Scientists solve mystery of how prehistoric beasts became extinct

Several thousands of years ago megafauna — including 7m-long lizards and wombats the size of cars — existed in Australia. Now, scientists have finally solved the mystery of how the large prehistoric beasts disappeared.

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Scientists have solved the mystery of why wombats the size of cars and other large prehistoric beasts disappeared from southeastern Australia.

For several thousand years, the first ancestors of Aboriginal Australians in NSW lived alongside megafauna, including 7m-long lizards, and kangaroos and birds twice the height of today’s average man.

Debate has raged over the fate of megafauna since the first fossils were found more than 100 years ago but scientists and mathematicians have finally found the answer — with the help of number-crunching supercomputers.

Massive ancient wombats the size of cars once roamed around Sydney.

Australia’s megafauna extinction about 42,000 years ago can only be explained by a combination of the arrival of humans and the reduced availability of freshwater due to climate change.

It was one of the oldest major extinction events anywhere in the world since modern humans evolved and left Africa.

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As the climate warmed and water holes dwindled, people and megafauna came in closer contact in search of a drink, which stacked the odds in favour of the human hunters, according to a report by scientists at the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage.

Palorchestes azael was a marsupial herbivore, which may have had a small trunk like tapirs. Picture: Illustration by Gabriel Ugueto

Back then, Sydney was several hundred kilometres from the coast on a supercontinent connected to Tasmania and New Guinea called “Sahul”.

The ancient Egyptians wouldn’t dream up the pyramids for another 40,000 years.

“The drying landscape concentrated megafauna into smaller areas and increased the likelihood hunters would cross paths with animals, which increased the success rate of hunting,” Flinders University environmental modeller Professor Corey Bradshaw said.

“The debate about why megafauna disappeared has fluctuated between the impact of people or climate change but we can now say definitively that it was both — a one-two punch.”

Dromornis stirtoni was the largest of the dromornithids, a group of huge flightless birds known only from Australia.

The Nullarbor is home to thousands of natural caves that have trapped Australian fauna over thousands of years. Picture: Raphael Eisenhofer

The study analysed fossil data, climate reconstructions and data from archaeological digs using sophisticated mathematical models to explain what happened when people and megafauna coexisted in southeast Australia, between Tweed Heads and Adelaide.

Climate models like those used to project what the future climate will be were used to look backwards in time, validated with cores from lake beds to analyse the vegetation through remaining specks of pollen.

Mathematical breakthroughs in the past few years and more fossil finds helped scientists finally firm up their statistics about human movement and megafauna extinction dates.

Across Australia, archaeologists have found more than 12,000 fossils from 350 different species of megafauna and other smaller animals.

Originally published as Scientists solve mystery of how prehistoric beasts became extinct