| Acratocnus | |
|---|---|
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| Acratocnus ye skull | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Pilosa |
| Family: | † Megalocnidae |
| Genus: | † Acratocnus Anthony 1916 |
| Type species | |
| †Acratocnus odontrigonus Anthony, 1916 | |
| Species | |
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| Synonyms | |
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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.
The genus was first described by American paleontologist Harold Elmer Anthony in 1916 based on the species A. odontrigonus, which was found in cave deposits in Puerto Rico. [1] Acratocnus antillensis was first described by William Diller Matthew in 1931. The species was identified based on fossil remains found in various locations in Cuba, including the paleontological deposit Las Llanadas, Sancti Spíritus Province. [2] [3] Acratocnus ye was first described by Ross D. E. MacPhee, Jennifer L. White, and Charles A. Woods in 2000. The species was identified based on fossil remains found in various locations in Haiti, including the type locality at Trouing Vape`Deron, Plain Formon, Département du Sud. [4] The holotype specimen, UF170533, consists of a skull and mandible. [5] Acratocnus simorhynchus was first described in 2002. The species was identified based on fossil remains found in Cueva del Perezoso, located in Jaragua National Park, Pedernales Province, Dominican Republic. [6] The holotype, catalogued as ALF 7194, includes an unusually well-preserved skull, mandible, and post-cranial elements. [6]
Like all of the Antillean sloths, Acratocnus was formerly thought on the basis of morphological evidence to be a member of the family Megalonychidae, which was also thought to include Choloepus , the two-toed tree sloths. Recent molecular evidence has clarified that Caribbean sloths represent a separate basal branch of the sloth radiation, [7] [8] now placed in the family Megalocnidae. [7]
Acratocnus ye and A. odontrigonus have been estimated to weigh approximately 15 kilograms (33 lb), while A. antillensis is estimated to be somewhat smaller at around 10 kilograms (22 lb). [9] All species of Acratocnus were somewhat larger than living tree sloths, though small in comparison to mainland ground sloths. [5] The skulls of Acratocnus are markedly domed along their sagittal crests. [4] The skull of A. antillensis is distinguished from other species within the genus Acratocnus by its prominent palatine foramina and a short, pointed symphyseal spout. [10] [11] The skull of A. simorhynchus is distinguished by its prominent frontal sinuses, resulting in a foreshortened snout. The species also exhibits a pronounced medio-lateral flare of the rostrum, a short symphyseal spout, and deep mandibular corpus. [12] [13] The skull of A. ye is distinguished by its flattened nose, giving it a "snub nosed" look. [5]
Species of Acratocnus inhabited forested environments. The various species are though to have been semi-arboreal, having spent some of their time in trees and some on the ground [5] , with their hooked claws being used both for climbing and terrestrial foraging. [12]
The various species of Caribbean sloths are thought to have become extinct following human arrival to the Caribbean during the mid-Holocene around 6,000 years ago based on the timing of the last radiocarbon dates of Caribbean sloths. [14] Several radiocarbon dates of A. antiliensis on Cuba support the presence of the species on the island up until human arrival. Remains of Caribbean sloths have been found in a number of archaeological sites suggesting that they may have been consumed by the earliest inhabitants of the Caribbean, although evidence of hunting is inconclusive. [15]
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. They varied widely in size with the largest, belonging to genera Lestodon, Eremotherium and Megatherium, being around the size of elephants. Ground sloths represent a paraphyletic group, as living tree sloths are thought to have evolved from ground sloth ancestors.
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.
Gymnogyps is a genus of New World vultures in the family Cathartidae. There are five known species in the genus, with only one being extant, the California condor.
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.
Neocnus is an extinct genus of megalocnid sloth, whose species ranged across Cuba and Hispaniola. Neocnus was small, with a longe 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 mandible likely allowed strong exertion by the masticatory muscles.
Megalocnus 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 to 200 kg, around the size of a black bear when alive. Its relatives include other megalocnid sloths, such as Acratocnus, Mesocnus, Miocnus, Neocnus andParocnus. The former species M. zile from Hispaniola is currently thought to be a junior synonym of Parocnus serus.
Imagocnus is an extinct genus of ground sloth from the Early Miocene (Burdigalian) Lagunitas Formation of Cuba.
The Caribbean bioregion is a biogeographic region that includes the islands of the Caribbean Sea and nearby Atlantic islands, which share a fauna, flora and mycobiota distinct from surrounding bioregions.
The Hispaniola monkey is an extinct primate that was endemic on the island of Hispaniola, in the present-day Dominican Republic. The species is thought to have gone extinct around the 16th century. The exact timing and cause of the extinction are unclear, but it is likely related to the settlement of Hispaniola by Europeans after 1492.
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.
Miocnus is an extinct genus of ground sloths of the family Megalocnidae endemic to Cuba during the Pleistocene and very early Holocene epochs, living from 1.8 Mya—11,000 years ago, existing for approximately 1.789 million years.
The mammalian order Pilosa, which includes the sloths and anteaters, includes various species from the Caribbean region. Many species of sloths are known from the Greater Antilles, all of which became extinct over the last millennia, but some sloths and anteaters survive on islands closer to the mainland.
A unique and diverse albeit phylogenetically restricted mammal fauna is known from the Caribbean region. The region—specifically, all islands in the Caribbean Sea and the Bahamas, Turks and Caicos Islands, and Barbados, which are not in the Caribbean Sea but biogeographically belong to the same Caribbean bioregion—has been home to several families found nowhere else, but much of this diversity is now extinct.
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.
Megalocnidae is an extinct family 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 in body size and lifestyle, with Megalocnus being terrestrial and probably weighing several hundred kilograms, while Neocnus was likely arboreal and similar in weight to extant tree sloths, at less than 10 kilograms.
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 32–79 kilograms (71–174 lb), comparable to a pig.
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.
Ortotherium is a genus of megalonychid ground sloth from the Late Miocene Ituzaingó Formation of Entre Rios Province, Argentina. Although many species were described, the only valid species of the genus is Ortotherium laticurvatum, with many species being junior synonyms. Ortotherium is known from very fragmentary material, all of which is material from the mandible and teeth. The holotype of O. laticurvatum consists of an incomplete left dentary that had been unearthed from a series of sediments known as ‘Conglomerado osifero’ in Paraná, Argentina. Argentina paleontologist Florentino Ameghino named the species in 1885, though he would go on to name four more, invalid, species of the genus. One species however, O. brevirostrum, has been reclassified as Mesopotamocnus.
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