Giant sloths, slow moving creatures from the last full ice age that weighed three tons, were wiped out by hunting, not climate changes, according to a study from the University of Florida.
UF professor David Steadman analyzed fossils from Cuba and Hispaniola, the nearby island that houses the Dominican Republic and Haiti, and found that the last fossils for the shaggy beasts were about 4400 years old. That's far earlier than the end of the last ice age--11,000 years ago--but it coincides with the arrival of humans on the two islands.
"If climate were the major factor driving the extinction of ground sloths, you would expect the extinctions to occur at about the same time on both the islands and the continent since climate change is a global event," Steadman said in a prepared statement.
Steadman said the results didn't surprise him. Climate change is slow and often species, though breeding and natural selection, will adapt to it. New predators move much more quickly. The reason the living species of sloths survive is that they live high up in trees, where their green-algae-colored fur camouflages them
More than three-fourths of the large species of mammals that roamed North American became extinct within a few thousand years, which, besides ground sloths, included mammoths, mastodons, saber-toothed tigers and giant bears, Steadman