Page "Tasmanian devil" Paragraph 7

The roots of Australian marsupials are thought to trace back tens of millions of years to when much of the current southern hemisphere was part of the supercontinent of Gondwana ; marsupials are believed to have originated in what is now South America and migrated across Antarctica, which had a temperate climate at the time.

As soil degradation took hold, it is believed that the marsupials adapted to the more basic flora of Australia.

According to Pemberton, the possible ancestors of the devil may have needed to climb trees to acquire food, leading to a growth in size and the hopping gait of many marsupials.

He speculated that these adaptations may have caused the contemporary devil's peculiar gait.

The specific lineage of the Tasmanian devil is theorised to have emerged during the Miocene, molecular evidence suggesting a split from the ancestors of quolls between 10 and 15 million years ago, when severe climate change came to bear in Australia, transforming the climate from warm and moist to an arid, dry ice age, resulting in mass extinctions.

As most of their prey died of the cold, only a few carnivores survived, including the ancestors of the quoll and thylacine.

It is speculated that the devil lineage may have arisen at this time to fill a niche in the ecosystem, as a scavenger that disposed of carrion left behind by the selective-eating thylacine.

The extinct Glaucodon ballaratensis of the Pliocene age has been dubbed an intermediate species between the quoll and devil.

A jawbone found in the mainland Jenolan Caves Fossil deposits in limestone caves at Naracoorte, South Australia, dating to the Miocene include specimens of S. laniarius, which were around 15 % larger and 50 % heavier than modern devils.

Older specimens believed to be 50 – 70, 000 years old were found in Darling Downs in Queensland and in Western Australia.

It is not clear whether the modern devil evolved from S. laniarius, or whether they coexisted at the time.

Richard Owen argued for the latter hypothesis in the 19th century, based on fossils found in 1877 in New South Wales.

Large bones attributed to S. moornaensis have been found in New South Wales, and it has been conjectured that these two extinct larger species may have hunted and scavenged.

It is known that there were several genera of thylacine millions of years ago, and that they ranged in size, the smaller being more reliant on foraging.

As the devil and thylacine are similar, the extinction of the co-existing thylacine genera has been cited as evidence for an analogous history for the devils.

It has been speculated that the smaller size of S. laniarius and S. moornaensis allowed them to adapt to the changing conditions more effectively and survive longer than the corresponding thylacines.

As the extinction of these two species came at a similar time to human habitation of Australia, hunting by humans and land clearance have been mooted as possible causes.

Critics of this theory point out that as indigenous Australians only developed boomerangs and spears for hunting around 10, 000 years ago, a critical fall in numbers due to systematic hunting is unlikely.

They also point out that caves inhabited by Aborigines have a low proportion of bones and rock paintings of devils, and suggest that this is an indication that it was not a large part of indigenous lifestyle.

A scientific report in 1910 claimed that Aborigines preferred the meat of herbivores rather than carnivores.

The other main theory for the extinction was that it was due to the climate change brought on by the most recent ice age.