Australia’s early human inhabitants had to contend with giant killer lizards, according to a team of paleontologists from the University of Queensland, Southern Cross University and Queensland Museum.

The team, directed by Dr Gilbert Price of the University of Queensland, unearthed the first evidence that Australia’s first human inhabitants and giant apex predator lizards had overlapped.

“Our jaws dropped when we found a tiny fossil from a giant lizard during a two meter deep excavation in one of the Capricorn Caves, near Rockhampton, Queensland” said Dr Price, lead author of a paper to be published in the October 2015 issue of the journal Quaternary Science Reviews.

“The one-centimeter bone, an osteoderm, came from under the lizard’s skin and is the youngest record of a giant lizard on the entire continent.”

The scientists used radiocarbon and uranium thorium techniques to date the bone as about 50,000 years old, coinciding with the arrival of Australia’s first human inhabitants.

“The new monitor fossil is, minimally, 30,000 years younger than the previous youngest reliably dated record for giant lizards in Australia and for the first time, demonstrates that on a continental scale, humans and giant lizards overlapped in time,” they said.

“We can’t tell if the bone is from a Komodo dragon — which once roamed Australia — or an even bigger species like the extinct Megalania monitor lizard (Megalania prisca), which weighed about 500 kg and grew up to 20 feet (6 m) long,” Dr Price said.

“Even 30 foot (9 m) long inland crocodiles roamed Australia during the last Ice Age in the Pleistocene geological period,” he added.

“We unequivocally demonstrate that humans and giant monitor lizards overlapped temporally in Australia, and thus, humans can only now be considered potential drivers for their extinction,” the scientists concluded.

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Gilbert J. Price et al. 2015. Temporal overlap of humans and giant lizards (Varanidae; Squamata) in Pleistocene Australia. Quaternary Science Reviews, vol. 125, pp. 98-105; doi: 10.1016/j.quascirev.2015.08.013