1. All sloths have three toes on each of their hind legs. Two-toed sloths and three-toed sloths differ in the number of fingers on their front limbs.

2. Until 10,000 years ago, South America had a big population of giant sloths the size of elephants.

3. The giant sloth Megalonyx jeffersonii is named after Thomas Jefferson, who delivered a paper on his study of its fossil bones in 1797.

4. Jefferson thus became the only US President to have a sloth named after him.