Diprotodon

*Diprotodon*, ( name meaning "two forward teeth"), is a genus of diprotodontid marsupial native to Australia during the Pleistocene epoch. The genus is currently considered monotypic, only containing Diprotodon optatum, the largest known marsupial to have ever existed. It is considered one of the core species of the "Australian megafauna", which ranged throughout the continent during the Pleistocene. Diprotodon existed from about 1.6 million years ago until extinction some 44,000 years ago.

In the episode, ***Monsters of the Outback***, a herd of Diprotodon were brought to the park from Late Pleistocene Australia, 65,000 years ago. They reside in a wetland enclosure.

## Facts

### Era and Discovery

Some modern researchers, including Richard Roberts and Tim Flannery, argue that diprotodonts, along with a wide range of other Australian megafauna, became extinct shortly after humans arrived in Australia about 50,000 years ago. Others, including Steve Wroe, note that records in the Australian Pleistocene are rare, and there is not enough data to definitively determine the time of extinction of many of the species, with many of the species having no confirmed record within the last 100,000 years. They suggest that many of the extinctions had been staggered over the course of the late Middle Pleistocene and early Late Pleistocene, prior to human arrival, due to climatic stress. *Diprotodon* is one of several species with confirmed dates post-dating human arrival on the continent, with the latest high-reliability date being around 44 kyr BP.

Some earlier researchers, including Richard Wright, argued on the contrary that diprotodont remains from several sites, such as Tambar Springs and Trinkey and Lime Springs, suggest that *Diprotodon* survived much longer, into the Holocene. Other more recent researchers, including Lesley Head and Judith Field, favour an extinction date of 28,000 to 30,000 years ago, which would mean that humans coexisted with *Diprotodon* for some 20,000 years. However, opponents of "late extinction" theories have interpreted such late dates based on indirect dating methods as artifacts resulting from redeposition of skeletal material into more recent strata, and recent direct dating results obtained with new technologies have tended to confirm this interpretation.

Three theories have been advanced to explain the mass extinction. The first recorded *Diprotodon* remains were discovered in a cave near Wellington, New South Wales, in the early 1830s by bushman George Ranken and Major Thomas Mitchell; the latter sent them to England for study by Sir Richard Owen In the 1840s, Ludwig Leichhardt discovered many *Diprotodon* bones eroding from the banks of creeks in the Darling Downs of Queensland, and when reporting the find to Owen, commented that the remains were so well preserved, he expected to find living examples in the then-unexplored central regions of Australia.

The majority of fossil finds are of demographic groups indicative of diprotodonts dying in drought conditions. For example, hundreds of individuals were found in Lake Callabonna with well-preserved lower bodies, but crushed and distorted heads. Several family groups are thought to have sunk in mud while crossing the drying lake bed. Other finds consist of age groupings of young or old animals, which are first to die during a drought.

In 2012, a significant group of about 40 was found at Eulo, south-west Queensland.

## Trivia

* The sound effects of *Diprotodon* are that of walrus, hippo, and rhino sound effects.
* Diprotodon is the largest marsupial brought to the park.