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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: High Temperatures Turn Mammals Into Dwarves
7 November 2013 2:30 pm
LOS ANGELES, CALIFORNIA—When Earth warms, mammals shrink. That’s what researchers found when they looked back 56 million years, during a time when global temperatures increased about 6° for a period of 20,000 years. Early horses, for example the now-extinct Hyracotherium (shown on the right next to a modern horse on the left), shrunk by about 30%, presumably to increase the ratio of skin area to body volume, and thus lose heat more easily. Now, scientists have found that this wasn’t a one-off event. At last week’s meeting here of the Society of Vertebrate Paleontology, another team of U.S.-based researchers looked at a slightly later but somewhat less severe warming period, which happened about 53 million years ago. Using molar size as a proxy for body size, the researchers looked at mammals in sediments from the fossil-rich Bighorn Basin of Wyoming. They found that the same thing happened: Mammals, including deer and small primates that resembled today’s lemurs, got small again, with horses like Hyracotherium downsizing by about 22% this time. In both cases, the animals rebounded to their previous sizes when the warming episode was over. Both this and the earlier warming episode were preceded by big increases in atmospheric carbon dioxide, similar to what we are seeing today. Time to get small, everyone?