camelid

Camelids

:	Animalia
:	Chordata
:	Mammalia
:	Artiodactyla
:	Camelidae

Species

Lama glama
Lama pacos
Lama guanicoe
Vicugna vicugna
Camelus dromedarius
Camelus bactrianus

The four llamas and two camels are camelids: members of the biological family Camelidae, the only family in the suborder Tylopoda. Camelids are even-toed ungulates: they are classified in the same order as the pigs, peccaries and hippos (suborder Suidae) and the extraordinarily successful and diverse suborder Ruminantia (which includes cattle, goats, antelope and many others). Like many of the Ruminantia, camelids tend to be large and strictly herbivorous. Camelids differ from other ruminants in several ways. They have a three-chambered rather than a four-chambered digestive tract; an upper lip that is split in two with each part separately mobile; an isolated incisor in the upper jaw; and uniquely among mammals, elliptical blood corpuscles (erythrocytes). They have long legs that, because they lack tensor skin to bridge between thigh and body, look longer still, and although they have hooves, only the front part of the hoof touches the ground and the main weight of the animal is borne by the tough, leathery sole-pads. The South American camelids, adapted to steep and rocky terrain, can move the pads on their toes to maintain grip. The two Afro-Asian species have developed extensive adaptations to fit them to life in harsh, near-waterless environments. Camelids are unusual in that their modern distribution is almost a mirror-image of their origin. Camelids first appeared very early in the evolution of the even-toed ungulates, around 45 million years ago during the late Eocene, in present-day North America. The family diversified and prospered but remained confined to the North American continent until only about 2 or 3 million years ago, when representatives arrived in Asia, and (after the formation of the Isthmus of Panama) South America. The original camelids of North America remained common until the quite recent geological past, but then disappeared, possibly as a result of hunting or habitat alterations by the earliest human settlers. Three species groups survived: the Dromedary of northern Africa and south-west Asia; the Bactrian Camel of eastern Asia; and the South American group, which has now diverged into a range of forms that are closely related but usually classified as four species: Llamas, Alpacas, Guanacos, and Vicunas.