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Earliest horses show past global warming affected body size of mammals
http://news.ufl.edu/2012/02/23/earliest-horses/[font face=Times, Times New Roman, Serif][font size=5]Earliest horses show past global warming affected body size of mammals[/font]
Thursday, February 23, 2012
[font size=3]GAINESVILLE, Fla. — As scientists continue developing climate change projection models, paleontologists studying an extreme short-term global warming event have discovered direct evidence about how mammals respond to rising temperatures.
In a study appearing in Science Feb. 24, researchers from eight institutions led by scientists from the University of Florida and University of Nebraska found a correlation between temperature and body size in mammals by following the evolution of the earliest horses about 56 million years ago: As temperatures increased, their body size decreased.
“Horses started out small, about the size of a small dog like a miniature schnauzer,” said co-author Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History on the UF campus. “What’s surprising is that after they first appeared, they then became even smaller and then dramatically increased in size, and that exactly corresponds to the global warming event, followed by cooling. It had been known that mammals were small during that time and that it was warm, but we hadn’t understood that temperature specifically was driving the evolution of body size.”
Sifrhippus, the earliest-known horse, first appeared in the North American fossil record during the Paleocene-Eocene Thermal Maximum. During this 175,000-year climate event, increased concentrations of carbon dioxide in the atmosphere and oceans caused average global temperatures to rise 10 to 20 degrees. By analyzing the size and isotopes of fossils collected in Wyoming’s Bighorn Basin, researchers traced the evolution of Sifrhippus from an estimated 12-pound animal that shrank during a 130,000-year period about 30 percent to 8.5 pounds — the size of a small house cat — then increased to about 15 pounds during the next 45,000 years.
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http://dx.doi.org/10.1126/science.1213859Thursday, February 23, 2012
[font size=3]GAINESVILLE, Fla. — As scientists continue developing climate change projection models, paleontologists studying an extreme short-term global warming event have discovered direct evidence about how mammals respond to rising temperatures.
In a study appearing in Science Feb. 24, researchers from eight institutions led by scientists from the University of Florida and University of Nebraska found a correlation between temperature and body size in mammals by following the evolution of the earliest horses about 56 million years ago: As temperatures increased, their body size decreased.
“Horses started out small, about the size of a small dog like a miniature schnauzer,” said co-author Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History on the UF campus. “What’s surprising is that after they first appeared, they then became even smaller and then dramatically increased in size, and that exactly corresponds to the global warming event, followed by cooling. It had been known that mammals were small during that time and that it was warm, but we hadn’t understood that temperature specifically was driving the evolution of body size.”
Sifrhippus, the earliest-known horse, first appeared in the North American fossil record during the Paleocene-Eocene Thermal Maximum. During this 175,000-year climate event, increased concentrations of carbon dioxide in the atmosphere and oceans caused average global temperatures to rise 10 to 20 degrees. By analyzing the size and isotopes of fossils collected in Wyoming’s Bighorn Basin, researchers traced the evolution of Sifrhippus from an estimated 12-pound animal that shrank during a 130,000-year period about 30 percent to 8.5 pounds — the size of a small house cat — then increased to about 15 pounds during the next 45,000 years.
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