like that of the saiga antelope, perhaps to keep dust out of the nostrils. However, a 2018 study comparing the skulls of tapirs and various other herbivorous extant and extinct mammal species instead saw similarities with the skulls of moose, suggesting that Macrauchenia and other macraucheniids, such as Huayqueriana did not possess trunks. However, pictographs depicting various extinct megafauna dated to around 12,600 to 11,800 years ago from the Serranía de La Lindosa rock formation of Guaviare, Colombia showed what appears to be a possible trunked macraucheniid, presumably Xenorhinotherium. The snout of Macrauchenia is completely enclosed by bone, and the animal has an elongated neck that allowed it to reach upward; no living mammal with a proboscis has these features. An alternative hypothesis is that these litopterns were high browsers on tough and thorny vegetation, and retracted nostrils allowed them to reach leaves without being impaled in the nose. Sauropod dinosaurs (reconstructed as high browsers on conifer needles and cycads) have similar snouts, and living giraffes and gerenuks, high browsers on thorny vegetation, have more retracted nostrils than related taxa with other feeding habits. One insight into Macrauchenia'''s habits is that its ankle joints and shin bones may indicate that it was adapted to have unusually 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. Paleobiology Macrauchenia was a 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. A dental microwear, occusal enamel, and carbon isotope analysis of Macrauchenia and Xenorhinotherium found that both were grazers on C3 grasses. The genus was widespread, found in environments that ranged from dry to humid, from southern Chile to northeastern Brazil and the coast of Venezuela. Fossils of M. ullomensis have been found in Bolivia at altitudes up to 4000 meters. Habits and diet may have varied depending on the environment, but in plant feeders an elongated neck is usually an adaptation to allow high browsing on trees and shrubs. As the genus was not confined to forest, it was probably able to exploit more marginal