The long-running debate over what drove most of the world’s Ice Age megafauna to extinction has taken a dramatic turn with new research published in June in the Proceedings of the National Academy of Sciences USA.
The findings of an international team of researchers, led by palaeontologist Dr Gavin Prideaux of Flinders University, suggest human hunting caused the extinction of the largest kangaroo ever to evolve.
Dr Prideaux said the most detailed study yet made of the dietary habits of an extinct marsupial suggest that neither a drying climate nor firing of vegetation by humans drove the extinction of the largest kangaroo ever to evolve, the 230 kilogram short-faced Procoptodon goliah.
“Opinions have been divided between the importance of increasing aridity and landscape burning or hunting by humans, who arrived in Australia around 50,000 years ago,” Dr Prideaux said.
“Our research confirms the giant kangaroo fed mostly on saltbushes that were widely available, thrive in dry conditions and form stands that don’t carry fire well,” he said.
“We also established that the giant kangaroo needed to drink more regularly than its grazing contemporaries, and yet it disappeared during a period wetter than others it had survived previously.
“By playing down the roles of aridity and landscape burning, we refocus attention again on human hunting as a more likely extinction cause.”
The team, which included researchers from the Australian National University and Utah, Vanderbilt and East Tennessee State Universities in the US, studied the anatomy of a Procoptodon goliah skeleton, as well as microscopic scratches on teeth, and oxygen and carbon isotopes contained in tooth enamel.
They believe that as the largest ever hopping animal, the giant kangaroo would have been slower to accelerate from a standing start than other kangaroos making it more vulnerable to hunting by humans as the giant kangaroos ventured to waterholes to drink.
Australia, which was once home to rhinoceros-sized herbivores, marsupial ‘lions’ and giant lizards, suffered the worst extinctions of all the continents, losing 90 per cent of larger species by 40,000 years ago.
The research project was supported by the US National Science Foundation and the Australian Research Council.
Image reproduced with permission of the artist, Peter Trusler and the Australian Postal Corporation. The original work is held in the National Philatelic Collection, Melbourne.