Mylodontidae

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]

Mylodontidae
Paramylodon harlani at the Texas Memorial Museum, UT
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pilosa
Superfamily: Mylodontoidea
Family: †Mylodontidae
Ameghino, 1889
Subgroups

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)

Nothrotheriidae

Megatheriidae

Megalonychidae

Bradypodidae (three-toed sloths)
Megatherioidea

  Scelidotheriidae  

Scelidotherium sp.

Scelidodon sp.

Choloepodidae
  (two-toed sloths)  

C. didactylus

C. hoffmanni

  Mylodontidae  

Lestodon armatus

Paramylodon harlani

Mylodon darwinii

Glossotherium robustus    
Mylodontoidea

References
  1. 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.
  2. http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=43629&is_real_user=1Mylodontidae: Paleobiology Database Archived 2012-10-13 at the Wayback Machine
  3. 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.
  4. 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.
  5. 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. doi:10.1016/j.cub.2019.05.043. PMID 31178321.
  6. Presslee, S.; Slater, G. J.; Pujos, F.; Forasiepi, A. M.; Fischer, R.; Molloy, K.; Mackie, M.; Olsen, J. V.; Kramarz, A.; Taglioretti, M.; Scaglia, F.; Lezcano, M.; Lanata, J. L.; Southon, J.; Feranec, R.; Bloch, J.; Hajduk, A.; Martin, F. M.; Gismondi, R. S.; Reguero, M.; de Muizon, C.; Greenwood, A.; Chait, B. T.; Penkman, K.; Collins, M.; MacPhee, R.D.E. (2019). "Palaeoproteomics resolves sloth relationships" (PDF). Nature Ecology & Evolution. 3 (7): 1121–1130. doi:10.1038/s41559-019-0909-z. PMID 31171860. S2CID 174813630.
  7. Woodward (1900)
  8. 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.
  9. 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.
Mylodontidae fossils at La Plata Museum, Argentina.

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.

Further reading
  • Brandoni, Diego; Scillato Yané, Gustavo J.; Miño Boilini, Ángel R.; Favotti, Emmanuel (2016). "Los Tardigrada (Mammalia, Xenarthra) de Argentina: diversidad, evolución y biogeografía" (PDF). Contribuciones del MACN. _: 263–274. Retrieved 2018-10-08.
  • Cuvier, G. (1796): Notice sur le squellette d'une très grande espèce de quadrupède inconnue jusqu'à présent, trouvé au Paraquay, et déposé au cabinet d'histoire naturelle de Madrid. Magasin encyopédique, ou Journal des Sciences, des Lettres et des Arts (1): 303-310; (2): 227-228.
  • De Iuliis, G. & Cartelle, C. (1999): A new giant megatheriine ground sloth (Mammalia: Xenarthra: Megatheriidae) from the late Blancan to early Irvingtonian of Florida. Zool. J. Linn. Soc. 127(4): 495-515.
  • Harrington, C.R. (1993): Yukon Beringia Interpretive Center - Jefferson's Ground Sloth. Retrieved 2008-JAN-24.
  • Hogan, C.M. (2008): Cueva del Milodon, Megalithic Portal. Retrieved 2008-APR-13
  • Kurtén, Björn and Anderson, Elaine (1980): Pleistocene Mammals of North America. Columbia University Press, New York. ISBN 0-231-03733-3
  • McKenna, Malcolm C. & Bell, Susan K. (1997): Classification of Mammals Above the Species Level. Columbia University Press, New York. ISBN 0-231-11013-8
  • Nowak, R.M. (1999): Walker's Mammals of the World (Vol. 2). Johns Hopkins University Press, London.
  • White, J.L. (1993): Indicators of locomotor habits in Xenarthrans: Evidence for locomotor heterogeneity among fossil sloths. Journal of Vertebrate Paleontology, 13(2): 230-242.
  • White, J.L.; MacPhee, R.D.E. (2001). "The sloths of the West Indies: a systematic and phylogenetic review". In Woods, C.A.; Sergile, F.E. (eds.). Biogeography of the West Indies: Patterns and Perspectives. Boca Raton, London, New York, and Washington, D.C.: CRC Press. pp. 201–235. doi:10.1201/9781420039481-14. ISBN 978-0-8493-2001-9.
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