Class Mammalia Superorder Xenarthra Family Megalonychidae
Temporal and Geographic Range: “Ice Age”: Middle - Late Pleistocene Epoch (150,000 - 11,000 years before present), eastern North America
Fun Facts: - Megalonyx jeffersonii is named for President Thomas Jefferson and literally means, “Jefferson’s Big Claw.” - Megalonyx jeffersonii fossils are known from several nearby localities, including Saltville, Virginia and here in Sullivan County, Tennessee. - Ground sloths spent most of their time moving on all four limbs, but were able to raise up on their hind legs to reach for branches and for defense. - Giant ground sloth remains are often found in caves which suggests that the animals regularly used caves when they were alive. - All sloths (modern tree sloths and extinct giant ground sloths) are known only from the Americas. - Giant Ground Sloths went extinct in North America only 11,000 years ago and were encountered by early American peoples. There is even some evidence that Megalonyx jeffersonii was on the menu of early Americans. - Sloths are part of the Xenarthra, a taxonomic group of mammals including armadillos, anteaters, and several bizarre extinct forms. Most xenarthrans (past and present) are exclusive to Central and South America, though Megalonyx was a uniquely North American giant ground sloth. - Megalonyx jeffersonii was a national sensation in the early 19th Century and helped kickstart the science of paleontology in the U.S. Interestingly, however, our modern understanding of extinction had yet to receive widespread understanding… President Jefferson specifically requested from Lewis and Clark that they look for living ground sloths during their expedition!