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 mylodontids. However, molecular sequence comparisons were needed for the correct placement of Choloepodidae. These studies have been carried out using mitochondrial DNA sequences as well as with collagen amino acid sequences. The latter results indicate that Choloepodidae is closer to Mylodontidae than Scelidotheriidae is. The only other living sloth family, Bradypodidae, belongs to a different sloth radiation, Megatherioidea.
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).
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.
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.
Lestobradys is an extinct genus of ground sloth, which existed in Uruguay during the Late Miocene period; Huayquerian in the South American land mammal age (SALMA). The type species is L. sprechmanni, found in the Camacho Formation of Uruguay.
Ahytherium is an extinct genus of megalonychid sloth that lived during the Pleistocene of what is now Brazil. It contains a single species, A. aureum.
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.
Megatheriinae is a subfamily of the Megatheriidae, an extinct family of ground sloths that lived from the Middle Miocene to the Early Holocene.
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.
Pattersonocnus is an extinct genus of megalonychid sloth that lived during the Miocene in Venezuela 11.6 million years ago. The genus contains one known species, Pattersonocnus diazgameroi. Fossils have been found in the Urumaco Formation of Venezuela.
Proeremotherium is an extinct genus of megatheriine ground sloths in the family Megatheriidae. It lived during the Late Miocene and Early Pliocene of what is now Venezuela. So far, two largely complete skulls have been recovered in the Falcón Basin in Venezuela. The finds identify the animals as medium-sized representatives of the Megatheriidae. In the cranial anatomy, Proeremotherium resembles the later and giant Eremotherium. It is therefore assumed that the two ground sloths are directly related to each other.
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.
Baraguatherium is an extinct genus of ground sloths of the family Mylodontidae that lived during the Early Miocene of what is now Venezuela. It dates to the Early Miocene, around 20.44 to 15.97 million years ago and represents the oldest representative of its family in the northern part of South America to date. The structure of the teeth suggests that the genus represents a rather basal form within the Mylodontidae. Unlike other mylodonts, which tended to prefer open grasslands, Baraguatherium lived in a riverine, coastal tropical rainforest.
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.
Lakukullus is an extinct genus of nothrotheriid ground sloths that lived during the Middle Miocene around 13.8 to 11.8 million years ago of what is now Bolivia.
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.
Magdalenabradys is an extinct genus of mylodontid ground sloths that lived during the Middle Miocene and Early Pliocene of what is now Colombia and Venezuela. Fossils have been found in the Villavieja Formation of the Honda Group in Colombia, and the Codore and Urumaco Formations of Venezuela.
Ocnotherium is an extinct genus of ground sloth known from the Late Pleistocene of Brazil, belonging to the family Mylodontidae, containing the species Ocnotherium giganteum. It is a member of the subfamily Mylodontinae, but its relationship to other members of that subfamily are uncertain. It had osteoderms embedded within its skin, like some other mylodontids. It was likely a mixed feeder, and may have been adapted to digging.
