Camelidae

Camelidae Temporal range:MiddleEocene–Holocene
ABactrian camelwalking in snow
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Suborder:	Tylopoda
Superfamily:	Cameloidea
Family:	Camelidae Gray,1821
Type genus
Camelus
Subfamilies
†Poebrodontinae †Poebrotheriinae †Miolabinae †Stenomylinae †Floridatragulinae Camelinae
Current range of camelids, all species

Camelidsare members of the biologicalfamilyCamelidae,the only currently living family in the suborderTylopoda.The sevenextantmembers of this group are:dromedary camels,Bactrian camels,wild Bactrian camels,llamas,alpacas,vicuñas,andguanacos.Camelids areeven-toed ungulatesclassified in theorderArtiodactyla,along with species includingwhales,pigs,deer,cattle,andantelopes.

Characteristics

Camelid feet lack functional hooves, with the toe bones being embedded in a broad, cutaneous pad.

Camelids are large, strictlyherbivorousanimals with slender necks and long legs. They differ fromruminantsin a number of ways.Their dentition show traces of vestigial centralincisorsin theincisive bone,and the third incisors have developed into canine-like tusks. Camelids also have truecanine teethand tusk-likepremolars,which are separated from themolarsby a gap. As in ruminants, the upper incisors are largely absent and are replaced by adental padconsisting of connective tissue covered withepithelium.The musculature of the hind limbs differs from those of other ungulates in that the legs are attached to the body only at the top of the thigh, rather than attached by skin and muscle from the knee upwards. Because of this, camelids have to lie down by resting on their knees with their legs tucked underneath their bodies.They have three-chamberedstomachs,rather than four-chambered ones; their upper lips are split in two, with each part separately mobile; and, uniquely among mammals, theirred blood cellsare elliptical.They also have a unique type ofantibodies,which lack the light chain, in addition to the normal antibodies found in other mammals. These so-calledheavy-chain antibodiesare being used to developsingle-domain antibodieswith potentialpharmaceuticalapplications.

Camelids do not have hooves; rather, they have two-toed feet with toenails and soft foot pads (Tylopodais Greek for "padded foot" ). Most of the weight of the animal rests on these tough, leathery sole pads. The South American camelids have adapted to the steep and rocky terrain by adjusting the pads on their toes to maintain grip.The surface area of Camels foot pads can increase with increasing velocity in order to reduce pressure on the feet and larger members of the camelid species will usually have larger pad area, which helps to distribute weight across the foot.Many fossil camelids wereunguligradeand probably hooved, in contrast to all living species.

Camelids are behaviorally similar in many ways, including their walking gait, in which both legs on the same side are moved simultaneously. While running, camelids engage a unique "running pace gait" in which limbs on the same side move in the same pattern they walk, with both left legs moving and then both right, which ensures that the fore and hind limb will not collide while in fast motion. During this motion, all four limbs momentarily are off the ground at the same time.Consequently, camelids large enough for human beings to ride have a typical swaying motion.

Dromedary camels, bactrian camels, llamas, and alpacas are allinduced ovulators.

The three Afro-Asian camel species have developed extensive adaptations to their lives in harsh, near-waterless environments. Wild populations of the Bactrian camel are even able to drinkbrackish water,and some herds live in nuclear test areas.

Comparative table of the seven extant species in the family Camelidae:

Species	Image	Natural range	Weight
Camelus
Bactrian camel (Camelus bactrianus)		CentralandInner Asia (entirely domesticated)	300 to 1,000 kg (660 to 2,200 lb)
Dromedary or Arabian camel (Camelus dromedarius)		South Asia and Middle East (entirely domesticated)	300 to 600 kg (660 to 1,320 lb)
Wild Bactrian camel (Camelus ferus)		China and Mongolia	300 to 820 kg (660 to 1,800 lb)
Lama
Llama (Lama glama)		(domestic form of guanaco)	130 to 200 kg (290 to 440 lb)
Guanaco (Lama guanicoe)		South America	about 90 to 120 kg (200 to 260 lb)
Alpaca (Lama pacos)		(domestic form of vicuña)	48 to 84 kg (106 to 185 lb)
Vicuña (Lama vicugna)		South AmericanAndes	35 to 65 kg (77 to 143 lb)

Evolution

Camelid Lamini Lama L. glama L. guanicoe V. vicugna V. pacos Camelini Camelus C. bactrianus C. dromedarius †Camelops ⊞ C. kansanus C. hesternus C. minodokae ⊟

A family tree indicating different species within the Camelidae family

Adymaxion mapof the biogeographic distribution of Camelidae species:

Tertiary distribution

Present-day distributions

Introduced (feral) distributions

The yellow dot is the origin of the family Camelidae and the black arrows are the historic migration routes that explain the present-day distribution.

Camelids are unusual in that their modern distribution is almost the inverse of their area of origin. Camelids first appeared very early in the evolution of the even-toed ungulates, around 50 to 40 million years ago during the middleEocene,in present-day North America. Among the earliest camelids was the rabbit-sizedProtylopus,which still had four toes on each foot. By the lateEocene,around 35 million years ago, camelids such asPoebrotheriumhad lost the two lateral toes, and were about the size of a moderngoat.

The family diversified and prospered, with the two living tribes, theCameliniandLamini,diverging in the late earlyMiocene,about 17 million years ago, but remained restricted to North America until about 6 million years ago, whenParacameluscrossed theBering land bridgeintoEurasia,giving rise to the modern camels, and about 3-2 million years ago, whenHemiaucheniaemigrated into South America (as part of theGreat American Interchange), giving rise to the modern llamas.A population ofParacameluscontinued living in North America and evolved into thehigh arctic camel,which survived until the middle Pleistocene.

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 theearliest human settlers,and possibly as a result of changing environmental conditions after the last ice age, or a combination of these factors. Three species groups survived - thedromedaryof northern Africa and southwest Asia; theBactrian camelof central 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,andvicuñas.Camelids were domesticated by early Andean peoples,and remain in use today.

Fossil camelids show a wider variety than their modern counterparts. One North American genus,Titanotylopus,stood 3.5 m at the shoulder, compared with about 2.0 m for the largest modern camelids. Other extinct camelids included small, gazelle-like animals, such asStenomylus.Finally, a number of very tall, giraffe-like camelids were adapted to feeding on leaves from high trees, including such genera asAepycamelusandOxydactylus.

Whether the wild Bactrian camel (Camelus ferus) is a distinct species or a subspecies (C. bactrianus ferus) is still debated.The divergence date is 0.7 million years ago, long before the start of domestication.

Scientific classification

Adromedarycamel (C. dromedarius) in theAustralianoutback,nearSilverton, New South Wales

South American vicuña (Vicugna vicugna)

Family Camelidae

• †SubfamilyPoebrotheriinae
• †SubfamilyMiolabinae
• †SubfamilyStenomylinae
• †SubfamilyFloridatragulinae
• SubfamilyCamelinae
  • TribeLamini
    • Genus:Lama
      • Llama,Lama glama
      • Guanaco,Lama guanicoe
      • Alpaca,Lama pacos
      • Vicuña,Lama vicugna
    • Genus:Hemiauchenia
      • †Hemiauchenia macrocephala
      • †Hemiauchenia minima
      • †Hemiauchenia blancoensis
      • †Hemiauchenia vera
      • †Hemiauchenia paradoxa
    • GenusPalaeolama
      • †Palaeolama mirifica
  • TribeCamelini
    • Genus:Camelus
      • Bactrian camel,Camelus bactrianus
      • Dromedary,Camelus dromedarius
      • Wild Bactrian camel,Camelus ferus
      • †Syrian camel,Camelus moreli
      • †Camelus sivalensis
      • †Camelus knoblochi
    • Genus:Camelops
      • †Camelops hesternus
    • Genus:Paracamelus
      • †Paracamelus gigas

Phylogeny

Camelid ancestor	Hemiauchenia Lama guanicoe Lama glama Lama pacos Lama vicugna Lama (10.3 to 0.012 mya) Palaeolama (1.8 to 0.012 mya) Blancocamelus (1.8 to 0.3 mya) Pleiolama (10.3 to 2.588 mya) Lamini Camelops (2.588 to 0.012 mya) Paracamelus Bactrian camel Dromedary Camelus (11.608 to 0.781 mya) Procamelus (15.97 to 5.332 mya) Camelini Hesperocamelus (20.43 to 15.97 mya)

Endemic to South America

Endemic to North and South America

Endemic to North America

Endemic to Asia

Endemic to Asia and Africa

Extinct genera

Genus name	Epoch	Remarks
Aepycamelus	Miocene	Tall, s-shaped neck, true padded camel feet
Aguascalientia	EarliestMiocene	A small, primitive, narrow-snouted floridatraguline camel from Mexico, Texas, and Panama
Camelops	Pliocene-Pleistocene	Large, with true camel feet and hump. Status uncertain
Eulamaops	Pleistocene	FromSouth America
Floridatragulus	EarlyMiocene	An unusual species of camel with a long snout
Hemiauchenia	Miocene-Pleistocene	A North and South American lamine genus
Megatylopus	Miocene-EarlyPleistocene	Large camelid fromNorth America
Megacamelus	Miocene-Pleistocene	The largest species of camelid
Michenia	Early-MiddleMiocene	A cameline that existed for 10 million years in North America
Oxydactylus	EarlyMiocene	The earliest member of the "giraffe camel" family
Palaeolama	Pleistocene	A North and South American lamine genus
Poebrotherium	Oligocene	This species of camel took the place of deer and antelope in the White RiverBadlands.
Procamelus	Miocene	Ancestor of extinctTitanolypusand modernCamelus
Protylopus	LateEocene	Earliest member of the camelids
Stenomylus	EarlyMiocene	Small, gazelle-like camel that lived in large herds on the Great Plains
Stevenscamelus	LateEocene	Long-snouted primitive relative ofFloridatragulus
Titanotylopus	Miocene-Pleistocene	Tall, humped, true camel feet

International Year of Camelids

In October 2017 theUnited Nationsdeclared 2024 to be theInternational Yearof Camelids in order to show how camelids are important for food security, economics and culture for manypastoralcommunities.

External links

• Pictures of camelid species