Temporal range: Oligocene – Holocene
|Fossils of different ground sloths at the American Museum of Natural History in New York|
The term "ground sloth" is used as opposed to the much smaller living "tree sloths". Their most recent survivors lived in the Caribbean Antilles, where they may have survived until about 2819 and 2660 BC. This was the last known occurrence of Megalocnus in Cuba. Ground sloths had been extinct on the mainland of North and South America for 10,000 years or more. Their later survival in the Caribbean correlates with the later colonization of this area by humans. Some island sloth populations persisted 5,000-6,000 years longer than their continental mainland relatives. This fits the global pattern of late Quaternary large vertebrate extinction due to human dispersal.
Most ground sloth evolution took place during the mid to late Tertiary 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. The presence of intervening islands between the American continents in the Miocene allowed a dispersal of forms into North America. A number of mid- to small-sized forms are believed to have previously dispersed to the Antilles islands either by making short swims or using land bridges. Ground sloths were a hardy group: their numbers and dispersals into remote areas are evidence of this. Remains have been found in Patagonia (Cueva del Milodón), and parts of Alaska.
Sloths, and xenarthrans as a whole, were one of the more successful South American groups during the Great American Biotic Interchange. In general, during the interchange, many more taxa moved from North America into South America than in the other direction. However,at least five genera of ground sloths have been identified in North American fossils; these are examples of successful migration to the north.
Typical examples[change | change source]
References[change | change source]
- MacPhee R.D.E; Iturralde-Vinent M.A. & Vázquez O.J. (2007). "Prehistoric sloth extinctions in Cuba: implications of a new "last" appearance date". Caribbean Journal of Science 43 (1): 94–98. http://caribjsci.org/June07/43_94-98.pdf. Retrieved 11 May 2009.
- Fiedal, Stuart (2009). "Sudden deaths: the chronology of terminal Pleistocene megafaunal extinction". In Haynes, Gary. American Megafaunal Extinctions at the End of the Pleistocene. Springer. pp. 21–37. . . http://www.springerlink.com/content/l225628681672725/?p=5af1eb7387d443a2b514b284c646efa7&pi=1.
- Steadman D.W. et al (2005). "Asynchronous extinction of late Quaternary sloths on continents and islands". Proceedings of the National Academy of Sciences USA 102 (33): 11763–11768. . . . http://www.pnas.org/content/102/33/11763.full.pdf.
- Hogan C.M. 2008. Cueva del Milodon, Megalithic Portal. Retrieved 2008-APR-13