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

元古宙末期埃迪卡拉生物群至今仍是现代古生物学中最具争议的问题之一。它的时间位置，在所谓的寒武纪大爆发之前，表明它应该提供关于动物早期进化的关键信息。埃迪卡拉生物群的研究传统上集中在描述和解释的个体taxa和最近的地层分布和古地理。埃迪卡拉生物群研究的一个主要缺点是缺乏群落结构和群落生态学其他方面的研究。元古宙晚期的生物组合不应该用与中生代生物群落相同的方法来研究，这是没有先验的理由的。特别是埃迪卡拉化石保存模型（Gehling 1999）预测它们可能会产生普查群落。拟议的研究项目将是第一个详细的系统性实地分析的高多样性埃迪卡拉组合（包括所有的身体和痕迹化石，通过对南澳地区的研究，发现了一些有问题的结构和无机表面，（超过数百平方米）可以挖掘。现场工作协议包括挖掘和重新在地层序列中被仔细记录的地层的集合。这些层面将被详细检查，所有的身体和痕迹化石和沉积结构记录和分类的性质和保存的性质。然后用标准的统计方法分析化石的分布。初步研究表明，在直接的地层序列中，各层之间的化石和层面性质存在着意想不到的高度差异。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民族偏见或复杂的群落？该项目的一个重要部分是详细记录遗迹化石以及无机和有机起源的复杂问题结构。以前没有详细的研究晚元古代遗迹化石的分布与身体化石和地层的性质，其上的痕迹出现。晚元古代遗迹化石的记录是有问题的，因为许多错误的鉴定与有问题的结构。这些有问题的结构在专注于离散身体化石的研究中基本上被忽视了，但它们包含了这些社区性质的重要信息。只有通过对大型层面表面的研究，才能理解这些物体的性质，我们才能最终理解埃迪卡拉组合上的埋藏叠加，从而揭开埃迪卡拉生态学的面纱。更广泛的影响埃迪卡拉组合是地球上最古老的、多样的宏观化石组合。因此，它们引起了广泛的地质学家和生物学家的极大兴趣。将为这项研究挖掘的层面将被重新组装的方式，允许一个网站的发展，为学生和其他感兴趣的各方参观（如先前与土地所有者）。这个项目是理想的适合本科生参与和资金预算为2本科生前往澳大利亚和在外地工作。澳大利亚当地人也将参与挖掘和相关活动。通过这种方式，可以传达这个矿床和其他类似矿床的重要性。该项目将开发和保护一个世界级的化石地点，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.