Our adult had a problem–its tail was wounded in some kind of incident and
Two fused caudal vertebrae (left) with normal vertebra (right)
two adjacent vertebrae fused as the wound healed making movement in the joint impossible. Did another animal step on it accidentally? Was it wounded by a predator? Injured in a fight with another sloth? There’s no way of knowing. If sloths used their tails like the third leg of a stool, i.e. to lean back on when they stood up, as some scientists suggest, our sloth was probably in pain every time she did. Ground sloths used their tails in different ways–in Peru they flapped them while they swam grazing on seaweed on the bottom of the ocean. (Muizon and McDonald, 1995)