Add Yahoo as a preferred source to see more of our stories on Google. Harlan's ground sloth fossil skeleton excavated and displayed at the La Brea Tar Pits in Los Angeles. Larisa DeSantis A two-toed ...

Imagine a sloth. You probably picture a medium-sized, tree-dwelling creature hanging from a branch. Today's sloths—commonly featured on children's backpacks, stationery and lunch boxes—are slow-moving ...