Koala found to be related to ancient Australia's giant predator

However, scientists have for the first time obtained molecular evidence that these animals are much more closely related than had been thought. The study is published in the journal Proceedings of the Royal Society B: Biological Sciences.

An international team led by Dr Michael Buckley from the University of Manchester analysed 51 fossilised marsupial bones found in caves and swamps in Tasmania, one of the last refuges of Australia's giant fauna. Using the advanced technique of zooarchaeology by mass spectrometry (ZooMS), or "collagen fingerprinting", the researchers were able to study samples more than 100,000 years old - that is, much older than the limit at which analysable DNA can usually be extracted.

According to Buckley, Australia's hot climate destroys ancient DNA, which is why it has long been difficult to establish precise evolutionary links between extinct and modern species. Collagen, the protein that makes up bone tissue, among other things, is much more resilient. Its fragments are preserved in highly fragmented and very old bones, allowing not only to determine species affiliation, but also to restore kinship between extinct and living today's marsupials.

The most unexpected result was the discovery of a close relationship between the koala and the so-called marsupial lion, one of the largest predatory mammals ever to inhabit Australia. Collagen analysis showed that these two very different looking animals shared a common ancestor some 25-35 million years ago. This brings their evolutionary lineages much closer together than previously thought.

The work also provided new biomolecular data on two other extinct species, Zygomaturus trilobus and Palorchestes azael. Comparison of their collagen sequences confirmed that both belong to the broader family of wombats and koalas, Vombatiformes.

The results are important not only for clarifying the family tree, but also for understanding one of the biggest mysteries of Australian prehistory - the extinction of continental megafauna. In the late Pleistocene, Australia lost almost 90 per cent of its large land animals. Scientists are still debating whether climate change, the arrival of humans or a combination of both played a decisive role.

ZooMS technology makes it possible to determine the species affiliation of even tiny bone fragments that previously could not be assigned to any species. This helps to clarify the timing of megafauna extinction and the periods of its coexistence with humans.

"ZooMS makes it possible to rapidly analyse thousands of fossil specimens," Buckley notes. - This could be a breakthrough in the study of extinct species: we can more accurately identify finds, improve the chronology of extinctions and better understand ancient biodiversity".