Abstract

To assess the trophic position of the exceptionally large-sized brown bears from the Pleistocene of Yakutia, we used stable nitrogen and carbon isotope analyses of the collagen contained in fossil bones and teeth. Modern brown bears of Yakutia were compared to the large Pleistocene predators. As a result of the measurements taken for the Pleistocene bears, we obtained δ¹³С values typical of terrestrial ecosystems and relatively high δ¹⁵N values typical of such Pleistocene predators as the cave lion. We explain the high δ¹⁵N values of the bone collagen of the study fossil bears, as well as other Pleistocene brown bears of Yakutia and Chukotka, by (1) the absence of large competitors such as Arctodus simus, which allowed the bears to use large amounts of animal food; (2) the physiological effect of hibernation, expressed in an increased content of ¹⁵N in the bone collagen; and (3) an increased content of ¹⁵N in vegetation due to more severe climatic conditions, which affects the isotopic composition of the entire mammoth fauna of western Beringia. The δ¹³C and δ¹⁵N values of modern brown bears in Yakutia indicate a plant diet, suggesting that the modern brown bears (compared to fossils) occupy a fundamentally different trophic niche adapted to the modern low-productivity ecosystems of Yakutia.

中文翻译：

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基于稳定同位素分析的雅库特更新世和现代棕熊（Ursus arctos）的营养位置。

摘要

为了评估雅库特更新世的特大型棕熊的营养位置，我们对化石骨骼和牙齿中所含的胶原进行了稳定的氮和碳同位素分析。将雅库特（Yakutia）的现代棕熊与大型更新世捕食者进行了比较。作为为更新世熊测量的结果，我们得到的δ ¹³ С值典型的陆地生态系统和相对高的δ ^15个N个值典型的这种更新世食肉动物作为洞穴狮子的。我们解释高δ ^15个研究化石熊，骨胶原的N个值以及雅库特和楚科奇的其他更新世棕熊，通过（1）不存在的大竞争对手如Arctodus simus，允许熊使用大量动物性食物；（2）冬眠的生理作用，以骨胶原中¹⁵ N的含量增加表示；（3）由于更恶劣的气候条件，植被中¹⁵ N的含量增加，这影响了Beringia西部整个猛mm动物的同位素组成。的δ ¹³ C和δ ^15个雅库特现代棕熊的N个值指示植物饮食，表明现代棕熊（相比于化石）占据一种根本不同的营养生态位适于雅库特现代低生产率的生态系统。