Macrauchenia

Taxobox
name = "Macrauchenia"
fossil_range = fossil range|7Late Miocene to Late Pleistocene
status = fossil

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image_width = 250px
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = †Litopterna
familia = †Macraucheniidae
genus = †"Macrauchenia"
subdivision_ranks = Species
subdivision = †"M. patagonica"
†"M. ullomensis"
†"M. boliviensis"
type_species = "Macrauchenia patagonica"
type_species_authority = Owen, 1838

"Macrauchenia" (literally "Big Neck") was a long-necked and long-limbed, three-toed South American ungulate mammal, typifying the order Litopterna. The oldest fossils date back to around seven million years ago, and "M. patagonica" disappears from the fossil record during the late Pleistocene, around 10 thousand years ago. "M. patagonica" was the best known member of the family Macraucheniidae, and is known only from fossil finds in South America, primarily from the Lujan Formation in Argentina. The original specimen was discovered by Charles Darwin during the voyage of the "Beagle". In life, "Macrauchenia" resembled a humpless camel with a short trunk, though it is not closely related to either camels or proboscideans.

History

"Macrauchenia" appeared in the fossil record some 7 million years ago in South America (in the Miocene epoch). It is likely that "Macrauchenia" arose from either "Theosodon" or "Promacrauchenia". Notoungulata and Litopterna were two ancient orders of ungulates which only occurred in South America. Many of these species became extinct through competition with invading North American ungulates during the Great American Interchange, after the establishment of the Central American land bridge. A few survivors of this invasion were the litopterns "Macrauchenia" and "Windhausenia" and the large notungulates "Toxodon" and "Mixotoxodon". These last original South American hoofed animals died out eventually at the end of the Pleistocene, along with numerous other large animals on the American continent (such as American elephants, horses, camels, saber-toothed cats and ground sloths). As this genus was the last of the litopterns, its extinction ended that line of mammals.

Anatomy

One striking characteristic of "Macrauchenia" is that, unlike most other mammals, the openings for nostrils on its skull were atop the head, leading some early scientists to believe that, much like a whale, it used these nostrils as a form of snorkel. Soon after some more recent findings, this theory was rejected. One insight into "Macrauchenia"'s physiology is that it apparently had unusually good mobility, being able to rapidly change direction when it ran. It is speculated that since "Macrauchenia" lived in an environment much like the savannas of modern-day Africa, it may have had a tawny coat to match the color of dried grass.

"Macrauchenia" is known, like its relative, "Theosodon", to have had a full set of 44 teeth.

Diet and behavior

"Macrauchenia" was an herbivore, likely living on leaves from trees or grasses. Scientists believe that, because of the forms of its teeth, it 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.

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 marsupials such as "Thylacosmilus" and "Borhyaena". 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 camelsFact|date=April 2008.

Fossil evidence

"Macrauchenia" was first discovered at the beginning of the nineteenth century in Patagonia (Argentina) by Charles Darwin, during his voyage aboard the HMS Beagle. He mistakenly identified it as a giant llama. Since then, more "Macrauchenia" fossils have been found, mainly in Patagonia, but also in Bolivia and Venezuela.

Cultural references

"Macrauchenia" is featured in the episode "Saber-tooth" of the show "Walking with Beasts", and indviduals are featured in the 2002 Blue Sky film Ice Age and its sequel, the 2006 film . It was included in the as part of the Dinosaur Digs Theme Pack and in as a cloneable beast.

References

*1911
*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.

External links

* [http://www.rau.edu.uy/uruguay/iconos/macrauke-.gifAn artist's rendition] of a Macrauchenia. Retrieved from the Red Académica Uruguaya [http://www.rau.edu.uy/uruguay/historia/megafauna.htm megafauna page] .