Mylodontidae is a family of extinct South American and North American ground sloths within the suborder Folivora of order Pilosa, living from around 23 million years ago (Mya) to 11,000 years ago.

Phylogenetic analyses based on morphology uncovered the relationship between Mylodontidae and Scelidotheriidae; in fact, the latter was for a time considered a subfamily of mylodontids.

The discovery of their fossils in caverns associated with human occupation lead some early researchers to theorize that the early humans built corrals when they could procure a young ground sloth, to raise the animal to butchering size.

[7] However, radiocarbon dates do not support simultaneous occupation of the site by humans and sloths.

[9] The following sloth family phylogenetic tree is based on collagen and mitochondrial DNA sequence data (see Fig.