Taphonomy and Paleoecology of Ediacaran Assemblages (Flinders Ranges, South Australia): Do we Have a Census?

末元古代埃迪卡拉动物群仍然是现代古生物学中最大的争议之一。它的时间位置在所谓的寒武纪大爆发之前，这表明它应该为动物的早期进化提供关键信息。对埃迪卡拉纪生物群的研究传统上集中在对单个分类群的描述和解释上，最近则集中在地层分布和古地理上。埃迪卡拉动物群研究的一个主要缺陷是缺乏对群落结构和其他协同学方面的研究。没有先验的理由说明为什么晚元古代的组合不应该用与显生宙群落相同的方法来研究。特别是埃迪卡拉纪化石的保存模型（Gehling 1999）预测，它们可能会产生人口普查社区。拟议的研究项目将是第一个详细系统的实地分析一个高多样性的埃迪卡拉组合（包括所有的身体和痕迹化石，问题结构和无机表面），通过研究在南澳大利亚选定的地方，在那里可以挖掘出大型顺序层理平面（超过数百平方米）。野外工作规程包括挖掘和重新组合已仔细记录地层演替的地层。将对这些层理面进行详细检查，并根据保存的性质和性质记录和分类所有的体和痕迹化石和沉积结构。然后用标准的统计方法分析化石的分布。初步研究表明，在直接层序中，各层间的化石和层理面性质存在着意想不到的巨大差异。该项目的一个重要目的是解释这些观察结果；这些差异在多大程度上代表了保存性偏见或复杂的群体？该项目的一个重要部分是详细记录痕迹化石以及众多无机和有机起源的问题结构。在此之前，人们还没有详细地研究过晚元古代痕迹化石的分布情况，以及这些痕迹所处的地层的性质。由于对晚元古代痕迹化石的大量错误鉴定和结构问题，其记录是有问题的。这些有问题的结构在很大程度上被忽视了，这些研究集中在离散的身体化石上，但它们提供了这些群落性质的重要信息。只有通过检查大的层理平面表面，我们才能了解这些物体的性质，我们才能最终了解埃迪卡拉纪组合上的地层学叠印，从而揭开埃迪卡拉纪的生态学。更大范围的撞击：diacaran组合是地球上最古老的、多样化的宏观化石组合。因此，许多地质学家和生物学家对它们非常感兴趣。为这项研究挖掘的床架将以一种允许学生和其他感兴趣的团体参观的开发场地的方式重新组装（如先前与土地所有者安排的那样）。该项目非常适合本科生参与，并为2名本科生前往澳大利亚并在实地工作编列了预算。当地澳大利亚人也将参与挖掘和相关活动。通过这种方式，可以传达该矿床和其他类似矿床的意义。该项目将开发和保护一个世界级的化石产地，其全部潜力尚未开发。

The terminal Proterozoic Ediacaran biota remains one of the great controversies inmodern paleontology. Its temporal position, preceding the so-called Cambrian explosion,suggests that it should provide key information on the early evolution of animals. Studies of theEdiacaran biota have traditionally focussed on the description and interpretation of individualtaxa and more recently on the stratigraphic distribution and paleogeography. A majorshortcoming in the study of the Ediacaran biota is the paucity of studies of the communitystructure and other aspects of synecology. There is no a priori reason why late Proterozoicassemblages should not be examined by the same means as Phanerozoic communities.Particularly as models for the preservation of Ediacaran fossils (Gehling 1999) predict that theypotentially should yield census communities. The proposed research project will be the firstdetailed systematic field analysis of a high-diversity Ediacaran assemblage (including all bodyand trace fossils, problematic structures and inorganic surfacesls) by the study of selectedlocalities in South Australia in which large sequential bedding planes (over hundreds of squaremeters) can be excavated.The fieldwork protocol involves excavation and re-assembly of beds that have beencarefully logged in stratigraphic succession. These bedding-planes will be examined in detail andall body and trace fossils and sedimentary structures recorded and categorized with respect toproperties and nature of preservation. The distribution of fossils is then analysed by standardstatistical methods. Preliminary examination suggests that there is an unexpected high differencein fossils and the nature of bedding planes between beds in immediate stratigraphic succession.An important aim of the project is to explain these observations; to what extent do thesedifferences represent preservational biases or complex communities?An important part of this project is to document in detail trace fossils as well as thenumerous problematic structures of both inorganic and organic origin. Previously there has beenno detailed examination of the distribution of late Proterozoic trace fossils with respect to bodyfossils and the nature of the beds on which the traces occur. The record of late Proterozoic tracefossils is problematic because of numerous misidentifications with problematic structures. Theseproblematic structures have largely been ignored in studies focussed on discrete body fossils, butthey hold important information on the nature of these communities. It is only by examination oflarge bedding plane surfaces that the nature of these objects can be understood and we canultimately understand the taphonomic overprint on Ediacaran assemblages and thus, unravelEdiacaran ecology.Broader ImpactEdiacaran assemblages are the oldest diverse macroscopic fossil assemblages on Earth.As such, they are of considerable interest to a wide range of geologists and biologists. Beddingplanes that will be excavated for this study will be reassembled in a manner that allows for thedevelopment of a site for students and other interested parties to visit (as previously arrangedwith the landowner).This project is ideally suited for undergraduate participation and monies are budgeted for2 undergraduates to travel to Australia and work in the field. Local Australians will also beinvolved with the excavation and related activities. In this way, the significance of this depositand others like it can be conveyed. This project will develop and protect a world class fossillocality the full potential of which has remained untapped.