Mylodon is a genus of extinct ground sloth belonging to the family Mylodontidae, known from the Pampas and Patagonia in Chile and Argentina in southern South America. With a total length of 3 to 4 m, it is one of the best-known and largest representatives of the group. The oldest finds probably date to the Lower Pleistocene; however, most of the fossil remains date from the Upper Pleistocene period. One of the most important sites of this phase is the Cueva del Milodón in southern Chile. Shortly after, about 10,200 BP, Mylodon became extinct. At this point in time, it coexisted with the first human colonists in America.
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. Ground sloths varied widely in size, with the largest genera Megatherium and Eremotherium being around the size of elephants. Ground sloths are a paraphyletic group, as living tree sloths are thought to have evolved from ground sloth ancestors.
Megatheriidae is a family of extinct ground sloths that lived from approximately 23 mya—11,000 years ago.
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 is, and thus it has been elevated back to full family status by Presslee et al. (2019).
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 0.67 million years.
The order Pilosa is a clade of xenarthran placental mammals, native to the Americas. It includes anteaters and sloths. The name comes from the Latin word for "hairy".
Choloepus is a genus of xenarthran mammals of Central and South America within the monotypic family Choloepodidae, consisting of two-toed sloths, sometimes also called two-fingered sloths. The two species of Choloepus, Linnaeus's two-toed sloth and Hoffmann's two-toed sloth, were formerly believed on the basis of morphological studies to be the only surviving members of the sloth family Megalonychidae, but have now been shown by molecular results to be closest to extinct ground sloths of the family Mylodontidae.
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. 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. Some megalonychid lineages increased in size as time passed. The first species of these were small and may have been partly tree-dwelling, whereas the Pliocene species were already approximately half the size of the huge Late Pleistocene Megalonyx jeffersonii from the last ice age.
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 3 and 4 metres 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, leaving out the Amazon Basin in the north. In western South America, finds are also documented north of the equator. The animals largely inhabited the open landscapes of the Pampas and northern savanna regions.
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.
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 2.49 million years. The most recent date obtained is about 9600 B.P.
Mylodontinae is an extinct subfamily of ground sloths that lived from the Early Miocene to the Early Holocene epochs.
Nematherium is an extinct genus of ground sloth belonging to Mylodontoidea, it is either considered to be a member of Mylodontidae or Scelidotheriidae. It lived during the Middle Miocene epoch (Santacrucian). Fossils have been found in the Cura-Mallín Formation of Chile and the Santa Cruz and Sarmiento Formations of Argentina.
Valgipes is an extinct genus of scelidotheriid ground sloth, endemic to intertropical Brazil and Uruguay during the Late Pleistocene. Thought to have been a forest-dwelling browser, Valgipes is a monotypic genus with a complex and long taxonomic history, and is a close relative of Catonyx and Proscelidodon.
Pseudoprepotherium is an extinct genus of sloths of the family Mylodontidae. It was widespread across northern South America during the Early to Late Miocene epoch around 21 to 5.3 million years ago. Fossils of the animal have been found in Brazil, Venezuela, and Peru. Pseudoprepotherium lived in a tropical climate with a water-rich environment. Their known remains are limited to limb bones, except for a few skulls and teeth. Based on these remains, they were most likely medium to large-sized mylodontid. The genus was described in 1961 and currently contains three species, which were originally assigned to the genus Prepotherium.
Archaeomylodon is an extinct genus of mylodontine ground sloths that lived during the Middle Pleistocene of what is now Argentina. It is known so far only from a single skull, which in its dimensions corresponds to those of the giant Lestodon. However, the skull differs from this one by its narrower and higher snout. In addition, the anterior canine teeth, which are usually large in many mylodonts, are greatly reduced. The find comes from the Pampa region of South America and was deposited in about 700,000 years old sediments.
Urumacotherium is an extinct genus of ground sloths of the family Mylodontidae. It lived from the Middle Miocene to the Early Pliocene of what is now Brazil, Peru and Venezuela.
Simomylodon is an extinct genus of ground sloths from the family Mylodontidae. It lived from the Late Miocene to the Middle Pliocene of what is now Bolivia and Argentina, 5.3 to 2.8 million years ago. The most important find material comes from the central Altiplano in Bolivia and includes several skulls and dentition remains. Thus, the so far documented body skeleton is the best known and most significant of a Miocene representative of the Mylodontidae. On the basis of the remains, it can be concluded that it is a rather small member of the Mylodontidae. The construction of the limbs supports ground-dwelling locomotion, but this does not exclude occasional digging or climbing. The type and only known species is Simomylodon uccasamamensis.
Bolivartherium is an extinct genus of mylodontine mylodontid sloth that lived during the Late Miocene and Late Pliocene in what is now Venezuela. Fossils have been found in the Codore and Urumaco Formations of Venezuela.
Neonematherium is an extinct genus of scelidotheriid ground sloths that lived in Argentina, Chile, and Colombia during the Early to Late Miocene. Fossils have been found in the Honda Group of Colombia, and the Río Frías Formation of Chile.
