著者

新村 龍也 沢田 健

出版者

日本地球化学会

雑誌

地球化学 (ISSN:03864073)

巻号頁・発行日

vol.44, no.1, pp.17-29, 2010

被引用文献数

2

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Dietary preferences of archaeological and paleontological animals have been investigated based on stable carbon isotope ratios (δ¹³C) of collagen and non-collagenous proteins in fossil bones. The δ¹³C of individual compound in lipids from fossil bones were recently applied to the reconstruction of palaeodietary of animals. In the present study, we analyze the concentrations, class distributions, and δ¹³C values of fatty acids and steroids in the Pleistocene to Pliocene fossil whale and the Miocene fossil sea cow (<i>Dusisiren</i> sp.) bones, and evaluate their applicability as indicators of palaeodietary and fossil diagenesis. Biosynthetic steroids as cholesterol are detected in the Pleistocene whale bones, while the sterols are very poor in the older Pliocene whale samples, of which major steroids are their diagenetic compounds such as cholestanes and cholestenes. However, a large amount of cholesterol characterizes the Miocene fossil sea cow bone. We also can identify labile unsaturated fatty acids from all fossil whale and sea cow bones. It is suggested that the relative abundances of unsaturated to saturated fatty acids can be useful indicator for estimating diagenetic stage of fossil bones and checking contamination. The δ¹³C values of fatty acids in the fossil whale and sea cow bones range widely from -25.7 to -16‰, and there are differences of 1 to 4‰ between several fatty acid homologues within the same sample. Thus, the δ¹³C analyses of fatty acids in fossil bones may be less applicable for reconstructing palaeodietary. On the other hand, the δ¹³C values of steroidal compounds within the same sample are almost similar, although these values vary ranging between -29.6‰ and -24.4‰ among the different whale samples. Furthermore, the steroidal δ¹³C value in the sea cow sample is -20.5‰, which is concordant with that of food in sea cow. From these results, the δ¹³C value of steroid in fossil bone can be strongly useful tool for reconstructing palaeodietary of paleontological animal.