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MacraucheniaMacrauchenia 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 on 9 February 1834 at Port St Julian, Patagonia, during the voyage of the Beagle . Darwin tentatively identified the leg bones and fragments of backbone as "some large animal, I fancy a Mastodon". In 1837, Richard Owen aid the bones were from a gigantic creature resembling a llama or camel [7,8].
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 had a full set of 44 teeth.
Macrauchenia was a herbivore and was probably a mixed feeder, eating leaves from trees or grasses . Scientists think that the teeth indicate that Macrauchenia used its trunk to grasp leaves and other food. It is also believed that it lived in herds to escape predators.
When Macrauchenia first arose, its predators incldued terror birds such as Andalgalornis and carnivorous sparassodontids such as Thylacosmilus. When the Panama Isthmus formed during the late Pliocene/Early Pleistocene, large cats reached South America from North America. Macrauchenia probably tried to outrun its predators by twisting and turning at high speed, but it may have kicked them with its long, powerful legs.