Australia once had a wombat the weight of a small car
Diprotodon, a marsupial shaped like a giant wombat, stood two metres at the shoulder and weighed up to 2,780 kilograms. It shared Pleistocene Australia with a kangaroo taller than a person and a marsupial lion. Nearly all of these giants vanished, and scientists still argue fiercely over whether people or climate killed them.
Elsewhere, megafauna usually means animals of 100 kilograms or more, but Australia's giants were smaller than other continents', so a threshold of 40 kilograms is often used. Diprotodon was the largest marsupial that ever lived and the only one known to have migrated seasonally. Procoptodon goliah, the giant short-faced kangaroo, grew two to three metres tall and up to 230 kilograms. Thylacoleo, the marsupial lion, had a catlike skull, slicing teeth and a retractable thumb claw, and was about the size of a lioness. There was also a sheep-sized echidna and a koala a third larger than today's.
One camp, including Tim Flannery, argues that arriving humans, through hunting and landscape burning, drove the extinctions. Dating using luminescence and uranium-thorium methods suggested all mainland megafauna disappeared rapidly around 46,000 years ago, soon after people arrived. Scorch marks on eggshell fragments from over 200 sites were hailed as evidence that humans cooked the eggs of Genyornis, a flightless bird.
Each claim has been challenged. Another study found that 50 of 88 megafaunal species have no dates later than about 130,000 years ago, with firm evidence of overlap with people for only 8 to 14 species. Critics note the burnt eggs are too small for Genyornis and may belong to a smaller extinct megapode. Steve Wroe and others argue that climatic stress picked species off in stages, much earlier. A Zygomaturus fossil from the Willandra Lakes dated to 33 to 37 thousand years ago shows at least some giants lingered long after humans arrived.
A 2021 study added a twist: generalist species tended to vanish earlier, while highly specialised ones hung on longer or still survive, pointing to a mosaic of human and environmental pressures. The thylacine outlasted the rest into modern times, the last known one dying in 1936.
Source: Australian megafauna
