The extinct, giant giraffid Sivatherium giganteum: skeletal reconstruction and body mass estimation

Sivatherium giganteum is an extinct giraffid from the Plio–Pleistocene boundary of the Himalayan foothills. To date, there has been no rigorous skeletal reconstruction of this unusual mammal. Historical and contemporary accounts anecdotally state that Sivatherium rivalled the African elephant in terms of its body mass, but this statement has never been tested. Here, we present a three-dimensional composite skeletal reconstruction and calculate a representative body mass estimate for this species using a volumetric method. We find that the estimated adult body mass of 1246 kg (857—1812 kg range) does not approach that of an African elephant, but confirms that Sivatherium was certainly a large giraffid, and may have been the largest ruminant mammal that has ever existed. We contrast this volumetric estimate with a bivariate scaling estimate derived from Sivatherium's humeral circumference and find that there is a discrepancy between the two. The difference implies that the humeral circumf...

西瓦兽（Sivatherium giganteum）是一种产自喜马拉雅山麓上新世-更新世交界地层的已灭绝长颈鹿科（Giraffidae）动物。截至目前，学界尚未针对这一特殊哺乳动物开展过严谨的骨骼重建研究。历史记载与当代研究均轶事性地指出，西瓦兽的体质量可与非洲象比肩，但这一说法从未得到实证检验。本研究完成了该物种的三维复合骨骼重建，并采用体积法计算了其代表性体质量估算值。研究结果显示，西瓦兽成年个体的体质量估算值为1246 kg（区间范围857—1812 kg），并未达到非洲象的体质量水平，但确证其为体型庞大的长颈鹿科动物，且可能是地球历史上体型最大的反刍类哺乳动物。本研究将该体积法估算结果与基于西瓦兽肱骨周长推导的双变量缩放估算结果进行对比，发现二者之间存在显著差异。这一差异表明……