Sloths

Family: Bradypodidae - General information and anatomy of the three toed sloth.
animaldiversity.ummz.umich.edu/chordata/mammalia/xenarthra/bradypodidae.html

Family: Megalonychidae - General information and anatomy of the two toed sloth.
animaldiversity.ummz.umich.edu/chordata/mammalia/xenarthra/megalonychidae.html

Three-toed Sloth - Information from Wikipedia on the four sloths included in the Bradypodidae family.
en.wikipedia.org/wiki/Bradypodidae

Two-toed Sloth - Information from Wikipedia on the classification of the family Megalonychidae which contains just two species, Choloepus didactylus and Choloepus hoffmanni.
en.wikipedia.org/wiki/Megalonychidae