| Kingdom Animalia Subclass Theria Superorder Xenarthra Scientific name Mylodontidae Rank Family | Phylum Chordata Infraclass Eutheria Order Pilosa Higher classification Sloth | |
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| Similar Megatheriidae, Xenarthra, Sloth, Mammal, Glossotherium | ||
Mylodontidae is a family of extinct mammals within the order of Pilosa and suborder Folivora living from approximately 23 mya—11,000 years ago, existing for approximately 22.89 million years. This family of ground sloths is related to the other families of extinct ground sloths, Megatheriidae and Nothrotheriidae. The only extant families of the suborder Folivora are Bradypodidae and Megalonychidae (the latter has extinct terrestrial species as well as extant arboreal species). Phylogenetic analyses using homologous sequences from all extant edentate groups indicates that Mylodontidae was more closely related to Megalonychidae than to Bradypodidae.
The mylodontids together with their relatives form Mylodonta, the second radiation of ground sloths. 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. However, radiocarbon dates do not support simultaneous occupation of the site by humans and sloths. Subfossil remains like coproliths, fur and skin have been discovered in some quantities.