Prehistoric sloths

Megatherium ( ; from Greek () 'great' + () 'beast') is an extinct genus of large ground sloths endemic to South America that lived from the Early Pliocene through the end of the Late Pleistocene. It is best known for the elephant-sized, type species Megatherium americanum, primarily known from the Pampas, but ranging southwards to northernmost Patagonia and northwards to southern Bolivia during the late Middle Pleistocene and Late Pleistocene. Various other species have been described, including those belonging to the Andean subgenus Pseudomegatherium, which range in size from comparable to M.

Megalonychidae is an extinct family of sloths including the extinct Megalonyx. Megalonychids first appeared in the early Oligocene, about 35 million years (Ma) ago, in southern Argentina (Patagonia). There is, however, one possible find dating to the Eocene, about 40 Ma ago, on Seymour Island in Antarctica (which was then still connected to South America). They first reached North America by island-hopping across the Central American Seaway, about 9 million years ago, prior to formation of the Isthmus of Panama about 2.7 million years ago (which led to the main pulse of the Great American Inte

informal group of mammals (fossil)

Mylodon is an extinct genus of ground sloth belonging to the family Mylodontidae, known from southern South America. With a total length of 3 to 4 m and a body mass of 1-2 tonnes, it is one of the largest mylodontids (though it was considerably exceeded in size by the mylodontid Lestodon).

Eremotherium (from Greek for "steppe" or "desert" "beast": ἔρημος "steppe or desert" and θηρίον "beast") is an extinct genus of giant ground sloth in the family Megatheriidae. Eremotherium lived in southern North America, Central America, and northern South America. It was one of the largest sloths, with a body size comparable to elephants, weighing around and measuring about long, slightly larger than its close relative Megatherium.

Thalassocnus is an extinct genus of semiaquatic ground sloths from the Miocene and Pliocene of the Pacific South American coast. It is monotypic within the subfamily Thalassocninae. The five species—T. antiquus, T. natans, T. littoralis, T. carolomartini, and T. yuacensis—represent a chronospecies, a population gradually adapting to marine life in one direct lineage. They are the only known aquatic sloths, but they may have also been adapted to a terrestrial lifestyle. They have been found in the Pisco Formation of Peru, the Tafna Formation of Argentina, and the Bahía Inglesa, Coquimbo, and Ho

thumb|right|Closeup of hand, showing claws thumb|right|Closeup of skull

Megalonyx (Greek, "great-claw") is an extinct genus of ground sloths of the family Megalonychidae, native to North America. It evolved during the Pliocene Epoch and became extinct at the end of the Late Pleistocene, living from ~5 million to ~13,000 years ago. The type species, M. jeffersonii (also called '''Jefferson's ground sloth'''), the youngest and largest known species, measured about in length and weighed up to nearly .

Glossotherium is an extinct genus of large mylodontid ground sloths of the subfamily Mylodontinae. It represents one of the best-known members of the family, along with Mylodon and Paramylodon. Reconstructed animals were between long and possibly weighed up to 1,002.6–1,500 kg. The majority of finds of Glossotherium date from the Middle and Upper Pleistocene, around 300,000 to 10,000 years ago, with a few dating older, as far back Pliocene, about 3.3-3 million years ago. The range included large parts of South America, east of the Andes roughly from latitude 20 to 40 degrees south, leavin

Scelidotherium is an extinct genus of ground sloth of the family Scelidotheriidae, endemic to South America during the Late Pleistocene epoch. It lived from 780,000 to 11,000 years ago, existing for approximately .

Mylodontidae is a family of extinct South American and North American ground sloths within the suborder Folivora of order Pilosa, living from around 23 million years ago (Mya) to 11,000 years ago. This family is most closely related to another family of extinct ground sloths, Scelidotheriidae, as well as to the extant arboreal two-toed sloths, family Choloepodidae; together these make up the superfamily Mylodontoidea. Phylogenetic analyses based on morphology uncovered the relationship between Mylodontidae and Scelidotheriidae; in fact, the latter was for a time considered a subfamily of mylod

Paramylodon is an extinct genus of ground sloth of the family Mylodontidae endemic to North America during the Pliocene through Pleistocene epochs, living from around ~4.9 Mya–12,000 years ago.

thumb|left|Life restoration of Hapalops longiceps and Propalaehoplophorus australis thumb|left|Skeleton

Megalocnus ("great sloth" in Greek) is a genus of extinct ground sloths that were native to Cuba during the Pleistocene and Holocene epochs. They were among the largest of the Caribbean sloths (Megalocnidae), with individuals estimated to have weighed up to 270 kg (595 lbs) to 200 kg (440 lbs), around the size of a black bear when alive. Its relatives include other megalocnid sloths, such as Acratocnus, Mesocnus, Miocnus, Neocnus and Parocnus. The former species M. zile from Hispaniola is currently thought to be a junior synonym of Parocnus serus.

Nothrotheriidae is a family of extinct ground sloths that lived from approximately 17.5 mya—10,000 years ago, existing for approximately . Previously placed within the tribe Nothrotheriini or subfamily Nothrotheriinae within Megatheriidae, they are now usually placed in their own family, Nothrotheriidae. Nothrotheriids appeared in the Burdigalian, some 19.8 million years ago, in South America. The group includes the comparatively slightly built Nothrotheriops, which reached a length of about . While nothrotheriids were small compared to some of their megatheriid relatives, their claws provided

Acratocnus is an extinct genus of Caribbean sloths that were found on Cuba, Hispaniola (today the Dominican Republic and Haiti), and Puerto Rico during the Late Pleistocene and early-mid Holocene.

Nothrotheriops is an extinct genus of ground sloths endemic to North America during the Pleistocene to early Holocene (~2.5 Mya until 10,000 years ago). The genus contains two species, N. shastensis and N. texanus, the former of which is also known as the Shasta ground sloth.

Lestodon is an extinct genus of giant ground sloth native to South America during the Pleistocene epoch. Its fossil remains have primarily been found in the Pampas and adjacent regions. The largest member of the family Mylodontidae, It is estimated to have weighed . It was a herbivore and primarily fed on the grasses and low-growing plants.

Neocnus is an extinct genus of megalocnid sloth, whose species ranged across Cuba and Hispaniola (today split between Haiti and the Dominican Republic). Neocnus was small, with a long tail and a broad trunk, as well as lissome limbs and long claws. This sloth was known for having caudal vertebrae that were broad, a trait shared with other sloths, indicating that this animal, like the tamandua of today, likely used its tail to stand upright. The caniniform teeth of the Neocnus were large and triangular, and its skull was deep and had a large, sagittal crest which, when used with the deep mandib

Catonyx is an extinct genus of ground sloth of the family Scelidotheriidae, endemic to South America during the Pliocene and Pleistocene epochs. It lived from 2.5 Ma to about 10,000 years ago, existing for approximately . The most recent date obtained is about 9600 B.P.

Scelidotheriidae is a family of extinct ground sloths within the order Pilosa, suborder Folivora and superfamily Mylodontoidea, related to the other extinct mylodontoid family, Mylodontidae, as well as to the living two-toed sloth family Choloepodidae. The only other extant family of the suborder Folivora is the distantly related Bradypodidae. Erected as the family Scelidotheriidae by Ameghino in 1889, the taxon was demoted to a subfamily of Mylodontidae by Gaudin in 1995. However, recent collagen sequence data indicates the group is less closely related to Mylodon and Lestodon than Choloepus

Thinobadistes is an extinct genus of ground sloth of the family Mylodontidae endemic to North America during the Miocene-Pliocene epochs (Hemphillian). It lived from 10.3 to 4.9 mya, existing for approximately .

Imagocnus is an extinct genus of ground sloth from the Early Miocene (Burdigalian) Lagunitas Formation of Cuba.

Pseudoglyptodon is a genus of extinct sloths from South America. The type species is Pseudoglyptodon sallaensis.

Promegatherium ("before Megatherium") is a genus of prehistoric xenarthrans that lived in Argentina, during the Late Miocene. This genus is regarded as closely related to the later, and more famous genus, Megatherium, hence the reference in the name. The first specimens of Promegatherium were originally described by the biologist Florentino Ameghino in 1883.

Megalocnidae is an extinct family (alternatively considered to be a superfamily as Megalocnoidea) of sloths, native to the islands of the Greater Antilles from the Early Oligocene to the Mid-Holocene. They are known from Cuba, Hispaniola and Puerto Rico, but are absent from Jamaica. While they were formerly placed in the Megalonychidae alongside two-toed sloths and ground sloths like Megalonyx, recent mitochondrial DNA and collagen sequencing studies place them as the earliest diverging group basal to all other sloths. or as an outgroup to Megatherioidea. They displayed significant diversity i

Prepotherium is an extinct genus of megatheriid ground sloths that lived during the Miocene period. Fossils of Prepotherium have been found in the Collón Curá and Santa Cruz Formations of Argentina.

Pliometanastes is an extinct genus of ground sloths of the family Megalonychidae endemic to North America during the Late Miocene epoch through very early Pliocene epoch (Hemphillian in the NALMA classification). Its fossils have been found in Costa Rica and across the southern United States from California to Florida.

Ahytherium is an extinct genus of megalonychid sloth that lived during the Pleistocene of what is now Brazil. It is a monotypic genus that contains a single species, A. aureum. == Discovery and taxonomy == The almost-complete skeleton of Ahytherium alongside remains of another extinct sloth species, Australonyx, were discovered in Poço Azul, an underwater cave in Chapada Diamantina National Park in 2005. It was described by Castor Cartelle of Pontifícia Universidade Católica de Minas Gerais. The bones, which had a length of about when put together, belong to an animal which presumably was stil

Pelecyodon is an extinct genus of ground sloths from the Early Miocene (Santacrucian) of South America.

Nothrotherium is an extinct genus of medium-sized ground sloth from South America (Bolivia, Brazil and the Ware Formation, La Guajira, Colombia). It differs from Nothrotheriops in smaller size and differences in skull and hind leg bones.

left|thumb|Closeup of the skull with the jugal bone missing Parocnus is an extinct genus of sloth native to Cuba and Hispaniola, belonging to the family Megalocnidae. It was a terrestrial ground sloth, being the second largest Caribbean sloth after Megalocnus, with the body mass of the various species of the genus estimated at around , comparable to a pig.