Megafossil Evidence for Ordovician/Silurian Terestrial Biotas

奥陶纪-志留纪陆生生物的巨化石证据俄亥俄州大学Rothwell（CN-0308931）摘要这项研究探索了复杂陆地生命的起源，重点是建立第一个陆地生态系统。这项工作的重点是至少4.4亿年前居住在陆地表面的生物群落，这为土地的殖民提供了第一个直接证据。这些社区的代表丰富的碳质中型和巨型化石的叶状生物和/或共生协会，保存在上奥陶世和下志留世河流和三角洲沉积的阿巴拉契亚盆地。这些标本是迄今为止发现的最古老的宏观陆地化石，表明最早的复杂陆地生物具有比目前认识到的更大的化石化潜力。他们还记录了大量的叶状体形式的地面覆盖物在陆地上建立的时间远远早于目前所知的时间。拟议研究的目标是在复杂生物体最初在陆地上定居和维管植物出现之间的关键但鲜为人知的时间间隔内发展有关陆地生命的基本知识。对这些奥陶纪-志留纪陆生生物化石的研究主要集中在1）记录第一个陆地群落，2）确定单个化石的形态、解剖和超微结构特征，3）开始了解生物多样性、系统亲缘关系和生物相互作用。这些目标将通过实验室准备和已经收集的化石的特征确定来实现。这项工作由PI以及俄亥俄州大学的研究生和本科生研究人员进行。通过与同事合作进行系统的调查，这些同事要么是化石最有可能相关的活生物体的专家，要么是来自同期地层的化石palynomorphs。研究结果将通过出版物和在国家和国际会议上的介绍加以传播，并通过本科生实验室练习和在互联网数据库上公布新的研究结果来实现更多的教育推广。

EAR-0308931MEGAFOSSIL EVIDENCE FOR ORDOVICIAN-SILURIAN TERRESTRIAL BIOTASGar W. Rothwell (EAR-0308931) Ohio UniversityABSTRACTThis research explores the origins of complex life on land, with an emphasis on establishment of the first terrestrial ecosystems. The work focuses on fossilized communities of organisms that inhabited the land surface at least 440 million years ago, and that provide the first direct evidence for colonization of the land. These communities are represented by abundant carbonaceous meso- and megafossils of thalloid organisms and/or symbiotic associations that are preserved in Upper Ordovician and Lower Silurian fluvial and deltaic deposits of the Appalachian Basin. Specimens are the oldest macroscopic terrestrial fossils ever discovered, demonstrating that the earliest complex land organisms had much greater fossilization potential than is currently recognized. They also document that a substantial ground cover of thalloid forms was established on the land far earlier than presently known. Goals of the proposed research are to develop fundamental knowledge about terrestrial life during the crucial but poorly known time interval between initial colonization of land by complex organisms and the emergence of vascular plants. Investigations of these Ordovician-Silurian terrestrial fossils focus on 1) documenting the first land communities, 2) determining the morphological, anatomical and ultrastructural characters of individual fossils, and 3) beginning to develop an understanding of the diversity, systematic affinities, and biological interactions of the fossilized organisms. These goals will be achieved through laboratory preparations and character determinations for fossils that already have been collected. The work is being conducted by the PI, and by graduate and undergraduate student researchers at Ohio University. Systematic investigations are being pursued through collaborations with colleagues who are experts on either the living organisms to which the fossils are most likely related, or on fossil palynomorphs from contemporaneous strata. Results will be disseminated by publications and presentations at national and international meetings, with additional educational outreach being achieved through undergraduate student laboratory exercises, and by posting of the new findings on internet data bases.