Lama (genus) - Classification

Classification

Although they were often compared to sheep by early writers, their affinity to the camel was soon perceived. They were included in the genus Camelus in the Systema Naturae of Linnaeus. In 1800, Cuvier moved the llama, alpaca and guanaco to the genus Lama, and the vicuña to the genus Vicugna. Later, the alpaca was transferred to Vicugna. These camelids are, with the two species of true camels, the sole extant representatives of a distinct section of Artiodactyla (even-toed ungulates) called Tylopoda, or "hump-footed," from the peculiar bumps on the soles of their feet. This section consists of a single family, Camelidae, the other sections of the same great division being the Suina or pigs, the Tragulina or chevrotains, and the Pecora or true ruminants, to each of which the Tylopoda have some affinity, standing in some respects in a central position between them, borrowing some characters from each, but showing special modifications not found in any of the others.

Discovery of the extinct fauna of the American continent of the Tertiary period, starting with the 19th century palaeontologists Leidy, Cope, and Marsh, has revealed the early history of this family. Llamas were not always confined to South America; their remains are abundant in the Pleistocene deposits of the Rocky Mountains region, and in Central America; some of these extinct forms were much larger than any now living.

None of these transitional forms have been found in Old World strata; North America was the original home of the Tylopoda. Camelids invaded the Old World via Beringia, and South America via the Isthmus of Panama, as part of the Great American Interchange. The Old World forms were gradually driven southward, perhaps by changes of climate, and having become isolated, they have undergone further special modifications. Meanwhile, the New World members of the family became restricted to South America following the peopling of the Americas by Paleo-Indians and the accompanying extinction of the megafauna.