The Xenarthrans: Armadillos, Glyptodonts, Anteaters, and Sloths

Abstract

From the time that the first xenarthrans appeared as early armadillos in the Early Paleocene Itaborai, the group diversified into strange and wonderful forms. Besides the Dasypodidae, a group called the Glyptodontidae arose and diversified; some were the size (and shape) of a Volkswagen bug and were harmless grazers. They were very common on the grassy savannas of South America. Also, the sloth lineage appeared with the last species reaching the greatest size of any southern mammal. Megatherium americanum became one of the largest mammals known in South America, equivalent in size to an elephant. Finally a short history of the little-known anteaters is presented. A discussion of the possible but unconfirmed origins of the xenarthra is suggested, and the group is presented as one of the most ancient lineages of modern mammals and native South Americans.