American Museum of Natural History mounts of (from left) Megalocnus rodens, Scelidotherium cuvieri, Megalonyx wheatleyi, Glossotherium robustus
Scientific classification
Domain:
Eukaryota
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Pilosa
Suborder:
Folivora
Families
†Megalocnidae (in part)
†Megalonychidae
†Megatheriidae
†Nothrotheriidae
†Mylodontidae
†Scelidotheriidae
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. Ground sloths varied widely in size, with the largest, belonging to genera Megatherium and Eremotherium, being around the size of elephants. Ground sloths are a paraphyletic group, as living tree sloths are thought to have evolved from ground sloth ancestors.
The early evolution of ground sloths took place during the late Paleogene and Neogene of South America, while the continent was isolated. At their earliest appearance in the fossil record, the ground sloths were already distinct at the family level. Sloths dispersed into the Greater Antilles during the Oligocene, and the presence of intervening islands between the American continents in the Miocene allowed a dispersal of some species into North America, They were hardy as evidenced by their high species diversity and their presence in a wide variety of environments, extending from the far south of Patagonia (Cueva del Milodón Natural Monument) to Alaska.[1][2][3] Sloths, and xenarthrans as a whole, represent one of the more successful South American groups during the Great American Interchange after the connection of North and South America during the late Pliocene with a number of ground sloth genera migrating northwards. One genus, Thalassocnus, even adapted for marine life along the Pacific coast of South America during the late Miocene and Pliocene epochs.
Ground sloths, which were represented by over 30 living species during the Late Pleistocene, abruptly became extinct on the American mainland as part of the Late Pleistocene extinctions at the end of the Pleistocene, around 12,000 years ago simultaneously along with most other large mammals in the Americas. Their extinction has been posited to be the result of hunting by recently arrived humans and/or climate change.[4][5] A number of kill sites are known where humans butchered ground sloths dating just prior to their extinction.
The Caribbean ground sloths, the most recent survivors, lived in the Antilles, possibly until 1550 BCE. However, radiocarbon dating suggests an age of between 2819 and 2660 BCE for the last occurrence of Megalocnus in Cuba.[6] They survived 5,000–6,000 years longer in the Caribbean than on the American mainland, which correlates with the later colonization of this area by humans.[7]
^C.M. Hogan (2008)
^Stock, Chester (1942-05-29). "A Ground Sloth in Alaska". Science. 95 (2474): 552–553. Bibcode:1942Sci....95..552S. doi:10.1126/science.95.2474.552. ISSN 0036-8075. PMID 17790868.
^McDonald, H.G.; Harington, C.R.; De Iuliis, G. (2000-01-01). "The Ground Sloth, Megalonyx, from Pleistocene Deposits of the Old Crow Basin, Yukon, Canada". Arctic. 53 (3). doi:10.14430/arctic852. ISSN 1923-1245.
^Fiedal, Stuart (2009). "Sudden deaths: The chronology of terminal Pleistocene megafaunal extinction". In Haynes, Gary (ed.). American Megafaunal Extinctions at the End of the Pleistocene. Vertebrate Paleobiology and Paleoanthropology. Springer. pp. 21–37. doi:10.1007/978-1-4020-8793-6_2. ISBN 978-1-4020-8792-9.
^MacPhee, R.D.E.; Iturralde-Vinent, M.A.; Vázquez, O.J. (June 2007). "Prehistoric Sloth Extinctions in Cuba: Implications of a New 'Last' Appearance Date". Caribbean Journal of Science. 43 (1). College of Arts and Sciences, University of Puerto Rico: 94–98. doi:10.18475/cjos.v43i1.a9. S2CID 56003217. Retrieved 11 May 2009.
^Steadman, D.W.; Martin, P.S.; MacPhee, R.D.E.; Jull, A.J.T.; McDonald, H.G.; Woods, C.A.; Iturralde-Vinent, M.; Hodgins, G.W.L. (2005-08-16). "Asynchronous extinction of late Quaternary sloths on continents and islands". Proceedings of the National Academy of Sciences. 102 (33). United States National Academy of Sciences: 11763–11768. Bibcode:2005PNAS..10211763S. doi:10.1073/pnas.0502777102. PMC 1187974. PMID 16085711.
Groundsloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. Groundsloths varied widely in size, with the largest, belonging...
arboreal tree sloths and extinct terrestrial groundsloths. Noted for their slowness of movement, tree sloths spend most of their lives hanging upside down...
méga (μέγα) 'great' + theríon (θηρίον) 'beast') is an extinct genus of groundsloths endemic to South America that lived from the Early Pliocene through...
Megalonyx (Greek, "great-claw") is an extinct genus of groundsloths of the family Megalonychidae, native to North America. It evolved during the Pliocene...
The sloth bear (Melursus ursinus), also known as the Indian bear, is a myrmecophagous bear species native to the Indian subcontinent. It feeds on fruits...
Mylodontidae is a family of extinct South American and North American groundsloths within the suborder Folivora of order Pilosa, living from around 23...
Nothrotheriops is a genus of Pleistocene groundsloth found in North America, from what is now central Mexico to the southern United States. This genus...
"steppe or desert" and θηρίον "beast") is an extinct genus of giant groundsloth in the family Megatheriidae. Eremotherium lived in southern North America...
creators combined the traits of three-toed sloths and groundsloths while designing Sid and the other sloth characters. Paleontologists have suggested...
Paramylodon is an extinct genus of groundsloth of the family Mylodontidae endemic to North America during the Pliocene through Pleistocene epochs, living...
Megatheriidae is a family of extinct groundsloths that lived from approximately 23 mya—11,000 years ago. Megatheriids appeared during the Late Oligocene...
native to the Americas. It includes anteaters and sloths (which include the extinct groundsloths). The name comes from the Latin word for "hairy". The...
Thalassocnus is an extinct genus of semiaquatic groundsloths from the Miocene and Pliocene of the Pacific South American coast. It is monotypic within...
Nothrotheriidae is a family of extinct groundsloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately 17.49 million...
species: the anteaters, tree sloths, and armadillos. Extinct xenarthrans include the glyptodonts, pampatheres and groundsloths. Xenarthrans originated in...
footprint layers. Other tracks are known for extinct megafauna, including groundsloths (likely either Nothrotheriops or Paramylodon) and Columbian mammoths...
Mylodon is a genus of extinct groundsloth belonging to the family Mylodontidae, known from southern South America. With a total length of 3 to 4 m and...
discoveries bear witness to the early natural history of Organ Cave: giant groundsloth, grizzly bear, nine-banded armadillo, sabre-tooth cat, reindeer and an...
to Bigfoot. Others claim that it is a modern-day sighting of a giant groundsloth, an animal estimated to have gone extinct at the end of the Late Pleistocene...
recorded with a few other mammalian faunas, namely the megalonychid groundsloth Megalonyx, the pocket gopher Geomys, the cricetid Sigmodon, the equin...
deposits from Uruguay, though many were incorrectly referred to the groundsloth Megatherium by early paleontologists. The type species, G. clavipes,...
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