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Tuesday, October 7, 2008

Photo: "Global Cooling" Wiped Out North America's Reptiles, Amphibians, Study Finds


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Rock formations at Toadstool Geological Park in Nebraska show an abrupt transition in North America's climate some 34 million years ago. Layers of sediment from an earlier, warmer period appear below and to the left, and layers from a cooler, more recent period are above and to the right.

A new study shows that a period of global cooling, likely caused by a sudden plunge in levels of carbon dioxide, led to the extinction of many of North America's reptiles and amphibians.

Photograph courtesy Matt Kohn/Nature