The delayed rise of present-d...( quire further study. Modern mamma...)

"Modern mammals went though an early period of diversification about 93 million years ago, when the major groups - the superorders and orders - appeared, but after that the rate dropped and stayed fairly low for the next 40 million years. It was other groups of mammals, not those we see today, that took advantage of the extinction of the dinosaurs,' says Mr Beck.

The research, which appears in the March 29 issue of the journal Nature and was led by Olaf R.P. Bininda-Emonds of the Technical University of Munich and Andy Purvis of Imperial College in London, brought together a diverse group of scientists to produce the first comprehensive analysis of mammalian biodiversity from about 160 million years ago to the present day.

The team included contributors came from the Zoological Society of London, American Museum of Natural History, the Royal Botanic Gardens, the National Evolutionary Synthesis Center, the University of British Columbia and the University of Georgia.

Many paleontologists believed the mass extinction of dinosaurs allowed the ancestors of modern mammals to flourish and begin the long evolutionary process culminating in the diverse array of species we see today.

"For many years, molecular biologists and paleontologists shared different views about the rise of present-day mammals," said a team member, Ross MacPhee, a curator in the Division of Vertebrate Zoology at the American Museum of Natural History.

"Extensive molecular data indicate that our common mammalian roots have to go back 90 to 100 million years, if not more, but many paleontologists have been dubious of this claim given the lack of ancestral-looking fossils until about 50 to 55 million years ago. This new work helps reconcile those differences. Now we know the ancestors of living mammal groups were there, but in very low numbers."

Supertrees are a kind of summary of evolutionary history for a larg
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Contact: Robin Beck
robin.beck@student.unsw.edu.au
61-403-280-788
University of New South Wales
28-Mar-2007