Mammal size maxed out after dinos' demise

Opening new ecological niches led to worldwide boom in size

By Susan Milius, 17:15 PM November 24, 2010

After dinosaurs went extinct 65 million years ago, land mammals tended to supersize and then hit a limit, roughly at the same time worldwide.

“Globally, there is a really clean pattern that shows up,” says paleoecologist Felisa A. Smith of the University of New Mexico in Albuquerque. In the broadest survey yet of big-mammal body size, she and colleagues found that mammal groups around the world tended to give rise to giant species at about the same time. The largest, for example, the hornle...

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