Pilosa

Pilosa Temporal range: Paleocene - Holocene, 55.8–0 Ma PreЄ Є O S D C P T J K Pg N
Giant anteater, Myrmecophaga tridactyla
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Superorder:	Xenarthra
Order:	Pilosa Flower, 1883
Suborders
Vermilingua - anteaters Folivora - sloths

The order Pilosa is a group of placental mammals, extant today only in the Americas. It includes the anteaters and sloths, including the extinct ground sloths, which went extinct about 20,000 years ago. The name comes from the Latin word for "hairy". 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 algae that helps camouflage the sloths.

Origins and taxonomy

The biogeographic origins of the Pilosa are still unclear, 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 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, 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.

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