Sydney, Sep 24 (IANS): During the last Ice Age, Australia's first human inhabitants had to contend with giant killer lizards, reveals new research that unearthed fossils of giant killer lizards.

The researchers used radiocarbon and uranium thorium techniques to date the fossils as about 50,000 years old, coinciding with the arrival of Australia's Aboriginal inhabitants.

The findings suggest that humans may have driven these killer lizards to extinction.

"Our jaws dropped when we found a tiny fossil from a giant lizard during a two metre deep excavation in one of the Capricorn Caves, near Rockhampton," said one of the researchers Gilbert Price from University of Queensland.

"The one-centimetre bone, an osteoderm, came from under the lizard's skin and is the youngest record of a giant lizard on the entire continent," he noted.

"The find is pretty significant, especially for the timeframe that it dates," Price said.

Price said massive lizards and even nine-metre long inland crocodiles roamed Australia during the last Ice Age in the Pleistocene geological period.

"It has been long-debated whether or not humans or climate change knocked off the giant lizards," he said.

"Humans can only now be considered as potential drivers of their extinction," he noted.

The research was published in the journal Quaternary Science Reviews.