Imagine a vast, lush forest dominated by giant flightless birds and crocodiles. This was Australia’s Red Centre 25 million years ago. There lived several species of koala; early kangaroos the size of possums; and the wombat-sized ancestors of the largest-ever marsupial, Diprotodon optatum (around 2.5 tonnes).
A window onto this ancient time is provided by a little-studied fossil site near Pwerte Marnte Marnte, south of Alice Springs in central Australia. This late Oligocene site yielded the earliest-known fossils of marsupials that look similar to modern ones, as well as fossils from wholly extinct groups such as the enigmatic ilariids, which were something like a koala crossed with a wombat.
