Giant ground sloths are known for having had incredibly large claws. Tree-dwelling sloths weighed in at about 14 pounds, compared to 174 pounds for the ground sloths. Branches break when there is too much weight on them and tree sloths have reportedly survived 100 foot falls. What is less obvious to paleontologists is why ground sloths grew to such enormous sizes in the first place. Some ground sloths also had little pebble-like osteoderms embedded in their skin,” Narducci said, in reference to the bony plating that sloths had in common with their armadillo relatives.