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(Xenarthra: Megalonychidae) from the Pleistocene (Late Irvingtonian) Camelot Local Fauna, Dorchester County, South Carolina
Introduction
In the late 179Os Thomas Jefferson presented a paper to the American Philosophical Society on skeletal remains of an animal from western Virginia. He described the bones from an animal "of the clawed kind." (Jefferson 1799]. A large claw core in the remains prompted Jefferson to name the beast Megalonyx, meaning "great claw." Jefferson assumed that the creature must have been some type of large carnivore/ such as a lion. However, similar finds in South America led to the correct identification of the animal as a large ground sloth. The species was subsequently named Megalonyx jeffersonii (Desmarest 1822) in honor of Thomas Jefferson. Since that time/ numerous other species of Megalonyx have been described and synonomized.
Fossil ground sloths of the genus Megalonyx range from the late Miocene [Hemphillian, ca. six million years ago] to the late Pleistocene (Rancholabrean, ca. 12/000 years ago) (McDonald et. al 2000/ Woodburne 2004). The genus is known from over 152 sites in North America (McDonald 2003) from Florida (Hulbert 2001) to Alaska (Stock 1942). Fossils of Megalonyx from the late Blancan, Irvingtonian, and Rancholabrean North American Land Mammal Ages (NALMA] have been collected in South Carolina. Up to three species of Megalonyx from the Plio -Pleistocene of South Carolina may be represented by the chronospecies M. leptostomus, M. wheatleyi, M. jeffersonii as proposed by McDonald (1977).
Although Megalonyx is a common component of many North American Pleistocene faunas, fossil elements of ground sloth are usually not this abundant (H.G. McDonald, pers. comm.). Typically, isolated teeth comprise the representative Megalonyx fossils for any given site. Without associated mandibles, the molariform teeth of sloths are difficult to assign position within the ramus. As such, isolated teeth are usually of little value besides documenting occurrence of the taxon at a particular locality.
More than 200 years after Thomas Jefferson made his discovery, a new site in the coastal plain of South Carolina has yielded an unusually large sample of Megalonyx remains. This paper reports over 250 elements of Megalonyx from the late Irvingtonian Camelot Local Fauna in Dorchester County, South Carolina. Initial study suggested that this sample was a population of smaller-sized M. jeffersonii, but other...