14 DAY TRIAL // In a series of new genetic investigations, experts demonstrate that kangaroos and other marsupials did not evolve in Antarctica, as previously thought. It would appear that the animals actually appeared in South America, and that they still exist there today. Marsupials stand out from other species through the fact that they feed and carry their youngsters around in special pouches on their bellies. With the new finding, experts are bound to gather even more data on the history of this family of creatures.
In order to make the research possible, scientists looked at the marsupial species that still live in South America today. “The two recently sequenced marsupial genomes of the South American opossum (Monodelphis domestica) and a kangaroo, the Australian tammar wallaby (Macropus eugenii), provide a unique opportunity to apply a completely new approach to resolve marsupial relationships,” explains researcher Maria A. Nilsson. She is based at the University of Munster, in Germany, LiveScience reports.
Nilsson is also the leader of an international group of experts that conducted the new investigation. The group published its findings in the July 27 issue of the esteemed open-access journal PLoS Biology, which is edited by the Public Library of Science. The group reveals that studies highlight a very interesting point – all marsupials living today, in both South American and Australia – share a common ancestor. The conclusion was derived from analysis of special genetic markers called retroposons, which are identical in marsupials on both continents.
However, determining the history of this animal group for a fact is very difficult, given that no hard evidence exist. Researchers would be ecstatic to find a fossil of an intermediary creature, but thus far such a finding has eluded them. The genetic data seems to indicate that the species currently in existence – as well as some that have since gone extinct – separate from a common ancestor around 80 million years ago. At that time, the landmass that contained Antarctica, Australia and South America broke apart, and the three new continents began drifting on Earth's mantle.