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Temporal range: Paleocene - Holocene, 55.8–0 Ma
Pilosa collage.png
Pilosa species of different families; from top-left, clockwise: Silky anteater (Cyclopes didactylus), giant anteater (Myrmecophaga tridactyla), pale-throated sloth (Bradypus tridactylus), Linnaeus's two-toed sloth (Choloepus didactylus)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Superorder: Xenarthra
Order: Pilosa
Flower 1883

The order Pilosa /pˈlsə/ is a group of placental mammals, extant today only in the Americas. It includes the anteaters and sloths, including the extinct ground sloths, which became extinct about 10,000 years ago. The name comes from the Latin word for "hairy".[2] Pilosans are good examples of ecological harmony. Anteaters, for example, feed lightly and for a short time at any one ant nest, allowing the colony to regrow easily. Also, sloths' fur is home to many insects, as well as a type of alga that helps camouflage the sloths.[3]

Origins and taxonomy[edit]

The biogeographic origins of the Pilosa are still unclear,[4] but they can be traced back in South America as far as the early Paleogene (about 60 million years ago, only a short time after the end of the Mesozoic Era). The presence of these animals in Central America and their former presence in North America is a result of the Great American Interchange. A number of sloths were also formerly present on the Antilles, which they reached from South America by some combination of rafting or floating with the prevailing currents.

Together with the armadillos, which are in the order Cingulata, pilosans are part of the larger superorder Xenarthra, a defining characteristic of which is the presence of xenarthrals (extra formations between lumbar vertebrae). In the past, Pilosa was regarded as a suborder of the order Xenarthra, while some more recent classifications regard Pilosa as an order within the superorder Xenarthra. Earlier still, both armadillos and pilosans were classified together with pangolins and the aardvark as the order Edentata (meaning toothless, because the members do not have front incisor teeth or molars, or have poorly developed molars). Edentata was subsequently realized to be polyphyletic; it contained unrelated families and was thus invalid.



Restoration of the Shasta ground sloth, Nothrotheriops shastensis

Order Pilosa


Major families within Pilosa[5]















Cladogram of living Pilosa[5][6][7]


Myrmecophaga tridactyla


T. mexicana

T. tetradactyla


C. rufus

C. thomasi

C. ida

C. xinguensis

C. dorsalis

C. didactylus


C. didactylus

C. hoffmanni


B. torquatus

B. pygmaeus

B. tridactylus

B. variegatus


  1. ^ Gardner, A.L. (2005). "Order Pilosa". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 100–103. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ Kidd, D.A. (1973). Collins Latin Gem Dictionary. London: Collins. p. 248. ISBN 0-00-458641-7.
  3. ^ George A. Feldhamer; Lee C. Drickamer; Stephen H. Vessey; Joseph F. Merritt; Carey Krajewski (1 January 2015). Mammalogy: Adaptation, Diversity, Ecology. JHU Press. pp. 343–. ISBN 978-1-4214-1588-8.
  4. ^ A proposed clade, Atlantogenata, would include Xenarthra and early African mammals.
  5. ^ a b c Presslee, S.; Slater, G. J.; Pujos, F.; Forasiepi, A. M.; Fischer, R.; Molloy, K.; Mackie, M.; Olsen, J. V.; Kramarz, A.; Taglioretti, M.; Scaglia, F.; Lezcano, M.; Lanata, J. L.; Southon, J.; Feranec, R.; Bloch, J.; Hajduk, A.; Martin, F. M.; Gismondi, R. S.; Reguero, M.; de Muizon, C.; Greenwood, A.; Chait, B. T.; Penkman, K.; Collins, M.; MacPhee, R.D.E. (2019). "Palaeoproteomics resolves sloth relationships" (PDF). Nature Ecology & Evolution. 3 (7): 1121–1130. doi:10.1038/s41559-019-0909-z. PMID 31171860. S2CID 174813630.
  6. ^ Miranda, Flávia R.; Casali, Daniel M.; Perini, Fernando A.; Machado, Fabio A.; Santos, Fabrício R. (2018). "Taxonomic review of the genus Cyclopes Gray, 1821 (Xenarthra: Pilosa), with the revalidation and description of new species". Zoological Journal of the Linnean Society. 183 (3): 687–721. doi:10.1093/zoolinnean/zlx079.
  7. ^ Gibb, Gillian C.; Condamine, Fabien L.; Kuch, Melanie; Enk, Jacob; Moraes-Barros, Nadia; Superina, Mariella; Poinar, Hendrik N.; Delsuc, Frédéric (2015). "Shotgun Mitogenomics Provides a Reference PhyloGenetic Framework and Timescale for Living Xenarthrans". Molecular Biology and Evolution. 33 (3): 621–42. doi:10.1093/molbev/msv250. PMC 4760074. PMID 26556496.