The genus Phascolarctos consists of 3 species, of which only one (P. cinereus, the Koala) is alive today. The largest species was P. stirtoni (or Giant Koala) that lived in the Pleistocene epoch. Giant Koala species are known only from fossils found in the Lake Eyre and Tarkarooloo basins of South Australia. Not much is known of the P. maris species.