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Hot, Hotter, Hot: Climate seesawed during dinosaur age

Dinosaurs, too, endured climate change. Although scientists had speculated that the world some 120 million years ago was unvaryingly hot, climate fluctuated dramatically, a new report argues. Twice during a 250,000-year period in the reign of the dinosaurs, tropical sea-surface temperatures varied by 6°C, the findings suggest. That's twice as much variability as is known to have occurred at any other time in history.

"Since animals evolved on Earth, this range of temperature shift is unprecedented," says Simon C. Brassell of Indiana University in Bloomington, an author of the report, which appears in the October Geology. To determine the ancient temperatures, Brassell and his colleagues used a new method that measures the composition of the cell membranes of a marine microbe that accumulated on the ocean floor.

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