ABSTRACT

South America is well known for its abundance of Quaternary fossiliferous deposits, but well-preserved fossil remains from well-dated sites are scarce in the Atacama Desert and adjacent arid Andes. Here we report on a partially complete skeleton (46%) of a single young (ca. 3–4 years old) extinct horse discovered in the Salar de Surire, a salt flat located on the Andean altiplano of northern Chile (4,250 m asl). Comparative and osteometric morphological analyses identify the specimen as a South American endemic horse Hippidion saldiasi Roth, 1899. A direct AMS radiocarbon date on bone collagen yielded a calibrated age of 13,170 cal yr BP (2σ range: 13,300–13,060 cal yr BP) indicating that it lived near the end of the last glaciation. The body mass of the individual was calculated at approximately 326.4 kg, close to the upper limit of the larger sizes reported for the genus. Stable isotope evidence shows that the Salar de Surire horse relied on an almost 100% C3 diet that is mostly consistent with Hippidion specimens from other environments that also consumed either mixed C3/C4 or fully C3 diets. This finding is now the southernmost high-elevation record for this species and provides further evidence for the broad geographic and ecological distribution of this genus throughout southern South America.

摘要

南美以其第四纪化石沉积物丰富而著称，但在阿塔卡马沙漠和邻近的干旱安第斯山脉中，保存完好的来自化石遗址的化石遗骸稀少。在这里，我们报告了在Salar de Surire（位于智利北部安第斯高原）（4,250 m asl）上的一个盐滩发现的一匹年轻（约3–4岁）灭绝的马的部分完整的骨骼（46％）。 。比较和骨形态学分析鉴定该标本为南美地方性马Hippidion saldiasi罗斯，1899年。直接AMS放射性碳测得的骨胶原的校正年龄为BP 13,170 cal yr（2σ范围：13,300-13,060 cal yr BP），表明它的生存期在最后一次冰期即将结束时。计算得出该人的体重约为326.4 kg，接近该属报道的较大体型的上限。稳定的同位素证据表明，Salar de Surire马依赖于几乎100％的C3饮食，这与来自其他环境的嬉皮动物标本相一致，而后者也消耗了C3 / C4或完全C3饮食。该发现现已成为该物种最南端的高海拔记录，并为整个南美南部该属的广泛地理和生态分布提供了进一步的证据。