Pilosa

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Piloso
Fossil range: Paleocene - Holocene, 55.8–0 Ma
Giant anteater, Myrmecophaga tridactyla
Giant anteater, Myrmecophaga tridactyla
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Superorder: Xenarthra
Order: Pilosa
Flower, 1883
Suborders

Pilosa is an order of placental, New World mammals that includes the anteaters (suborder Vermilingua) and the sloths (suborder Folivora). Like the armadillos (order Cingulata), also of superorder Xenarthra, pilosans are distinguished from other mammals by the presence of xenarthrales (additional, unique articulations between lumbar vertebrae), a double posterior vena cava vein, a divided womb in females, who also have a common genital and urinary tract. They differ from armadillos in that extant pilosans lack armor and have a lot of hair. They are found today mainly in Central and South America, although their range extends into Mexico and southern United States.


Overview and characteristics

The order Pilosa is a group of placental mammals, extant today only in the Americas. It includes the anteaters and sloths, including the recently extinct ground sloths. The name comes from the Latin word for "hairy".[1]

The biogeographic origins of the Pilosa is still unclear,[2] but they can be traced back in South America as far as the early Paleogene (about 60 million years ago, or only a short time after the end of the dinosaur 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, Pilosa is part of the larger group Xenarthra. 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). It was subsequently realized that Edentata was polyphyletic—that it contained unrelated families and was thus invalid.

Classification

Restoration of the Shasta ground sloth, Nothrotheriops shastensis

Order Pilosa

  • Suborder Vermilingua
    • Family Cyclopedidae
      • Silky anteater, Cyclopes didactylus
    • Family Myrmecophagidae
      • Giant anteater, Myrmecophaga tridactyla
      • Northern tamandua, Tamandua mexicana
      • Southern tamandua, Tamandua tetradactyla
  • Suborder Folivora
    • Family Bradypodidae: three-toed sloths
      • Pygmy three-toed sloth, Bradypus pygmaeus
      • Brown-throated three-toed sloth, Bradypus variegatus
      • Pale-throated three-toed sloth, Bradypus tridactylus
      • Maned three-toed sloth, Bradypus torquatus
    • Family Megalonychidae: two-toed sloths and extinct megalonychid ground sloths
      • Hoffman's two-toed sloth, Choloepus hoffmanni
      • Linnaeus's two-toed sloth, Choloepus didactylus
    • Family †Megatheriidae: megatheriid ground sloths
    • Family †Mylodontidae: mylodontid ground sloths
    • Family †Nothrotheriidae: nothrotheriid ground sloths

References
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Mammals
Monotremata (platypus, echidnas)

Marsupialia: | Paucituberculata (shrew opossums) | Didelphimorphia (opossums) | Microbiotheria | Notoryctemorphia (marsupial moles) | Dasyuromorphia (quolls and dunnarts) | Peramelemorphia (bilbies, bandicoots) | Diprotodontia (kangaroos and relatives)

Placentalia: Cingulata (armadillos) | Pilosa (anteaters, sloths) | Afrosoricida (tenrecs, golden moles) | Macroscelidea (elephant shrews) | Tubulidentata (aardvark) | Hyracoidea (hyraxes) | Proboscidea (elephants) | Sirenia (dugongs, manatees) | Soricomorpha (shrews, moles) | Erinaceomorpha (hedgehogs and relatives) Chiroptera (bats) | Pholidota (pangolins)| Carnivora | Perissodactyla (odd-toed ungulates) | Artiodactyla (even-toed ungulates) | Cetacea (whales, dolphins) | Rodentia (rodents) | Lagomorpha (rabbits and relatives) | Scandentia (treeshrews) | Dermoptera (colugos) | Primates |

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  1. Kidd, D.A. (1973). Collins Latin Gem Dictionary. London: Collins. ISBN 0-00-458641-7. 
  2. A proposed clade, Atlantogenata, would include Xenarthra and early African mammals.