Class: Mammalia (Linnaeus, 1758) – mammals
Order: Pilosa (Flower, 1883) - a group of placental mammals found in the Americas, including anteaters and sloths, and extinct ground sloths
Family: Megalonychidae (Ameghino, 1889) – two-toed sloths
Genus: Choloepus (Illiger, 1811) – two-toed sloths
Species: Choloepus didactylus (Linnaeus, 1758) – southern two-toed sloth, Linnaeus's two-toed sloth, Linné's two-toed sloth
Species: Choloepus hoffmanni (Peters, 1858) – Hoffmann's two-toed sloth
Illustration of a two-toed sloth from a 1900 school textbook.
From Introduction to zoology; a guide to the study of animals, for the use of secondary schools (1900); p.343.
Image credit: Made available on Flickr by Internet Archive Book Images. No known copyright restrictions.
Anderson and Hanley (2001)
Barros et al. (2008)
Gaudin and McDonald (2008)
Wilson & Reeder (2005)