In 1992 the fossil remains of the world's largest marsupial - the Diprotodon - were discovered on the bank of the river by Trevor Westlake ( a founding committee member of the Friends of the Lower Field River).
It has been suggested that the seeds were formerly dispersed by the now-extinct Diprotodon, on the basis that many Australian marsupials are adapted to cope with the toxins in Australian plants.
Australian megafauna including 3 metre high kangaroos and Diprotodons were found in the area until extinction about 13,000 years ago at the end of the ice age.
Pleistocene Australia supported large Short-faced kangaroo (Procoptodon goliah), Diprotodon (a giant wombat), the Marsupial Lion (Thylacoleo carnifex), the flightless birds Genyornis and Dromornis, the 5-meter snake Wonambi and the giant lizard, the megalania.