An Ancient Herbivore's Toolkit
Eight million years ago, during the late Miocene epoch, central Australia was not the arid region it is today. It was a subtropical open woodland, where a diverse range of animals, including the marsupial Kolopsis torus. This creature, a mid-sized member of the extinct Diprotodontidae family, was a relative of modern wombats and koalas. It grew to about 1.5 meters long and stood 80 centimeters tall at the shoulder.
The jaw of Kolopsis shows its place in this ancient ecosystem. It was a generalist browser, using its teeth to eat the leaves, stems, and shoots of forest plants. Its dental structure, particularly a complex upper premolar with multiple cusps, identifies it as a zygomaturine diprotodontid. This group of marsupials was highly successful and more numerous than kangaroos during the Miocene. The fossils, including complete skulls and jaws, are primarily found at Alcoota Station, a site 200 kilometers northeast of Alice Springs. These remains show an animal adapted to a world that was gradually becoming cooler and drier.
Life and Death at a Miocene Waterhole
The fossils of Kolopsis torus are found almost exclusively at the Alcoota Fossil Beds. This site is a Lagerstätte, a sedimentary deposit with exceptionally preserved fossils. The remains are concentrated in a massive "bone bed," where the bones of thousands of animals are densely packed together. This suggests a catastrophic event, likely a severe drought, that drew countless animals to a shrinking waterhole where they eventually perished.
Kolopsis did not live alone. It shared this environment with an array of other large animals. Predators included the wolf-sized thylacine, Thylacinus potens, and a marsupial lion called Wakaleo alcootense. Perhaps the most imposing contemporary was Dromornis stirtoni, one of the largest birds known to have existed, standing up to 3 meters tall. The Alcoota site shows this entire community, showing the interactions between herbivores like Kolopsis and the carnivores that hunted them. The fossils are now housed and studied at the Museum and Art Gallery of the Northern Territory.