Myrmecophagidae
Megalonychidae
Bradypodidae
Dasypodidae
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 realized 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 Dasypodidae: armadillos
- About 20 species in 8 genera, not listed here.
- Family Myrmecophagidae: anteaters
- Silky Anteater, Cyclopes didactylus
- Giant Anteater, Myrmecophaga tridactyla
- Northern Tamandua, Tamandua mexicana
- Southern Tamandua, Tamandua tetradactyla
- Suborder Tardigrada
- 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
- Ground sloth, Megalonyx jeffersonii (extinct)
- Family Megatheriidae (extinct)
- Giant ground sloth, Eremotherium laurillardi
- Family Mylodontidae (extinct)
- Suborder Cingulata (extinct)