The terminal Proterozoic Ediacaran biota remains one of the great controversies in modern 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 the Ediacaran biota have traditionally focussed on the description and interpretation of individual taxa and more recently on the stratigraphic distribution and paleogeography. A major shortcoming in the study of the Ediacaran biota is the paucity of studies of the community structure and other aspects of synecology. There is no a priori reason why late Proterozoic assemblages should not be examined by the same means as Phanerozoic communities. Particularly as models for the preservation of Ediacaran fossils (Gehling 1999) predict that they potentially should yield census communities. The proposed research project will be the first detailed systematic field analysis of a high-diversity Ediacaran assemblage (including all body and trace fossils, problematic structures and inorganic surfacesls) by the study of selected localities in South Australia in which large sequential bedding planes (over hundreds of square meters) can be excavated. The fieldwork protocol involves excavation and re-assembly of beds that have been carefully logged in stratigraphic succession. These bedding-planes will be examined in detail and all body and trace fossils and sedimentary structures recorded and categorized with respect to properties and nature of preservation. The distribution of fossils is then analysed by standard statistical methods. Preliminary examination suggests that there is an unexpected high difference in 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 these differences represent preservational biases or complex communities? An important part of this project is to document in detail trace fossils as well as the numerous problematic structures of both inorganic and organic origin. Previously there has been no detailed examination of the distribution of late Proterozoic trace fossils with respect to body fossils and the nature of the beds on which the traces occur. The record of late Proterozoic trace fossils is problematic because of numerous misidentifications with problematic structures. These problematic structures have largely been ignored in studies focussed on discrete body fossils, but they hold important information on the nature of these communities. It is only by examination of large bedding plane surfaces that the nature of these objects can be understood and we can ultimately understand the taphonomic overprint on Ediacaran assemblages and thus, unravel Ediacaran ecology. Broader Impact Ediacaran 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. Bedding planes that will be excavated for this study will be reassembled in a manner that allows for the development of a site for students and other interested parties to visit (as previously arranged with the landowner). This project is ideally suited for undergraduate participation and monies are budgeted for 2 undergraduates to travel to Australia and work in the field. Local Australians will also be involved with the excavation and related activities. In this way, the significance of this deposit and others like it can be conveyed. This project will develop and protect a world class fossil locality the full potential of which has remained untapped.
