- Written by Nadia O'Carroll
Diprotodon optatum was the largest marsupial that has ever lived, the largest males were 2 m tall at the shoulder, 3m long and weighed up to 2500kg, females were much smaller and weighed up to 1000kg.
This animal really has no modern equivalent, but its closest living relatives are wombats and koalas.
It is believed that Diprotodon was relatively common and widespread in a variety of habitats in Australia, its bones have also been found in Papua New Guinea. In 1840s when explorer Ludwig Leichhardt was travelling through the Darling Downs, he saw so many Diprotodon bones in the creek banks, that he fully expected to encounter these huge creatures farther inland. The number of Diprotodon skeletons, tracks and pathways that have been discovered and studied have allowed us to learn much about this long extinct creature.
The Diprotodon had the same heavy build and size as a rhinoceros or hippopotamus, but unlike these animals it was covered with hair similar to a wombat. It stood on massive pillar-like legs, with broad footpads and strong claws and its stance was pigeon-toed. Despite its stocky build and thick legs it could probably travel at about the same speed as a camel.
Diprotodon had a massive head, a short tapir-like trunk, strong jaws armed with two large upper tusk-like front teeth. These huge teeth were not used for hunting, because Diprotodon was herbivore, which utilised these teeth, to dig and browse on the leaves, stems, and branches of trees and shrubs. The powerful jaws and large molars the size of a human fist, were also needed to crush tough vegetation.
As a marsupial Diprotodon gave birth to immature young which were then carried and suckled in a backward facing pouch. The young Diprodoton would have probably stayed with its mother for several years.
It is believed Diprotodons would have lived in family groups or small herds. Some male skeletons show battle scars, which provide evidence that males may have fought for domination of the herd. The social system could have been one dominant male living with a harem of females (polygynous breeding) or possibly a matriarchal system similar to elephants, where females and young live together in a herd and males are solitary.
Diprodotons first appeared in Australia 1.6 million years ago and were a relatively common species until their extinction between 40000 to 25000 years ago. The Diprodoton would have had some natural predators – Tasmanian Devils and Tasmanian Tigers were found throughout the mainland, the formidable Marsupial Lion, crocodiles and a Giant goanna. However the likely major cause of the Diprodoton’s disappearance was the arrival of humans. Humans would have hunted large non-aggressive species such as Diprodotons, and slow reproduction would have made its populations vulnerable. Human landscape modification through burning practices, would also have destroyed, damaged and reduced the ecosystems on which these giant browsers depended.