Ediacara Fossils Preserved in Ediacaran Bituminous Limestone

埃迪卡拉化石保存在埃迪卡拉纪沥青石灰岩中肖树海，弗吉尼亚理工学院和州立大学，北京-0545135摘要埃迪卡拉化石代表了埃迪卡拉纪晚期（大约5.8 - 5.4亿年前）一些最早的、复杂的大型生物。它们于1872年在纽芬兰首次被发现，后来在纳米比亚，澳大利亚，俄罗斯，西伯利亚，英格兰，北美和中国南方被发现。尽管它们在理解宏观生命的早期进化、它们广泛的地理分布以及它们作为科学调查目标的悠久历史方面具有重要意义，但埃迪卡拉化石的形态学、古生态学和系统发育解释尚未完全解决。埃迪卡拉化石的保存方式是一个关键的挑战：几乎所有的埃迪卡拉化石都是以铸模和模子的形式保存在砂岩或粉砂岩中，因此很难重建其形态。本项目旨在研究中国南方长江三峡地区灯影组（5.51 - 5.42亿年前）沥青灰岩中保存异常的埃迪卡拉组合。初步调查发现了至少五种新的埃迪卡拉类型。这些化石似乎是在三维空间和原地保存的。它们中的一些显示仍然是降解的有机壁，和形态重建表明，他们生活procumbently或附近的水-沉积物界面。本课题的近期目标是对长江三峡地区灯影组进行系统的野外调查和采集，并利用连续薄片、光学显微镜、扫描电镜和电子探针等技术对灯影组Ediacara化石进行细致的研究。本研究的长期目标是解决灯影埃迪卡拉组合的生物多样性、体型、埋藏学和古生态学相关问题。因此，这项研究的科学意义是推进我们对最早的复杂大型生物-埃迪卡拉生物群进化的认识。

Ediacara Fossils Preserved in Ediacaran Bituminous LimestoneShuhai Xiao, Virginia Polytechnic Institute and State UniversityEAR-0545135AbstractEdiacara fossils represent some of the earliest, complex macroorganisms in the late Ediacaran Period (approximately 580-540 million years ago). They were first discovered in Newfoundland in 1872, and have later been found in Namibia, Australia, Russia, Siberia, England, North America, and South China. Despite their importance in understanding the early evolution of macroscopic life, their wide geographic distribution, and their long history of being targeted for scientific investigation, the morphological, paleoecological, and phylogenetic interpretation of Ediacara fossils has not been completely resolved. A key challenge has to do with the way most Ediacara fossils are preserved: almost all Ediacara fossils are preserved as casts and molds in sandstone or siltstone, making it difficult to reconstruct the morphologies.This project is designed to study an unusually preserved Ediacara assemblage from bituminous limestone of the Dengying Formation (551-542 million years ago) in the Yangtze Gorges area of South China. Preliminary investigation has recovered at least five new Ediacara forms. The fossils appear to have been preserved in three dimensions and in situ. Some of them show remains of degraded organic walls, and morphological reconstruction indicates that they lived procumbently at or near the water-sediment interface. The immediate objective of this project is to carry out systematic field investigation and collection of the Dengying Formation in the Yangtze Gorges area, and to carefully study the Dengying Ediacara fossils using serial thin section, light microscopy, SEM, and electron microprobe techniques. The long-term goal of this research is to address questions related to the biodiversity, bodyplan, taphonomy, and paleoecology of the Dengying Ediacara assemblage. Thus, the scientific significance of this research is to advance our knowledge about the evolution of the earliest complex macroorganisms - the Ediacaran biota.