Pilosans of the Caribbean

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.

For the purposes of this article, the "Caribbean" includes all islands in the Caribbean Sea (except for small islets close to the mainland) and the Bahamas, Turks and Caicos Islands, and Barbados, which are not in the Caribbean Sea but biogeographically belong to the same Caribbean bioregion.

Overview

Extinct sloths are known from the three Greater Antilles of Cuba, Hispaniola, and Puerto Rico and several smaller Antillean islands, but they are missing from the fourth of the Greater Antilles, Jamaica. These are part of the family Megalonychidae, which also includes some of the extinct giant ground sloths, such as Megalonyx, and the living two-toed sloths (Choloepus) of the American mainland.^[1] All Greater Antillean sloths are now extinct; their extinction by ~4400 BP (uncalibrated radiocarbon date) apparently postdated the extinction of the mainland ground sloths by about six thousand years, and coincided (to within a thousand years) with the arrival of humans on the islands.^[2] The extinct Caribbean sloths apparently had a wide range of locomotor habits corresponding to varying degrees of arboreality, but were generally more terrestrial than extant tree sloths.^[3][4] They had been present on the Antilles since the early Oligocene, 32 million years ago.^[5] The subdivision of Antillean sloths into several subfamilies implies at least a diphyletic origin for them, requiring two or more separate colonization events.^[6]

In addition to the Greater Antillean sloths, some other pilosans are still extant on islands close to the Central and South American mainland. This includes several anteaters and a member of the other sloth family, that of the three-toed sloths, restricted to a small island in Panama.^[7] The record of a tamandua from Cozumel, off Mexico, was probably in error.^[8]

The genera of Caribbean pilosans are classified as follows:^[9]

• Order Pilosa
  • Suborder Folivora (sloths)
    • Family Bradypodidae: Bradypus
    • Family Megalonychidae
      • Subfamily Choloepodinae
        • Tribe Acratocnini: Acratocnus
        • Tribe Cubanocnini: Neocnus
        • Incertae sedis: Paulocnus
      • Subfamily Megalonychinae
        • Tribe Megalocnini: Megalocnus
        • Tribe Mesocnini: Mesocnus
      • Subfamily Ortotheriinae: Paramiocnus
      • Incertae sedis: Imagocnus, Galerocnus, several unidentified genera
  • Suborder Vermilingua (anteaters)
    • Family Cyclopedidae: Cyclopes
    • Family Myrmecophagidae: Tamandua

Cuba

Cuba is the largest of the Greater Antilles. A diverse assortment of sloths is known.

• Acratocnus antillensis (previously Miocnus antillensis), a sloth known exclusively from Cuba. Isolated femora referred to separate species Habanocnus hoffstetteri and H. paulacoutoi fall within the range of variation of this species.^[10]
• Galerocnus jaimezi, a sloth.^[11]
• Imagocnus zazae, a large sloth from the early Miocene fauna of Domo de Zaza. Although it is recognizably megalonychid, its precise relations are obscure. A large pelvis found at Domo de Zaza may indicate the presence of another, even larger sloth; alternatively, I. zazae may have been variable in size.^[12]
• Neocnus gliriformis (previously Microcnus gliriformis), a sloth found only on Cuba.^[13]
• Megalocnus rodens, a common sloth in faunas from western and central Cuba.^[14] It has been radiocarbon-dated to about 6000 years before present.^[15]
• Neocnus major, also known from Cuba alone. It includes the previously recognized N. minor and N. baireiensis and may not itself be distinct from N. gliriformis.^[16]
• Paramiocnus riveroi, a large and possibly arboreal sloth known from limited remains.^[17]
• Parocnus browni (previously Mesocnus browni), a sloth related to Hispaniolan P. serus. The previously recognized species Mesocnus torrei and Mesocnus herrerai are now regarded as identical to P. browni.^[18] Remains of P. browni have been radiocarbon-dated to about 5000 years before present.^[15]

Hispaniola

Hispaniola, the second largest of the Greater Antilles, is divided into Haiti and the Dominican Republic. It has a diverse sloth fauna.

• Acratocnus simorhynchus, a sloth from eastern Hispaniola known from remains dated to about 20,000 years before present.^[19]
• Acratocnus ye, a sloth known only from Hispaniola.^[20]
• Megalocnus zile, a sloth known from both Hispaniola and the satellite island of Tortuga, apparently much rarer than its Cuban relative M. rodens.^[21]
• Neocnus comes (previously Acratocnus comes and Synocnus comes), a large Neocnus commonly found in cave deposits throughout Hispaniola.^[22] Several remains have been radiocarbon-dated, the youngest to about 5,000 years before present.^[23]
• Neocnus dousman, a medium-sized Neocnus found throughout Hispaniola.^[24] A single radiocarbon-dated specimen is about 10,000 years old.^[23]
• Neocnus toupiti, a small Neocnus and perhaps the smallest sloth known, found in Haiti.^[25]
• Parocnus serus, a sloth known from Hispaniola and the satellite islands of Tortuga and Gonâve.^[26] A specimen has been radiocarbon-dated to over 14,000 years before present.^[23]

Tortuga

Tortuga is an island off northern Haiti.

• Megalocnus zile, a sloth known also from mainland Hispaniola.^[21]
• Parocnus serus, a sloth found also on mainland Hispaniola and Gonâve.^[26]

Gonâve

Gonâve is an island off southwestern Haiti.

• Parocnus serus, a sloth also known from mainland Hispaniola and Tortuga.^[26]

Puerto Rico

Only one sloth is known from the Quaternary of Puerto Rico, the easternmost of the Greater Antilles; another species is known from much older, Oligocene, sediments.

• Acratocnus odontrigonus, a sloth known only from Puerto Rico. Acratocnus major, described on the basis of somewhat larger Puerto Rican sloth bones, simply represents large individuals of A. odontrigonus.^[27]
• A small sloth femur has been found at an early Oligocene site in southwestern Puerto Rico. It is not sufficiently diagnostic to permit conclusive identification as a megalonychid.^[28]

Grenada

Grenada is the southernmost island of the main Lesser Antillean island arc.

• Three teeth of a sloth have been found in a late Pliocene or early Pleistocene deposit that also yielded the capybara Hydrochoerus gaylordi. The teeth differ in size and may represent either one or two species and although recognizably megalonychid, their precise relationships cannot be determined.^[29]

Trinidad

Trinidad is a large island off northeastern Venezuela. It hosts two species of anteaters that are also found on mainland South America.

• Cyclopes didactylus, the pygmy anteater, also known from Mexico to Brazil.^[30]
• Tamandua tetradactyla, the southern tamandua, also known across South America east of the Andes.^[31]

Curaçao

Curaçao is a Dutch island off northwestern Venezuela.

• Paulocnus petrifactus, a medium-sized sloth that may be related to Antillean Acratocnus.^[32]

Escudo de Veraguas

Escudo de Veraguas is an island off northern Panama. Despite its small size, it supports two mammal species found nowhere else: the bat Artibeus incomitatus and the only extant Caribbean sloth.^[33]

• Bradypus pygmaeus, a critically endangered small sloth related to mainland B. variegatus.^[33]

Related articles

• List of extinct late Pleistocene North American Pilosans
• List of extant Central American Pilosans
• List of extant South American Pilosans

References

Literature cited

• Anderson, R.P. and Handley, C.O., Jr. 2001. A new species of three-toed sloth (Mammalia: Xenarthra) from Panama, with a review of the genus Bradypus. Proceedings of the Biological Society of Washington 114:1–33.
• Arredondo, C. and Arredondo, O. 2000. Nuevo genero y especie de perezoso (Edentata: Megalonychidae) del Pleistoceno de Cuba. Revista Biologia 14(1):66–72.
• Arredondo, C. and Rivero, M. 1997. Nuevo genero y especie de Megalonychidae del Cuaternario Cubano. Revista Biologia 11:105–112.
• Gardner, A.L. 2005. Order Pilosa. Pp. 100–103 in Wilson, D.E. and Reeder, D.M. (eds.). Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp. ISBN 978-0-8018-8221-0
• Jones, J.K., Jr., and Lawlor, T.E. 1965. Mammals from Isla Cozumel, México, with description of a new species of harvest mouse. University of Kansas Publications, Museum of Natural History 16:409–419.
• Koopman, K.F. 1959. The zoogeographical limits of the West Indies. Journal of Mammalogy 40(2):236–240.
• MacPhee, R.D.E., Singer, R. and Diamond, M. 2000. Late Cenozoic land mammals from Grenada, Lesser Antillean island-arc. American Museum Novitates 3302:1–20.
• Rega, E., McFarlane, D.A., Lundberg, J. and Christenson, K. 2002. A new megalonychid sloth from the Late Wisconsinan of the Dominican Republic. Caribbean Journal of Science 38(1–2):11–19.
• Steadman, D.W.; Martin, P.S.; MacPhee, R.D.E.; Jull, A.J.T.; McDonald, H.G.; Woods, C.A.; Iturralde-Vinent, M.; Hodgins, G.W.L. (2005). "Asynchronous extinction of late Quaternary sloths on continents and islands". Proceedings of the National Academy of Sciences. 102 (33): 11763–11768. doi:10.1073/pnas.0502777102. PMC 1187974. PMID 16085711. 
• White, J. L. 1993. Indicators of Locomotor Habits in Xenarthrans: Evidence for Locomotor Heterogeneity Among Fossil Sloths. Journal of Vertebrate Paleontology 13: 230-242.
• White, J.L. and MacPhee, R.D.E. 2001. The sloths of the West Indies: A systematic and phylogenetic review. Pp. 201–236 in Woods, C.A. and Sergile, F.E. (eds.). Biogeography of the West Indies: patterns and perspectives. CRC Press, Boca Raton, Florida. ISBN 0-8493-2001-1