2009年第47卷 第4期: 282-298
作者：邓 涛
摘要：哺乳动物群的演替过程在重建古环境和古气候中具有重要的作用。群落线(cenogram)是将陆生哺乳动物群中非肉食性种类按体重分布顺序排列的一种曲线，并可在图中将肉食性种类单独排序，以便显示动物群的整体组成。通过与现生哺乳动物群的比较，化石动物群的群落线已经被用来推断古环境及其在地质历史时期的变化。基于甘肃临夏盆地晚新生代哺乳动物群的群落线进行古环境重建，时代从晚渐新世直到早更新世。大多数化石种类的体重通过下第一臼齿面积与体重的回归公式来估计，少数种类用其他牙齿或肢骨来估计。大多数体重估计的测量数据来自临夏盆地的化石，少数取自文献。对7个化石动物群分别计算群落线的统计结果，在此基础上进行古环境解释。这些分析揭示了临夏盆地在晚中新世、早上新世和早更新世具有开阔的环境，晚渐新世是半开阔的林地，而中中新世为比较紧密的森林；在晚渐新世和晚中新世早期气候干燥，晚中新世的其他时段以及早上新世和早更新世为半干旱环境，而中中新世时期相当湿润。
关键词：临夏盆地，晚新生代，哺乳动物，古环境，群落线
卷期：47卷 04期
Late Cenozoic environmental changes in the
DENG Tao
Abstract The evolutionary history of mammalian communities is significant for reconstructing past environments and climate. A cenogram is a rank-ordered body mass distribution of non-predatory terrestrial mammal species within a fauna. Based on comparisons with modern faunas, cenograms of fossil faunas have been used for inferring environments and their changes through geological time. In this paper, an environmental reconstruction based on the Late Cenozoic mammalian faunas of the Linxia Basin (Gansu, China), ranging in age from the Late Oligocene to the Early Pleistocene, is presented using the cenogram method. Body sizes for fossil taxa were estimated using regressions of body weight based on the area of the first lower molar for most species and on other teeth or limb bones for a few species. Most measurements for the body estimations are from the Linxia fossils, while a few are from the literature. Cenogram statistics are calculated for seven fossil faunas, allowing paleoenvironmental interpretations to be made. These analyses reveal open conditions during the Late Miocene, Early Pliocene and Early Pleistocene; less open conditions during the Late Oligocene but a closed environment during the Middle Miocene; arid conditions during the Late Oligocene and earliest Late Miocene; less arid during the Late Miocene, Early Pliocene, and Early Pleistocene but humid during the Middle Miocene.
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