| 词条 | Acratocnus |
| 释义 |
| name = Acratocnus | image = | image_caption = A. antillensis | fossil_range = Late Pleistocene (Rancholabrean) ~{{fossil range|0.126|0.011}} | regnum = Animalia | phylum = Chordata | classis = Mammalia | superordo = Xenarthra | ordo = Pilosa | familia = Megalonychidae | genus = †Acratocnus | genus_authority = Anthony 1916 | type_species = Acratocnus odontrigonus | type_species_authority = Anthony 1916 | subdivision_ranks = Species | subdivision =
}} Acratocnus is an extinct genus of ground sloth found in Cuba, Hispaniola and Puerto Rico. ClassificationLike all of the Antillean sloths, Acratocnus is a member of the family Megalonychidae, whose sole surviving genus is Choloepus, representing the two-toed tree sloths. LocationFossils 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. SizeThe various species of Acratocnus ranged in weight from {{convert|50|to|150|lb|kg}}, and were thus much larger than living tree sloths (genera Choloepus and Bradypus), which do not exceed {{convert|20|lb|kg}}.{{Citation needed|date=May 2014}} ExtinctionAs with many sloth fossils, these species of sloth have not been radiometrically dated.[1] It is suggested{{by whom|date=March 2019}} that the Puerto Rican and Hispaniolan Acratocnus species survived into the late Pleistocene but disappeared by the mid-Holocene.{{cn|date=March 2019}} The related Cuban ground sloth, Megalocnus rodens, survived until at least c. 6600 BP,[2] and the latest survival reported for any of the Antillean sloths is c. 5000 BP, for the Hispaniolan Neocnus comes,[2] based on AMS radiocarbon dating. The cause(s) of their extinctions may have been climatic changes, or more likely, human hunting.[2] See also{{portal|Paleontology|Prehistoric mammals|Prehistory of North America}}
References1. ^http://academic.uprm.edu/publications/cjs/Vol35b/35_238-248.pdf{{dead link|date=October 2016 |bot=InternetArchiveBot |fix-attempted=yes }} {{Taxonbar|from=Q965019}}2. ^1 2 {{cite journal | last = Steadman | first = D. W. |author2=Martin, P. S. |author3=MacPhee, R. D. E. |author4=Jull, A. J. T. |author5=McDonald, H. G. |author6=Woods, C. A. |author7=Iturralde-Vinent, M. |author8=Hodgins, G. W. L. | author1link = David Steadman | author2link = Paul S. Martin | title = Asynchronous extinction of late Quaternary sloths on continents and islands | journal = Proc. Natl. Acad. Sci. USA | volume = 102 | issue = 33 | pages = 11763–11768 | publisher = National Academy of Sciences | date = 2005-08-16 | url = http://www.pnas.org/content/102/33/11763.abstract | doi = 10.1073/pnas.0502777102 | accessdate = 2009-01-24 | pmid = 16085711 | pmc = 1187974}} 11 : Prehistoric sloths|Prehistoric mammal genera|Pleistocene xenarthrans|Pleistocene first appearances|Pleistocene extinctions|Rancholabrean|Pleistocene Caribbean|Fossils of Cuba|Fossils of the Caribbean|Fossils of the Dominican Republic|Fossil taxa described in 1916 |
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