This is a video about koalas.
From the University of Queensland in Australia:
Koalas not descended from giants
Friday, 12 December 2008
University of Queensland (UQ) research has found one of Australia’s iconic animals is not a shadow of its former self.
Palaeontologist Dr Gilbert Price, from UQ’s Centre for Microscopy & Microanalysis, said there was a long-held view modern koalas were a dwarf version of a giant koala that lived between 30 000 and 700 000 years ago.
But Dr Price said his research into the fossil record of koalas didn’t support that theory and modern koalas can stand tall in the knowledge they are their own separate species.
“By looking at the fossil record of both types of koalas, I found that they existed together for hundreds of thousands of years through prehistory,” Dr Price said.
“This contrasts with the previous idea that the modern koala originated only after the loss of the giant koala, following the megafauna extinction event some 30 to 50 000 years ago.
“Also there are distinct differences in the appearance of both forms, other than simply size. Together these results suggest the two forms are distinct species and the modern koala is not a dwarf descendent of the giant koala.”
Dr Price said the two species would have even lived in the same areas at the same time, which would have made an interesting sight.
“On the one hand we have a 20-30kg giant koala, the largest tree-dwelling marsupial ever to have lived,” he said.
“And then we have the modern koala weighing in at 10kg, so there would have been quite a contrast.”
But he said study left some unanswered questions about the evolution of the koala how it had adapted to life in Australia over hundreds of thousands of years.
“The results beg the question, where on earth did the modern koala come from?” he said.
“A lack of well-dated fossil records means determining the true ancestor of the modern koala is most difficult.”
“Another question is, what is it about the little guy that allowed it to persist through such intense periods of environmental changes and survive until today, when the big fella decided to drop out over 50 000 years ago?”
“It’s absolutely critical that we can find the answers to such questions, and that we find them soon as it’ll go a long way in the planning of management strategies to conserve the modern koala well into the future.”
Dr Price’s research has recently been published in the journal Quaternary Science Reviews.
See also here.
Maybe the giant koala lived in bigger trees, the only ones able to carry his weight, than the smaller species. The drying of the climate may have meant fewer big trees: a problem for the bigger species, not such a problem for the smaller one.
Endangered numbat population gets a boost in Western Australia: here.
Earliest South American paucituberculatans and their significance in the understanding of ‘pseudodiprotodont’ marsupial radiations: here.