''Acratocnus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...

s that were found on

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

Hispaniola Hispaniola (, also ; es, La Española; Latin and french: Hispaniola; ht, Ispayola; tnq, Ayiti or Quisqueya) is an island in the Caribbean that is part of the Greater Antilles. Hispaniola is the most populous island in the West Indies, and th ...

(today the

Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares wit ...

and

Haiti Haiti (; ht, Ayiti ; French: ), officially the Republic of Haiti (); ) and formerly known as Hayti, is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean Sea, east of Cuba and Jamaica, and ...

), and

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

Classification

Like all of the Antillean sloths, ''Acratocnus'' was formerly thought on the basis of morphological evidence to be a member of the family

Megalonychidae 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 actually one possible find dating ...

, 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, now placed in the family

Megalocnidae 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 ...

Location

Fossils of ''Acratocnus'' were found on the islands of Puerto Rico, Cuba, and Hispaniola, where they inhabited the montane forests of the highlands. The Puerto Rican ground sloth, ''Acratocnus odontrigonus'' is known from several poorly documented cave excavations in northwestern Puerto Rico. The various species are regarded as being semi-arboreal because of their (relatively speaking) small size and their large hooked claws.

Size

The various species of ''Acratocnus'' ranged in weight from , and were thus much larger than living tree sloths (genera '' Choloepus'' and '' Bradypus''), which do not exceed .

Extinction

As with many sloth fossils, these species of sloth have not been radiometrically dated. It is suggested that the Puerto Rican and Hispaniolan ''Acratocnus'' species survived into the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

but disappeared by the mid-

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

. The related Cuban ground sloth, ''

Megalocnus ''Megalocnus'' ("great sloth" in Greek) is a genus of extinct large 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 estimate ...

rodens'', survived until at least c. 6600 BP, and the latest survival reported for any of the Antillean sloths is c. 5000 BP, for the

n ''Neocnus comes'', based on

AMS AMS or Ams may refer to: Organizations Companies * Alenia Marconi Systems * American Management Systems * AMS (Advanced Music Systems) * ams AG, semiconductor manufacturer * AMS Pictures * Auxiliary Medical Services Educational institutions * A ...

radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was dev ...

. The cause(s) of their extinctions may have been climatic changes, or more likely, human hunting by the

indigenous peoples of the Caribbean At the time of first contact between Europe and the Americas, the indigenous peoples of the Caribbean included the Taíno of the northern Lesser Antilles, most of the Greater Antilles and the Bahamas, the Kalinago of the Lesser Antilles, the Ciguay ...

References

{{Taxonbar, from=Q965019 Prehistoric sloths Prehistoric placental genera Pleistocene xenarthrans Pleistocene first appearances Pleistocene extinctions Rancholabrean Pleistocene Caribbean Mammals of the Caribbean Extinct animals of Cuba Extinct animals of the Dominican Republic Extinct animals of Haiti Mammals of the Dominican Republic Mammals of Haiti Mammals of Cuba Fossils of Puerto Rico Fossils of Cuba Fossils of the Caribbean Fossils of the Dominican Republic Mammals of Puerto Rico Fossil taxa described in 1916

Classification

Location

Size

Extinction

See also

References