澄江生物群背景层泥岩中软躯体化石的形态解剖学及保存机制

Specimens from the background mudstone of the Chengjiang biota have been ignored for long time, primarily due to the rarity and poor quality of the soft-bodied fossils within this algae-rich and slowly deposited sediment. However, recent discoveries reveal that morphological and anatomical features can also been preserved in the background mudstone as excellently as, if not better than the fossils from the event mudstone of Yu’anshan Member, such as the circular system of Fuxianhuia, brains of Lyrarapax unquispinus, a newly recorded anomalocaridids from the Chenjiang biota. By investigating the specimens deposited in Yunnan Key Laboratory for Palaeobiology and that will be collected by this project, this work aims to conduct a comparative study on the soft-bodied fossils from the background mudstone of Chengjiang biota, including their potential of preservation and the morpho - anatomical features. By employing new techniques, such as the SEM-EDX and Micro-CT analyses, this work will also focus on the mechanisms that underlying the preservation of soft-bodied fossils from the background mudstone, trying to explain why fossils preserved within background and event mudstones are different. ..The Chengjiang biota is among the most important fossil Lagerstätte of Cambrian in understanding the early radiation of eumetazoans. Additional data from the background mudstone of the Chengjiang biota, which has been ignored for long time, will help us to understand the evolutionary pattern of some characters. The conditions that underlying the preservation of soft-body fossils within slowly deposited background mudstone will shed light on the taphonomy of the BST fossils worldwide.

云南东部寒武系筇竹寺组玉案山段的背景层泥岩是澄江生物群重要的化石赋存层位，但其中的化石（包括软躯体化石）一直缺少详细的形态解剖研究。扫描电子显微镜-能谱分析的最新研究结果表明，背景层泥岩中的化石可以保存非常精美的软躯体形态解剖特征，但其保存形式是碳质薄膜，不同于事件层泥岩中软躯体化石的黄铁矿化保存。本项目拟通过系统的野外调查工作，运用扫面电子显微镜—能谱分析、计算机断层扫面成像等技术方法，对澄江生物群背景层泥岩中的软躯体化石进行形态学、解剖学及其保存机制的研究工作。本项目有望为寒武纪生命大爆发时期后生动物形态解剖特征的演化模式提供更多的证据，为研究寒武纪布尔吉斯页岩型化石的埋藏机制提供新的线索。

云南东部寒武系筇竹寺组玉案山段的背景层泥岩是澄江生物群重要的化石赋存层位，但其中的化石一直缺少详细的形态解剖研究。本项目执行期间，对多个剖面背景层泥岩中的软躯体化石进行了系统采集，重点对射齿动物、开腔骨类、足杯虫类和古虫动物的形态解剖特征开展了研究工作；项目还通过沉积学分析和地球化学的手段（C-S-Fe同位素），对背景层和事件层化石保存的环境条件进行了研究，均取得了重要进展。项目组成员以第一作者/通讯作者在Nature Ecology & Evolution，Current Biology, Proceedings of the Royal Society B: Biological Science等学术杂志上发表SCI论文10篇，合著英文专著1部；项目组成员共参加国际会议21人次，发表会议论文摘要25篇；参加国内会议7人次，发表会议论文摘要3篇；项目主持人获得云南省自然科学一等奖1项（排名第三），并入选“百千万人才工程”国家级人选，获“有突出贡献中青年专家”称号。.项目重点依托背景层泥岩化石的新发现，主要在以下四个方面取得了突破：1）对射齿动物、足杯虫类和古虫动物的系统分类学进行了梳理，报道新的疑难化石4属7种。2）利用疑难化石的发现，在部分动物门类早期演化方面取得新的认识；例如从个体发育学的角度证实了开腔骨类和海绵动物的亲缘关系更接近；证实了足杯虫和先光海葵是栉水母动物的干群，提出栉水母动物起源的新假说。3）在部分疑难化石的个体生态学方面取得了开创性工作，提出了射齿动物“功能性头部”的概念，从功能形态学的角度证实了部分射齿动物确实是寒武纪海洋里的顶级捕食者；发现了世界上已知最早的共生蠕形动物，并确认了该共生蠕虫具有宿主特异性和宿主迁移的生态学特性。4）项目组核心成员祁昌实博士通过地球化学的手段揭示了背景层泥岩沉积时为贫氧环境，而事件层则代表着富氧环境，这种氧含量在海水中的变化可能是澄江化石以特异形式保存的最主要原因之一。（字数：732）