Kangaroos barometer of climate change

Kangaroo evolution is a barometer of climate change in Australia and could help determine how local fauna may be affected in the future, a new study shows.

Using skeletons of modern and fossil species, a Flinders University palaeontologist and a Murdoch University anatomist have pieced together a detailed kangaroo family tree.

Flinders University's Gavin Prideaux says there have been hints of key stages in the evolution of the animals, but their whole story has not been put together until now.

Kangaroos and wallabies have long been recognised as potentially ideal barometers of historical climatic change in Australia, Dr Prideaux said.

They have been around for at least 30 million years, but difficulties in working out which species are related and when certain lineages evolved have hampered research for more than a century.

"We are now able to say that many of the key stages within the evolution of the group actually match quite closely with key stages in the evolution of Australia's climate," Dr Prideaux said.

When Australia was covered in forest and wetter and warmer 25 million years ago, small kangaroos lived in the undergrowth.

They took over as one of the dominant animals after Australia started to become drier 15 million years ago.

Getting the kangaroo story together could help scientists look at the impact contemporary climate change will have on Australia's remaining fauna, he said.

"It is very difficult to make any reasonable predictions based on really short-term data. You need long-term data provided by the fossil records on what kind of impact these changes can have on ... Australian animals."

Another result of their study showed that a tiny wallaby called the merrnine, which lives today on two islands off Shark Bay in Western Australia has been evolving on its own line, completely unrelated to other macropods, for about 20 million years.

"We know very little about the biology and the ecology of the animal, but it is really significant from an evolutionary perspective because its lineage evolved in the early days of the evolution of kangaroos."

"It is something really unique, we have only one left and it is endangered."

Their findings are published this month in the Zoological Journal of the Linnean Society.