Large kangaroos today roam long distances across the outback, often surviving droughts by moving in mobs to find new food when pickings are slim.

But not all kangaroos have been this way. In new research published today in PLOS One, we found giant kangaroos that once lived in eastern Australia were far less mobile, making them vulnerable to changes in local environmental conditions.

We discovered fossilised teeth of the now extinct giant kangaroo genus Protemnodon at Mount Etna Caves, north of Rockhampton, in central eastern Queensland. Analysing the teeth gave us a glimpse into the past movements of these extinct giants, hundreds of thousands of years ago.

Our results show Protemnodon did not forage across great distances, instead living in a lush and stable rainforest utopia. However, this utopia began to decline when the climate became drier with more pronounced seasons – spelling doom for Mount Etna’s giant roos.

The Mount Etna Caves National Park and nearby Capricorn Caves hold remarkable records of life over hundreds of thousands of years.

Fossils accumulated in the caves because they acted like giant pitfall traps and also lairs of predators such as thylacines, Tasmanian devils, marsupial lions, owls, raptors and the now-endangered

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