They are separated by a vast ocean and by millions of years, but tiny prehistoric bones found on an Australian farm have been directly linked to a strange and secretive little animal that lives today in the southern rainforests of South America. The fossilised ankle and ear bones are those of Australia's earliest known marsupial, Djarthia, a primitive mouse-like creature that lived 55 million years ago. It is a kind of Australian Eve, possibly the mother of all the continent's unusual pouched mammals, such as kangaroos, koalas, possums and wombats.