Taxonomy and Phylogeny
The giant anteater got its binomial name from Carl Linnaeus in 1758. Its generic name, Myrmecophaga, and specific name, tridactyla, are both Greek, meaning "anteater" and "three fingers" respectively. Three subspecies have been tentatively proposed: M. t. tridactyla (ranging from Venezuela and the Guianas to northern Argentina), M. t. centralis (native to Central America, northwestern Colombia and northern Ecuador), and M. t. artata (native to northeastern Columbia and northwestern Venezuela). The giant anteater is grouped with the semi-arboreal northern and southern tamandua in the family Myrmecophagidae. Together with the family Cyclopedidae, whose only extant member is the arboreal silky anteater, the two families comprise the suborder Vermilingua.
Anteaters and sloths belong to order Pilosa and share superorder Xenarthra with armadillos (Cingulata). Xenarthra split 65 million years ago (MYA) during the Late Cretaceous epoch. Anteaters and sloths diverged around 55 MYA, between the Paleocene and Eocene epochs. The Cyclopes lineage emerged around 30 MYA in the Oligocene epoch, while the Myrmecophaga and Tamandua lineages split 10 MYA in the Late Miocene sub-epoch.
The fossil record for anteaters is generally sparse. Some known fossils include the Pliocene genus Palaeomyrmidon, a close relative to the silky anteater, Protamandua, the sister taxon to the clade that includes the giant anteater and the tamanduas from the Miocene, and Neotamandua, a sister taxon to Myrmecophaga. Protamandua was larger than the silky anteater but smaller than a tamandua, while Neotamandua was larger, falling somewhere between a tamandua and a giant anteater. Protamandua did not appear to have feet specialized for terrestrial or arboreal locomotion but it may have had a prehensile tail. Neotamandua, on the other hand, is unlikely to have had a prehensile tail and its feet were intermediate in form between those of the tamanduas and the giant anteater. The species Neotamandua borealis was suggested to be an ancestor of the latter.
The giant anteater is the most terrestrial of the living anteater species. Anteaters may originally have been adapted to arboreal life and the evolution of the giant anteater may have been aided by the expansion of open habitats such as savanna in South America and the availability of insects living in colonies there, such as termites, that provided a larger feeding target. Both the giant anteater and the southern tamandua are well represented in the fossil record of the late Pleistocene and early Holocene.
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