Fossil range: Oligocene - Holocene
Harlan's Ground Sloth (Paramylodon harlani), a mylodontid
and see text
Ground sloths are a diverse group of extinct sloths, mammals in the edentate superorder Xenarthra. The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra. Chordates ( Phylum Chordata) are a group of Animals that includes the Vertebrates together with several closely related Invertebrates Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands Theria (ˈθɪərɪə from the Greek θηρίον, wild beast is a subclass of Mammals ref> that give birth to live young without See also Evolution of mammals Eutheria ("true beast" are a group of Mammals consisting of Placental mammals plus all extinct Mammals The superorder Xenarthra is a group of Placental mammals (infraclass Eutheria extant today only in the Americas The order Pilosa is a group of placental Mammals extant today only in the Americas The living sloths comprise six Species of medium-sized Mammals that live in Central and South America belonging to the families In Biological classification, family ( Latin The three-toed sloths are the only members of the Bradypus genus and the Bradypodidae family "Megalonychidae" redirects here For the Prehistoric members of this family see Ground sloth#Megalonychidae. Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra. Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra. Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra. The living sloths comprise six Species of medium-sized Mammals that live in Central and South America belonging to the families Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used The superorder Xenarthra is a group of Placental mammals (infraclass Eutheria extant today only in the Americas They may have died out as recently as 1550 in Hispaniola and Cuba (Nowak, 1999), but had long since been extinct on the mainland. Hispaniola (from Spanish, La Española) is the second-largest and most populous Island of the Antilles, lying between the islands of The Republic of Cuba (ˈkjuːbə or) consists of the island of Cuba (the largest and second-most populous island of the Greater Antilles) Isla de la
The bulk of ground sloth evolution took place during the mid to late Tertiary of South America while the continent was isolated. At their earliest appearance in the fossil record, the ground sloths are already distinct at the family level. The formation of the land bridge connecting the American continents in the Miocene allowed a dispersal of forms into North America. A number of mid- to small-sized forms are believed to have dispersed to the Antilles islands either by making short swims or using land bridges that are now submerged. Ground sloths were a hearty group as evidenced by their diverse numbers and dispersals into remote areas given the finding of their remains in southern Patagonia (Last Hope Inlet) and parts of Alaska.
Sloths, and Xenarthrans as a whole, represent one of the more successful South American groups during the Great American Biotic Interchange by establishing a number of taxa in the northern continent. Most taxa moved from North American into South America, with very few going the other way. At least five genera of ground sloth are recognized from North America, and mark the successful colonization of the ground sloths into that continent.
Cryptozoologists often identify the mapinguari, a mythical forest creature of the upper Amazon basin, with a surviving tropical ground sloth or folk memory of these animals. Cryptozoology (from Greek κρυπτός kruptos, "hidden" + Zoology; literally "study of hidden animals" is the study of and search The mapinguari (or mapinguary) ( IPA: /mapiŋgwa'ri/ is a legendary ground-dwelling Sloth -like creature with red Fur living in Folk memories is a term sometimes used to describe stories, Folklore or myths about past events that have passed orally from generation to generation
Paleontologists divide the more than 80 genera of ground sloths in multiple families. Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic In Biological classification, family ( Latin  Note that ground sloths do not form a monophyletic group - megalonychid ground sloths are more related to today's living two-toed sloths - than to any other ground sloths. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor "Megalonychidae" redirects here For the Prehistoric members of this family see Ground sloth#Megalonychidae. An additional family Rathymotheriidae, containing only the genus Rathymotherium, is sometimes listed. Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra.
The megalonychid ground sloths first appeared in the early Oligocene, about 35 million years ago, in southern Argentina (Patagonia). The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 Llao LLaojpg|thumb|250px| Lake Nahuel Huapi, near Bariloche, Argentina With the rise of the land bridge at Panama, these ground sloths began to migrate north as part of the Great American Interchange. Panama, officially the Republic of Panama (República de Panamá) is the southernmost country of Central America. The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central Some lineages of megalonychids increased in size as time progressed. The first species of these were small and may have been partly tree-dwelling, whereas the Pliocene (about 5 to 2 million years ago) species were already approximately half the size of the huge Late Pleistocene Megalonyx jeffersonii from the last ice age. The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends The Late Pleistocene (also known as Upper Pleistocene or the Tarantian) is a stage of the Pleistocene Epoch. "Last glacial" redirects here For the period of maximum glacier extent during this time see Last Glacial Maximum The last glacial period Some West Indian island species were as small as a large cat; their dwarf condition typified both tropical adaptation and their restricted island environment. This small size also enabled them a degree of aboreality. 
Megalonyx, which means "giant claw" is a widespread North American genus, lived past the close of the last (Wisconsin) glaciation, when so many large mammals died out. Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra. "Last glacial" redirects here For the period of maximum glacier extent during this time see Last Glacial Maximum The last glacial period Remains have been found as far north as Alaska.  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. 
The earliest known North American megalonychid, Pliometanastes protistus, lived in Florida and the southern U. Florida ( is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the S. about 9 million years ago, and is believed to have been the predecessor of Megalonyx. Several species of Megalonyx have been named; in fact it has been stated that "nearly every good specimen has been described as a different species". Ground sloths are a diverse group of Extinct Sloths Mammals in the edentate Superorder Xenarthra.  A broader perspective on the group, accounting for age, sex, individual and geographic differences, indicates that only three species are valid (M. leptostomus, M. wheatleyi, and M. jeffersonii) in the late Pliocene and Pleistocene of North America.  Although work by McDonald lists five species. Jefferson's ground sloth has a special place in modern paleontology, for Thomas Jefferson's letter on Megalonyx, read before the American Philosophical Society of Philadelphia, in August 1796, marked the beginning of vertebrate paleontology in North America. Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. Thomas Jefferson (April 13 1743 – July 4 1826 was the third President of the United States (1801–1809 the principal author of the Declaration of Independence The American Philosophical Society is a discussion group founded in 1743 by Benjamin Franklin as an offshoot of his earlier club the Junto. Philadelphia (ˌfɪləˈdɛlfiə Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes  When Lewis and Clark set out, Jefferson instructed Meriwether Lewis to keep an eye out for ground sloths. He was hoping they would find some living in the Western range. Megalonyx jeffersonii was appropriately named after Thomas Jefferson. 
FAMILY MEGALONYCHIDAE Gervais, 1855
The megatheriid ground sloths are relatives of the megalonychids, with which they form the infraorder Megatheria. This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used Megatheriids appeared later in the Oligocene, some 30 million years ago, also in South America. The group includes the heavily-built Megatherium (given its name 'great beast' by Georges Cuvier) and Eremotherium. Megatherium ("Great Beast" was a Genus of Elephant -sized Ground sloths that lived from two million to 8000 years ago Baron Georges Léopold Chrétien Frédéric Dagobert Cuvier ( August 23 1769 &ndash May 13, 1832) was a French naturalist Eremotherium is an extinct genus of Ground sloth. Sources Dinosaur Encyclopedia by Jayne Parsons After Other megatheriids, such as the more slightly built nothrotheres Hapalops and Nothrotheriops, reached a length of about 1. Hapalops is an extinct genus of ground sloth from the late Oligocene of South America Nothrotheriops is a genus of Pleistocene Ground sloth found in North and South America. 2 meters.
The skeletal structure of these ground sloths indicates that the animals were massive. Their thick bones and even thicker joints (especially those on the hind legs) gave their appendages tremendous power that, combined with their size and fearsome claws, provided a formidable defense against predators.
The earliest megatheriid in North America was Eremotherium eomigrans from 2. 2 million years ago. With more than five tons in weight, 6 meters in length, and able to reach as high as 17 feet, it was taller than an African Bush Elephant bull. The African Bush Elephant ( Loxodonta africana) is the larger of the two Species of African elephant. Unlike relatives, this species retained a plesiomorphic extra claw. Cladistics is the hierarchical classification of Species based on evolutionary ancestry While other species of Eremotherium had four fingers with only two or three claws, E. eomigrans had five fingers, four of them with claws up to nearly a foot long. 
The last ground sloths in North America belonging to Nothrotheriops died so recently that their petrified dung (coprolites) has remained undisturbed in some caves, as if it was just recently deposited. A Coprolite is Fossilized animal dung Coprolites are classified as trace fossils as opposed to body fossils as they give evidence for the animal's behaviour (in One of the skeletons, found in a lava tube (cave) at Aden Crater, adjacent to Kilbourne Hole, New Mexico, still had skin and hair preserved, and is now at the Yale Peabody Museum. Lava tubes are natural conduits through which Lava travels beneath the surface of a lava flow expelled by a Volcano during an eruption Kilbourne Hole is a Maar volcanic crater located west of the Franklin mountains of El Paso Texas, in the Potrillo Volcanic Field of Doña Ana County New Mexico ( is a state located in the southwestern region of the United States of America. The American Museum of Natural History in New York City has a sample of dung with a note attached to it that reads "deposited by Theodore Roosevelt". The American Museum of Natural History ( AMNH) located on the Upper West Side, Manhattan, New York, USA is one of the largest and most Theodore Roosevelt (ˈroʊzəvɛlt October 27 1858 January 6 1919 also known as T The largest samples of Nothrotheriops dung can be found in the collections of the Smithsonian Museum. Eventually the Shasta Ground Sloth (Nothrotheriops shastensis) reached the Yukon . Yukon (ˈjuːkɒn is the westernmost and smallest of Canada's three territories.
FAMILY †MEGATHERIIDAE Gray, 1821
The mylodontid ground sloths 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.  Subfossil remains like coproliths, fur and skin have been discovered in some quantities. Subfossil refers to remains whose Fossilization process is not complete either for lack of time or because the condition in which they were buried were not optimal for fossilization
There were rumours during the 19th Century from Patagonia that some ground sloths had survived with one explorer noting that a very large hairy beast that looked like a giant armadillo trotted past them and disappeared into the undergrowth during an expedition. The 19th century of the Common Era began on January 1, 1801 and ended on December 31, 1900, according to the Gregorian calendar Llao LLaojpg|thumb|250px| Lake Nahuel Huapi, near Bariloche, Argentina The Giant Armadillo, also variously Tatou, Ocarro, Tatu-canastra or Tatú Carreta, Priodontes maximus is the largest The local Guaraní Indians of the area had preserved lore of ground sloth-like animals that rested during the day in dens dug with their claws and usually only came out at night. Guaraní are a group of culturally related indigenous peoples of South America, distinguished from the related Tupi by their use of the Guaraní language
FAMILY †MYLODONTIDAE Gill, 1872
Together with the Mylodontidae and the engimatic Pseudoprepotherium, the scelidotheriid ground sloths form the superfamily Mylodontoidea. Taxonomic rank ( rank, category, taxonomic category is an abstract term used in the Scientific classification, or Taxonomy, of organisms Chubutherium is an ancestral and very plesiomorphic member of this family and does not belong to the main group of closely-related genera. Chubutherium ferelloii is an extinct species of Ground sloth (Cattoi 1962 Cladistics is the hierarchical classification of Species based on evolutionary ancestry
FAMILY †SCELIDOTHERIIDAE Ameghino, 1889
The orophodontid ground sloths constitute a rather small but quite distinct group. Chubutherium ferelloii is an extinct species of Ground sloth (Cattoi 1962 In Phylogenetics, a basal Clade is the earliest clade to branch in a larger clade it appears at the base of a cladogram Scelidotherium is a Genus of South American Pliocene - Pleistocene Ground sloths characterized by an elongated superficially They are classified as a distinct mylodontan superfamily Orophodontoidea, the sister taxon to the Mylodontoidea. Taxonomic rank ( rank, category, taxonomic category is an abstract term used in the Scientific classification, or Taxonomy, of organisms Cladistics is the hierarchical classification of Species based on evolutionary ancestry
FAMILY †OROPHODONTIDAE Ameghino, 1895