Thursday, April 3, 2008

Shedding Light on the Evolution of Marsupials

The discovery of fossil fragments of Djarthia, the earliest known Australian marsupial. and a subsequent study has helped to shed light on the evolutionary history of marsupials, in particular, Dromiciops gliroides (Monito del Monte), a South American species.

Marsupials are generally thought to have originated in South America and spread into Australia via the Antarctic continent, during a period when the three continents were connected. However, Monito del Monte appears to be most directly descended from Djarthia. It would seem that Monito del Monte evolved from a line of Australian marsupials who migrated back to South America. before the supercontinent (Gondwana) broke up around 40 million years ago.

This new study was made possible by the discovery of the new fossil fragments of Djarthia, known only by teeth previously. The ankle and ear bones recovered in Australia allowed for a more complete comparison to be made between Djarthia and Monito del Monte. The study of the fossils was conducted by Mr. Robin Beck.

Get the extended story at ScienceDaily:

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