黄河流域出土龙山时期扬子鳄骨板的多种同位素分析

Multi-isotope analysis on the Yangtze Alligator osteoderm unearthed from Yellow River Valley during the Longshan Period

扬子鳄现今生活在长江下游地区,但是在龙山时代(5000~4000 BP cal.)黄河流域多处遗址中发现了扬子鳄骨板。为判断龙山时代华北地区的扬子鳄是本地生长还是来自与长江流域的贸易交换,本研究对芮城清凉寺、邹平丁公、泗水尹家城3处遗址出土的7例鳄鱼骨板进行了Sr、C和O同位素分析。3处遗址鳄鱼骨板的87Sr/86Sr值均落入当地Sr同位素背景范围内,且山东样本的δ18O比值高于山西样本,符合δ18O值由内陆向沿海升高的趋势,证明这些扬子鳄个体属于本地物种的可能性很大。扬子鳄骨板的δ13C值都明显高于世界其他内陆地区淡水系统的鳄鱼,显示出复杂的饮食特征。上述结果有助于深入了解不同时期扬子鳄的地理分布变迁,对重建距今四千多年前华北地区的古环境具有重要意义,同时也对龙山先民与扬子鳄的关系提出了新的疑问。

Chinese alligators(Alligator sinensis)nowadays inhabit the downstream Yangtze River,but the alligator remains were found at several archaeological sites in Yellow river region during the Longshan period(5000~4000 BP cal).To determine whether these Yangtze alligators were indigenous or were part of long-distance trading from Yellow river region,we conducted Sr,C and O isotopic analysis of seven alligator osteoderms samples from Qingliangsi,Dinggong and Yinjiacheng sites dating from the Late Longshan Period.The 87Sr/86Sr ratios of these alligator osteoderms in three sites fall into the local bioavailable 87Sr/86Sr ranges,and theδ18O ratio of Shandong samples was higher than Shanxi samples,which was consistent with the trend ofδ18O increasing from the inland to coastal,indicating that these remains are mainly indigenous.Theδ13C of Chinese alligator osteoderm were significantly higher than the rest of the world’s inland freshwater systems crocodile,showing complex diet characteristics.The result of isotopes that is better to understand the geographical distribution change of Yangtze alligators in different periods,which is of great significance for reconstructing the paleo-environment of North China more than 4000 years ago.It also raised new questions about the relationship between the ancestors of Longshan and the Chinese alligator.