2009年第47卷 第4期: 282-298
Late Cenozoic environmental changes in the
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.