Dissertation Research: Paleovegetational Response to Volcanism: Eocene/Oligocene Lower Cedarville Flora, California

9520826 Fisher在加利福尼亚州北部、俄勒冈州和华盛顿州的许多地点，火山沉积保存了古老的植被类型，并使随着时间的推移对植物物种更替和栖息地变化趋势的关键分析成为可能。在加州大学圣巴巴拉分校理查德·费舍尔教授的指导下，研究生杰弗里·迈尔斯正在研究西方始新世和渐新世的沉积，大约有3000万年的历史，以评估在相对较短的地质时间跨度内大片地区的植被变化。其目标是区分植被的单一、主要的长期转变(潮湿的热带森林到季节性的温带森林)或当地栖息地类型的更复杂的马赛克模式。将访问和采样许多相同年代的沉积物，并确定它们的主要植物成分；这项研究的一个关键方面是纳入对沉积后过程(所谓的挖掘过程，如腐烂和当地的水运或动物运输)的现代分析，以确保化石沉积物准确地反映当地的植被。对全球气候变化及其环境影响的兴趣加强了对化石记录进行精细分析的必要性。这项拟议研究的重点是始新世-渐新世，强调全球变冷的时间，由此导致温带植被的转移。植被物种组成变化的时间尺度是什么以及如何变化，是古生物学中尚未解决的主要问题，本研究对此采取了严格的挖掘方法。

9520826 Fisher At numerous sites in northern California, Oregon, and Washington, volcanic deposits preserve ancient vegetational types and make possible the critical analysis of trends in plant species replacement and habitat change through time. Graduate student Jeffrey Myers under the guidance of Professor Richard Fisher at the University of California-Santa Barbara is studying deposits of Eocene and Oligocene age, ca. 30 million years old, in the West, to assess vegetational changes across a broad region of the landscape over a relatively short span of geological time. The goal is to distinguish between a single, major secular shift in vegetation (moist humid tropical to seasonal temperate forest) or a more complex mosaic pattern of local habitat types. Numerous deposits of the same age will be visited and sampled, and their major plant components identified; a critical aspect of the research is to incorporate modern analyses on post-depositional processes (so-called taphonomic processes like decay and local transport by water or by animals) so ensure that fossil deposits accurately reflect local vegetation. Interest in global climate change and its environmental effects reinforces the need for fine-scale analysis of the fossil record. The Eocene-Oligocene focus of the proposed research emphasizes a time of global cooling, with resulting shifts in temperate-zone vegetation. How and over what timescales the vegetation changes in species composition are major unresolved questions in paleontology, to which this research brings a rigorous taphonomic approach.