Scientists extract extinct giant kangaroo DNA

Eric Hopton for redOrbit.com Your Universe Online

The Australian red kangaroo is a big powerful animal but the science of DNA extraction has helped paint a picture of one of its ancient ancestors that makes the red look like a puny geek.

Take a red kangaroo, then double or triple its size to around ten feet in height and over 500 pounds in weight. Next, give it a set of large, nasty, hoof-like claws and then hit it in the face with a shovel. What you finish up with should resemble the long extinct giant short-faced kangaroo. This was the largest kangaroo to walk the Earth and, with its flat face and forward-pointing eyes, it was a strange looking beast.

Scientists have finally managed to extract DNA from some of these giant kangaroos the mysterious marsupial megafauna that roamed Australia over 40,000 years ago.

A team of scientists led by Dr Bastien Llamas and Professor Alan Cooper from the University of Adelaides Australian Centre for Ancient DNA (ACAD) have extracted DNA sequences from two species: the Giant Short-faced (Simosthenurus occidentalis) and a giant wallaby (Protemnodon anak).

These two fossils were discovered in a Tasmanian cave. The bones came from animals that died around 45,000 years ago. The cold dry cave provided good preservation conditions in the cave. This allowed enough short pieces of DNA to survive for the research team to reconstruct partial mitochondrial genomes which are genetic messages passed from mother to offspring. Mitochondrial genomes are commonly widely used to establish evolutionary relationships between fossil species.

The ancient DNA reveals that extinct giant wallabies are very close relatives of large living kangaroos, such as the red and western grey kangaroos, says lead author Dr. Bastien Llamas, ACAD senior research associate. Their skeletons had suggested they were quite primitive macropods a group that includes kangaroos, wallabies, pademelons and quokkas but now we can place giant wallaby much higher up the kangaroo family tree.

The research has also confirmed that short-faced kangaroos are a highly distinct lineage of macropods, which had been predicted on their unusual anatomy.

Scientists have previously obtained complete nuclear or mitochondrial genomes from extinct megafauna in Eurasia, the Americas, and New Zealand. Fossils of the giant short-faced kangaroo, like the Naracoorte World Heritage fossil deposits found in South Australia, have been discovered in many parts of Australia, including the, Lake Menindee in New South Wales, Darling Downs in Queensland. But the poorer preservation conditions and the age of Australian megafauna remains have meant that retrieval of its DNA has been impossible until now, leaving scientists just bones for analysis.

In addition to poor DNA preservation, most of the extinct Australian megafauna do not have very close relatives roaming around today, which makes it more difficult to retrieve and interpret the genetic data, says Dr. Llamas. Together with my colleagues Alan Cooper and Paul Brotherton, we had to think hard about experimental and bioinformatics approaches to overcome more than 10 million years of divergent evolution between the extinct and living species.

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Scientists extract extinct giant kangaroo DNA