Mylodontidae is a family of extinct South American and North American
ground sloth
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...
s within the suborder
Folivora
Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their l ...
of order
Pilosa
The order Pilosa is a clade of xenarthran placental mammals, native to the Americas. It includes the anteaters and sloths (which includes the extinct ground sloths). The name comes from the Latin word for "hairy".
Origins and taxonomy
The b ...
, living from around 23 million years ago (Mya) to 11,000 years ago. This family is most closely related to another family of extinct ground sloths,
Scelidotheriidae
Scelidotheriidae is a family of extinct ground sloths within the order Pilosa, suborder Folivora and superfamily Mylodontoidea, related to the other extinct mylodontoid family, Mylodontidae, as well as to the living two-toed sloth family Choloe ...
, as well as to the extant
arboreal
Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...
two-toed sloths, family
Choloepodidae; together these make up the superfamily
Mylodontoidea
Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their li ...
.
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analyses based on morphology uncovered the relationship between Mylodontidae and Scelidotheriidae; in fact, the latter was for a time considered a subfamily of mylodontids.
However, molecular sequence comparisons were needed for the correct placement of Choloepodidae. These studies have been carried out using
mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
sequences
as well as with
collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...
amino acid sequences.
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
Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their li ...
.
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
corral
A pen is an enclosure for holding livestock. It may also perhaps be used as a term for an enclosure for other animals such as pets that are unwanted inside the house. The term describes types of enclosures that may confine one or many animal ...
s when they could procure a young ground sloth, to raise the animal to butchering size.
[Woodward (1900)] However,
radiocarbon dates do not support simultaneous occupation of the site by humans and sloths.
Subfossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
remains like coproliths, fur and skin have been discovered in some quantities.
Phylogeny
The following sloth family phylogenetic tree is based on collagen and mitochondrial DNA sequence data (see Fig. 4 of Presslee ''et al''., 2019).
References
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
*
*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.
* (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
* (1980): ''Pleistocene Mammals of North America.'' Columbia University Press, New York.
*McKenna, Malcolm C. & Bell, Susan K. (1997): ''Classification of Mammals Above the Species Level.'' Columbia University Press, New York.
*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.
*
External links
* Sloth World: An Online Sloth Bibliography
*
ttps://web.archive.org/web/20060823122149/http://www.acnatsci.org/museum/leidy/paleo/megalonyx.html Academy of Natural Sciences ground sloth pageIllinois State Museum ground sloth page''Eremotherium'' in FloridaWestern Center for Archaeology and PaleontologyHemet, CA
{{Taxonbar, from=Q1749282
Neogene mammals of South America
Quaternary mammals of South America
Rupelian first appearances
Holocene extinctions
Prehistoric mammal families
Taxa named by Florentino Ameghino