NEW MEXICO: Fossilized footprints from a dry lake bed in White Sands National Monument divulge an extraordinary interaction between humans and a ground sloth 10,000 to 15,000 years ago. Human tracks superimposed on the prints of the giant sloth show how people carefully stalked the beast. The sloth’s trail suggests it then employed a series of evasive maneuvers and even reared up on its hind legs, likely to defend itself. It is not known exactly why giant sloths went extinct, but human hunting may have contributed to their demise.