University of Queensland palaeontologist Gilbert Price said the fossil was found by masters student Bok Khoo, from the University of NSW, during a dig last month.
“It would have been a monster, bigger than anything we have likely seen before,” the Courier Mail quoted Dr Price as saying.
“Possibly the biggest in Australia. It did not have any teeth attached but the tooth sockets alone were 35mm-40mm wide so you can imagine the teeth it had,” he said.
The front lower jaw bone was found near an abandoned road crossing along the Leichhardt River, near Floraville station, on July 10.
It was found in an ancient riverbed deposit formed during the Pliocene and Pleistocene periods, one to two million years ago.