Biodiversity at an epoch boundary: Paleocene-Eocene mammals and continental paleoclimates

海洋沉积物表明古新世-始新世 过渡涉及全球变暖， 温度梯度、海洋主导的向极热输送、 大气环流弱。 大陆性气候应该是 温暖，但在这种条件下，季节性很强，但始新世 大陆植物区系通常被解释为非落叶的， 非季节性 气候和季节性的独立证据是 从哺乳动物化石中寻找。 25个大型动物样本 可从一个地层剖面中的连续层段获得 在怀俄明州西北部，密集的收集将使 至少有15个以上的样本。 这40个动物群样本跨越了 时间间隔从约58至56 Ma--时间间隔包括 古新世-始新世界线与始新世最早期变暖 活动 样本的时间间隔与ODP中的时间间隔相当 丹 物种丰富度、物种多样性、k秩分析 每个家族物种的丰度，最大哺乳动物的体型， 和等级-体型动物群结构应该提供一个记录， 大陆古温度、湿度和森林变化 200万美元的开放性研究间隔。 牙本质间距 人们正在研究冠齿象象牙中的纹层， 关于季节性的新信息。

Oceanic sediments indicate that the Paleocene-Eocene transition involved global warming, with a reduced latitudinal temperature gradient, ocean-dominated poleward heat transport, and weak atmospheric circulation. Continental climates should be warm but highly seasonal under these conditions, but Eocene continental floras are usually interpreted as non-deciduous and non-seasonal. Independent evidence of climate and seasonality is sought from fossil mammals. Twenty-five large faunal samples are available from successive intervals in one stratigrpahic section in northwestern Wyoming, and intensive collecting will make at least 15 more samples large. These 40 faunal samples span the interval from ca.58 to 56 Ma-- the interval including the Paleocene-Eocene epoch boundary and earliest Eocene warming event. Temporal spacing of samples is comparable to that in ODP cores. Analysis of species richness, species diversity,k rank abundance of species-per-family, body size of the largest mammal, and rank-body-size faunal structure should provide a record of change in continental paleotemperature, moisture and forest openness for the 2 m.y. study interval. Spacing of dentinal laminae in tusks of Coryphodon is being investigated as a source of new information on seasonality.