Megatherium was a giant ground sloth that evolved in South America. It lived in the Pliocene and Pleistocene periods.
Megatherium was one of the largest land mammals known, standing about 6 meters tall on its hind legs and weighing an estimated 4 tonnes. Its huge claws on its arms were probably used to grasp branches, pulling them down for the sloth to feed upon.
Megatherium evolved during the Pliocene, when South America was still an island continent. When North and South America collided with each other, species from both continents began colonizing each other's territory, which has been called the Great American (Biotic) Interchange. During this event, many species became extinct from the new competition. However, ground sloths remained largely unaffected, and Megatherium thrived on both continents. Human hunting may have finally driven them to extinction.
Megatherium and other ground sloths were part of the superorder Xenarthra, along with contemporary glyptodonts and modern sloths and armadillos.
The type species, Megatherium americanum, was described by Georges Cuvier in 1796. Since then, five other species have been discovered, of varying sizes and time ranges.
Megatherium was chiefly a herbivore, feeding on grasses and leaves. However, it has been suggested that Megatherium could have also been a carnivore, stealing the kills of other predators and even hunting down prey themselves using their huge claws. Scientists from Montevideo, Uruguay first proposed this, examining the shape of the limb bones and points of muscle attachment. They found that the sloth's limbs may have been adapted for speed instead of strength. However, this idea remains controversial.
- Bargo, M. S. (2001). "The ground sloth Megatherium americanum: Skull shape, bite forces, and diet". Acta Palaeontologica Polonica 46 (2): 173–192.
- Webb, S. David (23 August 2006). "The Great American Biotic Interchange: Patterns and Processes". Annals of the Missouri Botanical Garden (St. Louis, Missouri: Missouri Botanical Garden) 93 (2): 245–257. doi:10.3417/0026-6493(2006)93[245:TGABIP]2.0.CO;2. ISSN 0026-6493. http://www.bioone.org/doi/full/10.3417/0026-6493(2006)93%5B245:TGABIP%5D2.0.CO%3B2?cookieSet=1.
- Martin, P. S. (2005). Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America. University of California Press. ISBN 0520231414. http://books.google.com/?id=eThoCsL1hRAC.
- Saint-André, P. A.; De Iuliis, G. (2001). "The smallest and most ancient representative of the genus Megatherium Cuvier, 1796 (Xenarthra, Tardigrada, Megatheriidae), from the Pliocene of the Bolivian Altiplano.". Geodiversitas 23 (4): 625–645. Retrieved 22 July 2012.
- Fariña, R. A.; R. E. Blanco (1996). "Megatherium, the stabber". Proceedings of the Royal Society of London 263 (1377): 1725–1729. doi:10.1098/rspb.1996.0252. JSTOR 50663. PMID 9025315.