Mylodontidae — Details

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Overview

Comprehensive Description

Comprehensive Description

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The family Mylodontidae contains large ground sloths and belongs to the order Xenarthra, which also includes armadillos, glyptodonts, anteaters, tree-sloths and ground-sloths. Species in Xenarthra are known for low body temperatures and massive limb bones with well-developed claws. They have a second set of ribs that connects their regular ribs to their breastbone (sternum), and their hip and tail vertebrate are fused to form a solid structure called a synsacrum. All Xenarthrans lack an appendix.

Species in the Mylodontidae were the most successful during the Plio-Pleistocene (about 2.5 million to 10,000 years ago). They were found throughout South America and some (such as Paramylodon) reached as far north as North America. They were about 1.8m long and weighed about 1.5 tons. Like other sloths mylodonts were herbivores (only ate plants), and their lobe-like teeth with flat chewing surfaces suggests they were grazers that fed on grasses. Fossil dung of Mylodon darwinii found in a cave in Chile contained crushed blades and stems of grasses and sedges.

Scelidotherium and Paramylodon represent two different subfamilies of the Mylodontidae. Scelidotherium and its close relatives have long narrow skulls while Paramylodon and its relatives have wide broad skulls. The difference in skull shape suggests they fed differently. Scelidotherium was more selective in the parts of plants it ate while Paramylodon was more of a generalist and consumed all of the plant.

Some members of the Mylodontidae family, like the North American Paramylodon harlani, had small pebble-like bones in their skin called dermal ossicles. These were thought to help protect against predators.

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Wikipedia

Mylodontidae

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Mylodontidae is a family of extinct mammals within the order of Pilosa and suborder Folivora living from approximately 23 mya—11,000 years ago, existing for approximately 22.89 million years.[1] This family of ground sloths is related to the other families of extinct ground sloths, being the Megatheriidae, the Nothrotheriidae, the Orophodontidae and the Scelidotheriidae. The only extant families of the suborder Folivora are the Bradypodidae and the Megalonychidae. Phylogenetic analyses using homologous sequences from all extant edentate groups indicates that the Mylodontidae were closer related to Megalonychidae than to Bradypodidae.[2]

The mylodontids together with their relatives the scelidotheriids and the orophodontids form the Mylodonta, the second radiation of ground sloths. The discovery of their fossils in caverns associated with human occupation lead some early researchers to theorize that the early humans built corrals when they could procure a young ground sloth, to raise the animal to butchering size.[3] However, radiocarbon dates do not support simultaneous occupation of the site by humans and sloths.[4] Subfossil remains like coproliths, fur and skin have been discovered in some quantities.

FAMILY †Mylodontidae Gill, 1872


Footnotes

  1. ^ http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=43629&is_real_user=1 Mylodontidae: Paleobiology Database
  2. ^ Hoss, Matthias; Dilling, Amrei; Currant, Andrew; Paabo, Svante (9 Jan 1996). "Molecular phylogeny of the extinct ground sloth Mylodon darwinii". Proceedings of the National Academy of Sciences 93 (1): 181–185. doi:10.1006/mpev.2000.0860. PMID 11161746. http://www.pnas.org/content/93/1/181.abstract. Retrieved 2009-12-28. 
  3. ^ A.S. Woodward (1900)
  4. ^ Naish, Darren (28 Nov 2005). "Fossils explained 51: Sloths". Geology Today (Geologists' Association, Geological Society of London and Blackwell Publishing) 21 (6): 232–238. doi:10.1111/j.1365-2451.2005.00538.x. http://www3.interscience.wiley.com/journal/118652140/abstract. Retrieved 2009-01-29. 

References

  • 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.
  • Harrington, C.R. (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
  • Kurtén, Björn and Anderson, Elaine (1980): Pleistocene Mammals of North America. Columbia University Press, New York. ISBN 0-231-03733-3
  • McKenna, Malcolm C. & Bell, Susan K. (1997): Classification of Mammals Above the Species Level. Columbia University Press, New York. ISBN 0-231-11013-8
  • 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.
  • White, J.L. & MacPhee, R.D.E. (2001): The sloths of the West Indies: a systematic and phylogenetic review. In: Woods, C.A. & Sergile, F.E. (eds.): Biogeography of the West Indies: Patterns and Perspectives: 201-235.
  • 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.
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