Macrauchenia was a long-necked, long-limbed, three-toed South American hoofed mammal belonging to the order Litopterna. Macrauchenia probably arose from Theosodon or Promacrauchenia. The oldest fossils date from the Miocene, about 7 million years ago. Macrauchenia survived the Great American Interchange, when the establishment of the Central American land bridge allowed North American mammals to compete with South American species. M. patachonica became extinct in the late Pleistocene, about 20,000-10,000 years ago at the End of the Lujanian  at the time when humans reached South America. It was the last surviving species of litoptern. Charles Darwin discovered the original specimen of M. patachonica during the voyage of the Beagle.
Macrauchenia resembled a humpless camel with sturdy legs, a long neck and a relatively small head. Its feet closely resembled those of a rhinoceros with three hoofs each. It had a body length of around 3 metres (9.8 ft) weighed up to 1042 kg.
The nasal openings were on top of the head, so some early scientists thought it used its nostrils as a form of snorkel. An alternative theory is that the animal had a trunk, perhaps to keep dust out of the nostrils[1,3], as in the saiga antelope.
The ankle joints and shin bones may indicate that the animal had very good mobility, being able to rapidly change direction when it ran at high speed.
Macrauchenia is known, like its relative, Theosodon, to have had a full set of 44 teeth.
Diet and behavior
Tooth of Macrauchenia patachonicaMacrauchenia was an herbivore, likely living on leaves from trees or grasses. Carbon isotope analysis of M. patachonica's tooth enamel, as well as analysis of its hypsodonty index (low in this case; i.e., it was brachydont), body size and relative muzzle width suggests that it was a mixed feeder, combining browsing on C3 foliage with grazing on C4 grasses. Scientists believe that, because of the forms of its teeth, Macrauchenia ate using its trunk to grasp leaves and other food. It is also believed that it lived in herds like modern-day wildebeest or antelope, the better to escape predators.
When Macrauchenia first arose, it would have been preyed upon by the largest of native South American predators, terror birds such as Andalgalornis, and carnivorous sparassodontids such as Thylacosmilus. During the late Pliocene/Early Pleistocene, the Panama Isthmus formed, allowing predators of North American origin, such as the puma, the jaguar and the saber-toothed cat, Smilodon populator, to emigrate into South America and replace the native forms.
It is presumed that Macrauchenia dealt with its predators primarily by outrunning them, or, failing that, kicking them with its long, powerful legs, much like modern-day vicuña or camels. Its potential ability to twist and turn at high speed could have enabled it to evade pursuers.
Restoration of M. patachonica by Robert Bruce HorsfallMacrauchenia was first discovered on 9 February 1834 at Port St Julian in Patagonia (Argentina) by Charles Darwin, when HMS Beagle was surveying the port during the voyage of the Beagle. As a non-expert he tentatively identified the leg bones and fragments of spine he found as "some large animal, I fancy a Mastodon". In 1837, soon after the Beagle's return, the anatomist Richard Owen revealed that the bones including vertebrae from the back and neck were actually from a gigantic creature resembling a llama or camel, which Owen named Macrauchenia patachonica. In naming it, Owen noted the original Greek terms Μακρος (large or long), and αυχην (neck) as used by Illiger as the basis of Auchenia as a generic name for the llama, Vicugna and so on. The find was one of the discoveries leading to the inception of Darwin's theory. Since then, more Macrauchenia fossils have been found, mainly in Patagonia, but also in Bolivia, Chile and Venezuela.
Macrauchenia is featured in the episode "Saber-tooth" of the documentary Walking with Beasts, and individuals are featured in the 2002 Blue Sky film Ice Age and its sequels. It was included in the simulation game Zoo Tycoon: Complete Collection as part of the Dinosaur Digs Theme Pack and in Wildlife Park 2: Crazy Zoo as a cloneable beast. The related genus Cramauchenia was named by Florentino Ameghino as a deliberate anagram of Macrauchenia.
1.^ a b c "BBC - Science & Nature - Wildfacts - Macrauchenia". http://www.bbc.co.uk/nature/wildfacts/factfiles/455.shtml. Retrieved 2009-06-15.
2.^ Alberto L. Cione, Eduardo P. Tonni, Leopoldo Soibelzon: The Broken Zig-Zag: Late Cenozoic large mammal and tortoise extinction in South America. In: Revista del Museo Argentino de Ciencias Naturales. 5, 1, 2003, ISSN 1514-5158, S. 1–19, online (PDF; 243 KB)
3.^ a b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 248. ISBN 1-84028-152-9.
4.^ http://sedici.unlp.edu.ar/handle/10915/16838?show=full (in spanish)
5.^ MacFadden, B. J.; Shockey, B. J. (Winter, 1997). "Ancient feeding ecology and niche differentiation of Pleistocene mammalian herbivores from Tarija, Bolivia: morphological and isotopic evidence". Paleobiology (Paleontological Society) 23 (1): 77–100. JSTOR 2401158. http://www.jstor.org/stable/2401158. Retrieved 2011-05-27.
6.^ ed. Keynes, R. D. (2001). "Charles Darwin's Beagle Diary". Cambridge University Press. pp. 214. http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1925&pageseq=246. Retrieved 2008-12-19.
7.^ "Darwin Correspondence Project - Letter 238 — Darwin, C. R. to Henslow, J. S., Mar 1834". http://www.darwinproject.ac.uk/darwinletters/calendar/entry-238.html#mark-238.f3. Retrieved 2008-12-19.
8.^ Owen 1838, p. 35
• This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.
•Barry Cox, Colin Harrison, R.J.G. Savage, and Brian Gardiner. (1999): The Simon & Schuster Encyclopedia of Dinosaurs and Prehistoric Creatures: A Visual Who's Who of Prehistoric Life. Simon & Schuster.
•Jayne Parsons. (2001): Dinosaur Encyclopedia. DK.
•Haines, Tim & Chambers, Paul. (2006): The Complete Guide to Prehistoric Life. Canada: Firefly Books Ltd.
•Owen, Richard (1838). "Description of Parts of the Skeleton of Macrauchenia patachonica". In Darwin, C. R.. Fossil Mammalia Part 1 No. 1. The zoology of the voyage of H.M.S. Beagle. London: Smith Elder and Co. http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F8.1&pageseq=45