8 July 2022

What happened to Australia's massive wombats? Botanic Gardens event explores megafauna fate

| James Coleman
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Woman with a Diprotodon display

Diprotodons are thought to have become extinct about 7000 years ago. Photo: James Horan, Australian Museum.

Amateur naturalist Henry James McCooey is thought to be the first white man to spot Australia’s long-fabled yowie while exploring the hinterland between Ulladulla and Batemans Bay in December, 1882.

“It was tailless and covered with very long black hair, which was of a dirty red or snuff-colour about the throat and breast,” he wrote in The Australian Town and Country Journal.

“On the whole it was a most uncouth and repulsive-looking creature, evidently possessed of prodigious strength, and one which I should not care to come to close quarters with. Having sufficiently satisfied my curiosity, I threw a stone at the animal, whereupon it immediately rushed off.”

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Regardless of what you think of the urban legend, Australia was once teeming with large mammals. Palaeontologist and author Dr Lyndall Dawson has been digging them up for 50 years, and she’ll be talking about her findings at the Australian National Botanic Gardens this week.

“There are plenty of records,” she says.

“From about two million years to half a million years ago, there were some very large mammals in most of the continents. Here in Australia, we had a few extremely large marsupials which aren’t with us anymore. And there has been long-standing debate about why.”

Child standing next to a model Megalania

Megalania and friend. Photo: Australian National Botanic Gardens.

In Australia, examples of “megafauna” included the 2.8-tonne wombat-shaped diprotodon and giant goanna megalania. In Europe, it was the woolly rhinoceros, mammoth, cave lion and cave bear, while in North America, there was the giant ground sloth and sabre-toothed tiger.

Only Africa’s big animals are survived by the elephant, giraffe, rhinoceros and hippopotamus.

Dr Dawson was studying zoology at the University of New South Wales in the 1970s, just as the topic of megafauna was taking off around the world. Her interest was piqued and she turned to Australia’s examples for her PhD, starting with the first fossil of the diprotodon. This was discovered in the Wellington Caves in NSW in 1830 and is now preserved at the National Museum of Australia in Canberra.

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“I wanted to know why these animals got so big, how they fitted into our environment and what role they played in the ecological system, what contributed to their extinction, and what was the climate situation at the time,” she says.

She discovered that when First Nation’s people first arrived in Australia 60,000 years ago, they would have met all the marsupial animals that we are familiar with today but also shared the continent with several giant marsupial species.

Diprotodon fossil

The first fossil of the diprotodon was uncovered in the Wellington Caves in NSW. Photo: Howard Hughes, Australian Museum.

At the end of the last ice age 10,000 years ago, Australia’s climate is thought to have changed from cold-dry to warm-dry. As a result, surface water became scarce and the inland lakes – such as Lake Eyre – dried up during the warmer seasons. Most large, predominantly browsing animals lost their habitat and retreated to a narrow band in eastern Australia, where there was permanent water and better vegetation.

For instance, it’s thought the diprotodon may have survived on the Liverpool Plains of NSW until about 7000 years ago.

The final straw for the megafauna isn’t clear, but we’re getting closer to an answer.

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“People blame climate change, bushfires and hunting. Others say that Aboriginal people would never kill off a species because they look after their environment,” Dr Dawson says.

The fact the animals were alive for so long after humans first arrived does hint at climate-related problems, but both the Americas and Australia contain a clear connection between the extinction of animals and people arriving.

“Unlike Africa, where the early humans and animals would have grown up in harmony with each other.”


The diprotodon display at the National Museum of Australia. Photo: Abram Powell, Australian Museum.

Dr Dawson’s talk at the Botanic Gardens on 12 July 2022 will provide an update on where the study is up to.

“A lot of people think that what happened a hundred thousand years ago isn’t relevant to us, but I see humans as another species of megafauna,” she says.

“We have supplanted the place in the ecosystem those big species used to occupy. It will help us understand the impact we are having on our environments and how best to respond to that.”

The talk will be held at the Botanic Gardens Theatrette in Acton on Tuesday, 12 July at 12:30 pm. Her recent book, Tunnels in Time: the discovery, ecology & extinction of Australia’s marsupial megafauna will also be for sale at the Botanic Gardens bookshop. Book online.

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