At Bullock Creek, located about 550km to the south of Darwin in the Northern Territory of Australia, the Camfield Fossil Beds contain a rich assemblage of extinct species of marsupials, birds, reptiles and fishes. The well preserved fossils are contained within beds of limestone and have been dated to about 12 million years ago, in the middle Miocene epoch. Among the fossils at the Bullock Creek site are a large extinct crocodile known as Baru, a primitive large kangaroo and Meiolania, a giant horned turtle. Neohelos, a marsupial 'rhinoceros' and Bullockornis, a large flightless bird, are also present in significant numbers. The fossils provide evidence for the evolution of Australian fauna and demonstrate how the climate and ancient environment has changed.