The superorder Xenarthra is a group of placental mammals (infraclass Eutheria), 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, shortly after the Mesozoic era). The presence of these animals in Central and North America is explained by the Great American Interchange.
Xenarthrans have the lowest metabolic rates among the therians.
Xenarthra includes the anteat...
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The superorder Xenarthra is a group of placental mammals (infraclass Eutheria), 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, shortly after the Mesozoic era). The presence of these animals in Central and North America is explained by the Great American Interchange.
Xenarthrans have the lowest metabolic rates among the therians.
Xenarthra includes the anteaters, tree sloths, and armadillos, as well as the extinct ground sloths, glyptodonts and pampatheres. In the past, these families were classified together with the pangolins and aardvarks 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 by cladistic standards. Aardvarks and pangolins are now placed in individual orders, and the new order...
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