Eocene Floras of the Northern Hemisphere: Paleoclimate and Implications for Large Scale Floristic Interchange

北方半球始新世植物群：通过与德国和中国的同事合作，将对中纬度北美、欧洲和亚洲的始新世早期和中期植物群进行详细的第一手比较，作为评估气候比今天温暖的时期植物地理格局的一种手段，大陆间的高纬度植物区系交流也有潜力。 PI将比较北美（美国西部的西分支溪和绿色河植物群）、西欧（德国的梅塞尔和埃克费尔德）和东亚（中国抚顺和桦甸）始新世早期和中期湖泊沉积物中保存的巨型化石植物群。 每个这些组合的年龄是通过相关的哺乳动物群和/或放射性测年火山灰的相关性建立的。 每个地点的古气候将根据叶相分析进行比较，以给出年平均温度和降水量的近似值。 将进行大陆内和洲际植物区系比较，以确定始新世早期和中期每对大陆之间共享与特有分类群的相对比例。 由此产生的意见将：1）提供这些广泛分离的湖盆的年平均温度和降水量的近似值，2）表明在早始新世和中始新世不同路线的洲际传播的相对重要性，和3）便于比较在第三纪早期在哺乳动物中观察到的植物的传播模式。

Eocene floras of the Northern Hemisphere: paleoclimate and implications for large scale floristic interchangeStephen ManchesterEAR-0087780AbstractDetailed first-hand comparisons will be made between selected early and middle Eocene floras of mid-latitude North America, Europe and Asia through collaboration with colleagues in Germany and China as a means of assessing phytogeographic patterns during a time when the climate was warmer than today, and there was potential for high-latitude floristic exchange between continents. PI will compare megafossil floras preserved in the sediments of early and middle Eocene lakes from North America (West Branch Creek and Green River floras, western US), western Europe (Messel and Eckfeld, Germany), and Eastern Asia (Fushun and Huadian, China). The ages of each these assemblages are established through correlations of associated mammal faunas and/or radiometrically dated volcanic ashes. Paleoclimate of each of the sites will be compared based on foliar physiognomic analyses to give approximations of mean annual temperature and precipitation. Intra- and intercontinental floristic comparisons will be made to determine the relative proportion of shared vs. endemic taxa between each pair of continents in the early and middle Eocene. The resulting observations will: 1) provide approximations of the mean annual temperature and precipitation of these widely separated lake basins, 2) indicate the relative importance of different routes of intercontinental dispersal in the early and middle Eocene, and 3) facilitate comparison of dispersal patterns in plants with those observed in mammals during the early Tertiary.