Editing Ground sloth (section)

{{Short description|Diverse group of extinct sloth species}}
{{Paraphyletic group
| auto = yes
| name = Ground sloths
| fossil_range = {{Fossil range|35|0.005}}<small>Late [[Eocene]] –  [[Holocene]]</small>
| image = Ground sloths.jpg
| image_caption = [[American Museum of Natural History]] mounts of (from left) ''[[Megalocnus]] rodens'', ''[[Scelidotherium]] cuvieri'', ''[[Megalonyx]] wheatleyi'', ''[[Glossotherium]] robustus''
| parent = Folivora
| includes_text = Families
| includes = 
* †[[Megalocnidae]] (in part)
* †[[Megalonychidae]]
* †[[Megatheriidae]]
* †[[Nothrotheriidae]]
* †[[Mylodontidae]]
* †[[Scelidotheriidae]]
}}

'''Ground sloths''' are a diverse group of [[extinct]] [[sloth]]s in the [[mammal]]ian [[superorder]] [[Xenarthra]]. They varied widely in size with the largest, belonging to genera ''[[Lestodon]]'', ''[[Eremotherium]]'' and ''[[Megatherium]]'', being around the size of [[elephants]]. Ground sloths represent 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, they 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]].<ref>C.M. Hogan (2008)</ref><ref>{{Cite journal |last=Stock |first=Chester |date=1942-05-29 |title=A Ground Sloth in Alaska |url=http://dx.doi.org/10.1126/science.95.2474.552 |journal=Science |volume=95 |issue=2474 |pages=552–553 |bibcode=1942Sci....95..552S |doi=10.1126/science.95.2474.552 |issn=0036-8075 |pmid=17790868|url-access=subscription }}</ref><ref>{{Cite journal |last1=McDonald |first1=H.G. |last2=Harington |first2=C.R. |last3=De Iuliis |first3=G. |date=2000-01-01 |title=The Ground Sloth, Megalonyx, from Pleistocene Deposits of the Old Crow Basin, Yukon, Canada |journal=Arctic |volume=53 |issue=3 |doi=10.14430/arctic852 |issn=1923-1245 |doi-access=free}}</ref> 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|end-Pleistocene extinction event]] around 12,000 years ago, simultaneously with the majority of other large animals in the Americas. Their extinction has been posited to be the result of hunting by recently arrived humans and/or climate change.<ref name="Fiedal">{{cite book |last=Fiedal |first=Stuart |series=Vertebrate Paleobiology and Paleoanthropology |title=American Megafaunal Extinctions at the End of the Pleistocene |publisher=[[Springer Science+Business Media|Springer]] |year=2009 |isbn=978-1-4020-8792-9 |editor-last=Haynes |editor-first=Gary |pages=21–37 |contribution=Sudden deaths: The chronology of terminal Pleistocene megafaunal extinction |doi=10.1007/978-1-4020-8793-6_2}}</ref><ref>{{Cite web |last=Mason |first=Betsy |date=August 1, 2005 |title=Humans Drove Giant Sloths to Extinction |url=https://www.science.org/content/article/humans-drove-giant-sloths-extinction |access-date=2022-10-02 |website=www.science.org |language=en}}</ref> A number of [[kill site]]s are known where humans butchered ground sloths dating just prior to their extinction.

The [[Megalocnidae|Caribbean ground sloths]], the most recent survivors, lived on [[Cuba]] and [[Hispaniola]], possibly until 1550&nbsp;BCE. However, [[radiocarbon dating]] suggests an age of between 2819 and 2660&nbsp;BCE for the last occurrence of ''[[Megalocnus]]'' in [[Cuba]].<ref name="MacPhee">{{cite journal |last1=MacPhee |first1=R.D.E. |author2=Iturralde-Vinent, M.A. |author3=Vázquez, O.J. |date=June 2007 |title=Prehistoric Sloth Extinctions in Cuba: Implications of a New 'Last' Appearance Date |url=https://bioone.org/journals/caribbean-journal-of-science/volume-43/issue-1/cjos.v43i1.a9/Prehistoric-Sloth-Extinctions-in-Cuba--Implications-of-a-New/10.18475/cjos.v43i1.a9.short |journal=[[Caribbean Journal of Science]] |publisher=College of Arts and Sciences, [[University of Puerto Rico at Mayagüez|University of Puerto Rico]] |volume=43 |issue=1 |pages=94–98 |doi=10.18475/cjos.v43i1.a9 |access-date=11 May 2009 |s2cid=56003217|url-access=subscription }}</ref> They survived 5,000–6,000&nbsp;years longer in the [[Caribbean]] than on the American mainland, which correlates with the later colonization of this area by humans.<ref name="Steadman_2005">{{cite journal |last1=Steadman |first1=D.W. |author2=Martin, P.S. |author3=MacPhee, R.D.E. |author4=Jull, A.J.T. |author5=McDonald, H.G. |author6=Woods, C.A. |author7=Iturralde-Vinent, M. |author8=Hodgins, G.W.L. |author1-link = David Steadman |author2-link=Paul Schultz Martin |title=Asynchronous extinction of late Quaternary sloths on continents and islands |journal=[[Proceedings of the National Academy of Sciences]] |volume=102 |issue=33 |pages=11763–11768 |publisher=[[United States National Academy of Sciences]] |date=2005-08-16 |doi=10.1073/pnas.0502777102 |pmid=16085711 |pmc=1187974 |bibcode=2005PNAS..10211763S |doi-access=free }}</ref>