Giant, Predatory Lizard Fossil Reveals a Bit More about Early Australians

First Posted: Sep 23, 2015 07:21 PM EDT

It turns out that Australia's first human residents may have had to deal with giant, killer lizards. Scientists have found that Australia's early human inhabitants and giant apex predator lizards actually 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," said Gilbert Price, one of the researchers, in a news release. "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 researchers used radiocarbon and uranium thorium techniques to date the bone to about 50,000 years old. This time coincided with the arrival of Australia's Aboriginal inhabitants.

The bone itself could be from a Komodo dragon, or from an even bigger species like the extinct Megalania monitor lizard, which grew up to six meters long and weighed about 500 kg.

"It's been long-debated whether or not humans or climate change knocked off the giant lizards, alongside the rest of the megafauna," said Price. "Humans can only now be considered as potential drivers of their extinction."

Currently, the researchers aren't sure how the lizard bone got into the cave in the first place, which houses millions of bones of many rodents, regurgitated by owls. However, the findings do show that when it comes to these lizards, it's possible that humans may be behind their steep decline.

The findings are published in the journal Quaternary Science Reviews.