First Humans in Australia Lived Alongside Giant Predator Lizards

Giant carnivorous lizards shared turf with the earliest human settlers in Australia, according to a new study.

Research led by the University of Queensland have dated a 1 centimeter lizard bone to be around 50,000 years old, which coincides with the arrival of Australia's first Aboriginal inhabitants.

The scientists used radiocarbon and uranium thorium techniques to date the fossil to the Pleistocene period. This geological epoch lasted from 2.6 million to 11,700 years ago and saw 9 meter long crocodiles roaming Australia, according to Gilbert Price, vertebrate palaeoecologist at the University of Queensland and the study's lead author.

Research news site Science Daily reported that Price and his colleagues cannot decide whether the bone belonged to a komodo dragon—that once roamed Australia but is now confined to several Indonesian islands—or a much larger lizard. Price says it could have belonged to the Megalania monitor lizard. Megalania, which are now extinct, grew up to 6 metres long, weighed around 500 kg and may have eaten large mammals, as well as other reptiles and birds.

The study, published in Quaternary Science Reviews, proves for the first time that humans and giant lizards were present in Australia during the same time period. Humans can thus hypothetically be considered a driver of extinction of giant monitor lizards, though the study does not suggest how this might have happened.

The fossil, which is at least 30,000 years younger than other giant lizard fossils found in Australia, was discovered in the Colosseum Chamber, part of a fossil-rich site known as the Capricorn Caves in the Mount Etna region in Queensland.

In 2003, human remains discovered at Lake Mungo in New South Wales were analysed and researchers concluded that they provided evidence for human life between 50,000 and 46,000 years ago. Megafauna in Australia are widely believed to have become extinct due to climatic changes as a result of the most recent Ice Age, which occurred during the Pleistocene epoch. However, some studies have linked their global extinction at least partially to human intervention.