thing about this site is its richness. It doesn't have the species richness of some of the other sites but the amount of bone material is huge.

MURRAY SILBY: After millions of years of being entombed in the earth, the remains of long-extinct animals are being uncovered by a team of scientists from the museum and art gallery of the Northern Territory. They've been coming here for years - excavating the bed of fossil bones - trying to reveal the secrets of some of Australia's oldest megafauna.

DIRK MEGIRIAN: There's enough material to really reconstruct the appearance of these animals. How they moved, how fast they moved, their body weights and so on.

MURRAY SILBY: It's believed thousands of animals perished here at Alcoota and their remains lie just beneath the surface of this mass grave.

DIRK MEGIRIAN: There are one or two other sites about the same age but they're not very rich so their value in terms of giving us a bit of a geographic spread across the continent but the amount of material available from them is extremely small so this is, you know, unique in that sense.

MURRAY SILBY: Thousands of fossils collected from the Alcoota site, are held at the Museum of Central Australia. Among them are the bones of giant crocodiles, geese more than two metres tall, and thylacines, or Tasmanian tigers.

As well as clues to Australia's megafauna, the dig is providing an insight into what this landscape could have looked like millions of years ago.

Researchers say the arid land was once covered in shrubs and trees.

PETER LATZ: What we've got here mainly now is a lot of grassland which keeps the cattlemen very happy but in those days these were mostly browsers so it was a mixture of trees and shrubs and practically no grass I wouldn't think. Very different.

MURRAY SILBY: The excavation of the ancient site is taking place in two sections. One on a small hill that's revealing fossils from around five million years ago and the second, a depression in the ground, dating three to four million years. It's this dig, that researchers say is proving extremely challenging. What's making the job more difficult is that this is effectively a mass grave for a whole range of animals whose remains are tangled amongst each other after falling victim to a typical boom-bust period. It's painstaking work, piecing together this scientific puzzle. Researchers camp on site for months at a time.

It's gruelling and delicate work, but the team is committed to documenting this remarkable story.

The Alcoota site contains enough material to keep researchers busy for many years. They're driven by the desire to understand a unique period in Australia's prehistory and the chance to fill in the gaps of this country's evolutionary story.