Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Ordo: Pilosa
Subordo: Folivora
Familia: Megalonychidae
Genus: †Megalonyx
Species: M. jeffersonii - M. leptostomus - M. matthisi - M. wheatleyi
Name
Megalonyx Harlan, 1825
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Megalonyx (Greek, "great claw") is an extinct genus of giant ground sloths of the family Megalonychidae endemic to North America from the Hemphillian of the Late Miocene through to the Rancholabrean of the Pleistocene, living from ~10.3 Mya—11,000 years ago, existing for approximately 10.289 million years.,
Taxonomy
The generic name Megalonyx was proposed by future U.S. President Thomas Jefferson in 1797, based on fossil specimens of what later came to be called Megalonyx jeffersonii that he had received from western Virginia. His presentation to the American Philosophical Society that year is often credited as the beginning of vertebrate paleontology in North America.
Megalonyx was named by Harlan (1825). It was assigned to Bradypodidae by Gray (1825); and to Megalonychidae by Harlan (1825), Thurmond and Jones (1981), Carroll (1988), Gaudin (1995) and Cisneros (2005).[1]
Fossil distribution
Its ancestor was Pliometanastes and its closest living relatives are the two-toed sloths (Choloepus). Their remains have been found as far north as Alaska[2] and the Yukon.[3]
Ongoing excavations at Tarkio Valley in southwest Iowa may reveal something of the familial life of Megalonyx. An adult was found in direct association with two juveniles of different ages, suggesting that adults cared for young of different generations.[4][5]
Species
M. leptostomus
M. leptostomus was named by Cope (1893). This species lived from Florida to Texas, north to Kansas and Nebraska, and west to New Mexico, Nevada, Oregon, and Washington. Fossil distribution
* Taunton site, Adams County, Washington. est. age ~3.4—3.3 Mya.
* Wild Horse Butte aka UO 2396, Owyhee County, Idaho. est. age ~2.7—2.1 Mya.
* Buckeye Creek (UCMP V-93067), Douglas County, Nevada. est. age ~4.4—4.5 Mya.
* Kuchta Sand Pit, Yankton County, South Dakota est. age ~2.9—2.1 Mya.
* Meade's Quarries 4 and 5, Crosby County, Texas est. age ~3.7—1.5 Mya.
* Haile 7C, Alachua County, Florida. ~1.6—1.5 Mya.
* Kissimmee River, Okeechobee County, Florida est. age ~2.3 Mya.
(incomplete listing)
References
Citations
1. ^ S. E. Hirschfeld and S. D. Webb. 1968. Bulletin of the Florida State Museum 12(5)
2. ^ Stock, C. (1942-05-29). "A ground sloth in Alaska". Science (AAAS) 95 (2474): 552–553. doi:10.1126/science.95.2474.552.
3. ^ McDonald, H. G.; Harington, C. R.; De Iuliis, G. (September 2000). "The Ground Sloth Megalonyx from Pleistocene Deposits of the Old Crow Basin, Yukon, Canada" (PDF). Arctic (Calgary, Alberta: The Arctic Institute of North America) 53 (3): 213–220. http://pubs.aina.ucalgary.ca/arctic/Arctic53-3-213.pdf. Retrieved 2008-08-16.
4. ^ Semken and Brenzel, http://slothcentral.com/?page_id=2
5. ^ Semken and Brenzel (2007) One Sloth Becomes Three. Newsletter of the Iowa Archeological Society 57(1).
Other sources
* Cope, ED. (1871) Preliminary report on the vertebrata discovered in the Port Kennedy Bone Cave. American Philosophical Society, 12:73-102.
* Cope, ED. (1893) A preliminary report on the vertebrate paleontology of the Llano Estacado. 4th Annual Report on the Geological Survey of Texas: 136pp.
* Hirschfeld, SE. and SD. Webb (1968) Plio-Pleistocene megalonychid sloths of North America. Bulletin of the Florida State Museum Biological Sciences, 12(5):213-296.
