As climate warmed, early horses shrank
Past climate warming resulted in tiny horses, a finding that suggests mammals shrink when temperatures rise.
In a study appearing in the journal Science, researchers led by scientists from the University of Florida and the 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.
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.
Full story at Futurity.
Photo credit: Kristen Grace
