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The four llamas and two camels are 'camelids': members of the biological family 'Camelidae', the only living family in the suborder 'Tylopoda'.
Camelids are even-toed ungulates: they are classified in the Artiodactyla order. Other suborders of Artiodactyla include pigs, peccaries and hippos (suborder Suina) and the extraordinarily successful and diverse suborder Ruminantia (which includes cattle, goats, antelope and many others).
Camelids tend to be large and are strictly herbivorous. Camelids differ from 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 red blood cells and a special type of antibodies lacking the light chain, besides the normal antibodies found in other species (from this different antibody is being developed the so-called nanobodies) . They have long legs that, because they lack tensor skin to bridge between thigh and body, look longer still. They do not have hooves, rather a two-toed foot with toenails and a soft footpad (Tylopoda is Latin for "padded foot"). The main weight of the animal is borne by these 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 camel species have developed extensive adaptations to fit them to life in harsh, near-waterless environments. Wild populations of the bactrian camel have even adapted to drink brackish water, and some herds live in nuclear test areas.^[1]
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 Vicuñas.

Contents

Scientific classification

Phylogenetic tree

Extinct genera of camelids

References

External links

Scientific classification

★ 'ORDER ARTIODACTYLA'

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★ Suborder Suina

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★ Suborder Ruminantia

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★ 'Suborder Tylopoda'

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★ †Family Xiphodontidae

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★ †Family Protoceratidae

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★ †Family Oromerycidae

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★ 'Family Camelidae'

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★ †Subfamily Poebrodontinae

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★ †Subfamily Poebrotheriinae

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★ †Subfamily Miolabinae

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★ †Subfamily Stenomylidae

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★ †Subfamily Floridatragulinae

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★ Subfamily Camelinae

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★ Genus: ''Lama''

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★ Llama, ''Lama glama''

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★ Guanaco, ''Lama guanicoe''

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★ Genus: ''Vicugna''

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★ Vicuña, ''Vicugna vicugna''

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★ Alpaca, ''Vicugna pacos'' (previously categorized in genus ''Lama'')

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★ Genus: ''Camelus''

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★ Dromedary, ''Camelus dromedarius''

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★ Bactrian Camel, ''Camelus bactrianus''

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★ †Syrian Camel

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★ ''Camelus gigas''

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★ ''Camelus hesternus''

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★ ''Camelus sivalensis''

Phylogenetic tree

Camelid ancestor	North America12-25 mya	Lamini	10.4 mya	6.4 mya	1.4 mya	Llama	South America
						Guanaco
					Vicuna
				Alpaca
		Camelini	8 mya	Bactrian camel			Asia
				Dromedary			Asia, Africa

Extinct genera of camelids

Genus name	Epoch	Remarks
''Aepycamelus''	Miocene	Tall, s-shaped neck. True padded camel feet.
''Camelops''	Pliocene-Pleistocene	Large, with true camel feet. Hump status uncertain.
''Oxydactylus''
''Poebrotherium''
''Procamelus''	Miocene	Ancestor of extinct ''Titanolypus'' and modern ''Camelus''.
''Protylopus''
''Stenomylus''	Miocene-Pleistocene	Miniature, possibly llama-like camelid. Lacked padded "camel foot"; had hooves instead.
''Titanotylopus''	Miocene-Pleistocene	Tall, humped, true camel feet.

The newly discovered giant Syrian Camel is yet to be officially described.

References

1. Wild Bactrian Camels Critically Endangered, Group Says National Geographic, 3 December 2002

External links

★ Pictures of camelid species