Killer Sloth

The lethargic two-foot-long tree-hugging sloths of the South and Central American tropics are small fry compared with one of their extinct relatives. Megatherium americanum, a ground sloth, stood 12 feet tall, had 7-inch claws, and weighed close to 9,000 pounds. It roamed the arid steppes of southern South America about a million years ago. And it may have been the largest hunting mammal ever to walk the Earth.