Sloths

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

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

Not Living up to their Name
Max Planck scientists find evidence that sloths in the wild sleep a lot less than previously thought. [PDF]
http://www.orn.mpg.de/aktuelles/presse/faultier_en.pdf

Pale-throated Three-toed Sloth: Bradypus tridactylus
Research project by Joe Thomas on this tree-living mammal including its classification, habitat, reproduction, adaptations, nutrition and interactions with other species.
http://bioweb.uwlax.edu/bio203/s2008/thomas_joe/

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