Riversleigh is the most famous fossil formation in Australia. Dating from the Oligocene to the Miocene epochs, it bears fossils of frogs, lizards, and birds, but most notably mammals. These mammals included ancient koalas, kangaroos, precursors to the Thylacine (the Tasmanian Tiger, relatives of the Marsupial lion, and Obdurodon—a gigantic prehistoric relative of the modern platypus—among other extinct mammals from prehistory.