State Fossil of West Virginia
Giant Ground Sloth (common name) Megalonyx jeffersonii (scientific name) STATUS Official DESCRIPTION Megalonyx jeffersonii is an extinct species of giant ground sloth. Living approximately 10,000 to 150,000 years ago, this giant sloth was one of the megafauna that inhabited the Earth during the Pleistocene period. It lived from coast to coast across all of present-day North America, ranging as far north as Alaska and the Yukon, and as far south as Florida and Mexico. Also known as Jefferson’s ground sloth, this is the largest known species of the genusMegalonyx. STATE SYMBOL In 1797, Thomas Jefferson gave a lecture on Megalonyx to the American Philosophical Society in Philadelphia. Jefferson, who at that time was vice president of the United States, was also president of the American Philosophical Society. Jefferson had studied bones sent to him from present-day Monroe County, West Virginia. Jefferson’s lecture is said to have started the study of vertebrate paleontology in North America. The importance of this species and its discovery to paleontology, West Virginia history, and American history led West Virginia to designate Megalonyx jeffersonii the official state fossil in March 2008. NAME ORIGIN Thomas Jefferson proposed the genus name for this animal in 1799, and in 1804, the then-president was credited with discoveringMegalonyx. The genus name Megalonyx comes from the Greek words μεγάλο (megalo), which means "large," and νύχι (nychi), meaning "claw" or "hoof." French zoologist and author Anselme Gaëtan Desmarest (1784–1838) named the species jeffersonii in 1822 to honor Thomas Jefferson. BIOLOGY/ANATOMY This giant ground sloth grew to a length of about 8 to 10 feet (2.5 to 3 m). A heavy animal, Megalonyx jeffersonii was the size of a modern elephant, weighing up to 800 pounds (360 kg). This flat-footed mammal used its long, strong tail to support its massive body, sometimes standing upright to feed. Its short, broad skull contained a massive jaw and large teeth for tearing through rough foliage. In addition to its claws being large, they were also curved and well developed, allowing the giant sloth to manipulate branches. EVOLUTION/EXTINCTION Like all Pleistocene megafauna, giant ground sloths became extinct at the end of that geologic age. This was also the end of the last ice age, approximately 10,000 years ago. The closest living relatives toMegalonyx jeffersonii are the modern two-toed tree sloths of South America. MODERN DISCOVERY The Megalonyx bones sent to Thomas Jefferson came from a limestone cave in what is now southern West Virginia. Although initially misidentifying the species as an extinct lion, Jefferson realized his error before presenting a paper to the American Philosophical Society in which he described the yet unnamed species. In 1799, Caspar Wistar (1761–1818), an American physician and anatomist, identified the bones as belonging to a giant ground sloth. Megalonyx fossils have since been discovered in at least three other caves in West Virginia, and various species of this prehistoric mammal have been found in other locations in North America. INTERESTING FACTS The first learned society in the United States, the American Philosophical Society, was founded by Benjamin Franklin in 1743. For more than two and a half centuries, the organization has promoted the humanities and the sciences in America. Its elected members are top scholars in a wide variety of fields. In 1811, Megalonyx jeffersonii bones were discovered in Van Buren County, Tennessee. The area is now a 400-acre natural area named Big Bone Cave in honor of the giant sloth. The mammal’s skeleton, the only known specimen of a giant ground sloth with a complete pelvis, is now displayed at the Academy of Natural Sciences in Philadelphia. The Thomas Jefferson Fossil Collection at the Academy of Natural Sciences in Philadelphia contains specimens previously obtained by Jefferson. Fossils acquired by the academy in 1849 include the American megalodon,Megalonyx, woolly mammoth, and five other species of prehistoric mammals.
	Click to enlarge an image Illustration of Giant Ground Sloth Giant Ground Sloth Skeleton Frontal View of Giant Ground Sloth CLASSIFICATION Kingdom: Animalia Phylum: Chordata Class: Mammalia Superorder: Xenarthra Order: Pilosa Family: Megalonychidae Subfamily: Megalonychinae Genus: Megalonyx Species: M. jeffersonii
	Author: World Trade Press