Edentate
Myrmecophagidae
Megalonychidae
Bradypodidae
Dasypodidae
</table>
The order
Xenarthra is a group of placental
mammals, extant today only in the Americas. The origins of the order can be traced back as far as the early
Tertiary (about 60 million years ago, or only a short time after the end of the
dinosaur era).
It includes the
anteaters,
sloths, and
armadillos. In the past, these families were classified together with the
pangolins and
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 realised that Edentata was
polyphyletic—that it contained unrelated
families and was thus invalid. Aardvarks and pangolins are now placed in individual orders, and the new order Xenarthra was erected to group the remaining families (which
are all related). The name
Xenarthra means "strange joints", and was chosen because their
vertebral joints are unlike those of any other mammals.
- ORDER XENARTHRA
- Family Myrmecophagidae: anteaters
- Silky Anteater, Cyclopes didactylus
- Giant Anteater, Myrmecophaga tridactyla
- Northern Tamandua, Tamandua mexicana
- Southern Tamandua, Tamandua tetradactyla
- Family Bradypodidae: three toed sloths
- 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
- Hoffman's Two-toed Sloth, Choloepus hoffmanni
- Southern Two-toed Sloth, Choloepus didactylus
- Family Dasypodidae: armadillos
- About 20 species in 8 genera, not listed here.
