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Mylodontidae; Temporal range: Late Oligocene-Early Holocene (Hemphillian-Rancholabrean) (NALMA) &(Deseadan-Lujanian) (SALMA) ; ~29–0.010 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Paramylodon harlani at the Texas Memorial Museum, UT
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Pilosa
Superfamily:	Mylodontoidea
Family:	†Mylodontidae; Ameghino, 1889
Subgroups
	†Baraguatherium; †Eionaletherium; †Octodontotherium; †Octomylodon; †Orophodon; †Paroctodontotherium; †Pseudoprepotherium; †Urumacotherium; †Scelidotheriinae?; †Mylodontinae;

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.^[2] This family is most closely related to another family of extinct ground sloths, Scelidotheriidae, as well as to the extant arboreal two-toed sloths, family Choloepodidae; together these make up the superfamily Mylodontoidea. 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.^[3] However, molecular sequence comparisons were needed for the correct placement of Choloepodidae. These studies have been carried out using mitochondrial DNA sequences^[4]^[5] as well as with collagen amino acid sequences.^[6] The latter results indicate that Choloepodidae is closer to Mylodontidae than Scelidotheriidae is. The only other living sloth family, Bradypodidae (three-toed sloths), belongs to a different sloth radiation, Megatherioidea.^[5]^[6]

The mylodontoids form one of three major radiations of 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.^[7] However, radiocarbon dates do not support simultaneous occupation of the site by humans and sloths.^[8] Subfossil remains like coproliths, fur and skin have been discovered in some quantities. Mylodontids are the only ground sloths confirmed to have osteoderms embedded within their skin, though osteoderms were only present in a handful of genera (Mylodon, Paramylodon and Glossotherium) and absent in others.^[9]

Phylogeny

The following sloth family phylogenetic tree is based on collagen and mitochondrial DNA sequence data (see Fig. 4 of Presslee et al., 2019).^[6]

Folivora

† Megalocnidae (Caribbean sloths)

Mylodontoidea

† Scelidotheriidae

	† Scelidodon sp.

	† Scelidotherium sp.

† Mylodontidae

† Lestodon armatus

† Paramylodon harlani

	† Glossotherium robustus

	† Mylodon darwinii

Choloepodidae
(two-toed sloths)

	Choloepus didactylus

	Choloepus hoffmanni

Megatherioidea

	† Megalonychidae

	Bradypodidae (three-toed sloths)

	† Nothrotheriidae

	† Megatheriidae

References

^ Rincón, Ascanio D.; Solórzano, Andrés; McDonald, H. Gregory; Flores, Mónica Núñez (7 April 2016). "Baraguatherium takumara, Gen. et Sp. Nov., the Earliest Mylodontoid Sloth (Early Miocene) from Northern South America". Journal of Mammalian Evolution. 24 (2): 179–191. doi:10.1007/s10914-016-9328-y. S2CID 23667414.
^ Paleobiology Database Paleobiology Database [1]
^ Gaudin, T. J. (1995-09-14). "The Ear Region of Edentates and the Phylogeny of the Tardigrada (Mammalia, Xenarthra)". Journal of Vertebrate Paleontology. 15 (3): 672–705. Bibcode:1995JVPal..15..672G. doi:10.1080/02724634.1995.10011255. JSTOR 4523658.
^ Hoss, Matthias; Dilling, Amrei; Currant, Andrew; Paabo, Svante (9 Jan 1996). "Molecular phylogeny of the extinct ground sloth Mylodon darwinii". Proceedings of the National Academy of Sciences. 93 (1): 181–185. Bibcode:1996PNAS...93..181H. doi:10.1073/pnas.93.1.181. PMC 40202. PMID 8552600.
^ ^a ^b Delsuc, F.; Kuch, M.; Gibb, G. C.; Karpinski, E.; Hackenberger, D.; Szpak, P.; Martínez, J. G.; Mead, J. I.; McDonald, H. G.; MacPhee, R.D.E.; Billet, G.; Hautier, L.; Poinar, H. N. (2019). "Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths". Current Biology. 29 (12): 2031–2042.e6. Bibcode:2019CBio...29E2031D. doi:10.1016/j.cub.2019.05.043. hdl:11336/136908. PMID 31178321.
^ ^a ^b ^c Presslee, S.; Slater, G. J.; Pujos, F.; Forasiepi, A. M.; Fischer, R.; Molloy, K.; et al. (2019). "Palaeoproteomics resolves sloth relationships" (PDF). Nature Ecology & Evolution. 3 (7): 1121–1130. Bibcode:2019NatEE...3.1121P. doi:10.1038/s41559-019-0909-z. PMID 31171860. S2CID 174813630. Archived (PDF) from the original on 12 September 2020. Retrieved 18 September 2020.
^ Woodward (1900)
^ Naish, Darren (28 Nov 2005). "Fossils explained 51: Sloths". Geology Today. 21 (6): 232–238. doi:10.1111/j.1365-2451.2005.00538.x. S2CID 85808869. Retrieved 2009-01-29.
^ McDonald, H. Gregory (December 2018). "An Overview of the Presence of Osteoderms in Sloths: Implications for Osteoderms as a Plesiomorphic Character of the Xenarthra". Journal of Mammalian Evolution. 25 (4): 485–493. doi:10.1007/s10914-017-9415-8. ISSN 1064-7554. S2CID 254697023.

Bibliography

Woodward, A.S. (1900): On some remains of Grypotherium (Neomylodon) listai and associated mammals from a cavern near Consuelo Cove, Last Hope Inlet. Proceedings of the Zoological Society of London, 1900(5): 64–79.