Search

The Ediacara Member of the Flinders Ranges (South Australia) preserves body and trace fossils of the Ediacara biota. Fossils span five lithofacies representative of a range of shallow-marine environments and are preserved as in situ and transported material. Previous work has demonstrated a relationship between paleo environment and taxa at the Nilpena fossil site. We expand the analysis to include facies-taxa data from a further nine localities across the Flinders Ranges to assess if the taxa–paleo environment relationship is site specific or valid at a regional scale. The new analysis demonstrates that the distribution of taxa within the lithofacies, as a proxy for paleo environment, is non-random. This preliminary analysis presents a beta diversity-like spatial turnover across the range of shallow marine Ediacaran environments, and demonstrates taxonomic assemblages are specific to given paleo environmental zones. These assemblages are consistent over a broad spatial extent and also a presumed temporal distribution. This specificity indicates that a marked sensitivity to environmental parameters was present in these communities, as demonstrated by the non-random distribution of taxa and spatial turnover of biotic assemblage throughout the gradational environments of the Ediacara Member. This study highlights the variability and heterogeneity that is a characteristic of shallow marine settings, and offers a novel approach to the future investigation of the relationship between Ediacaran environments and taxa assemblages. Refereed/Peer-reviewed

Ediacara fossil surfaces from the Flinders Ranges (South Australia) commonly record excellent preservation quality and can provide a palaeoecological window into some of the oldest communities on Earth (ca. 555 Ma). An excavated semi-contiguous sandstone bed of 6.5 m2 from a fossil locality at Crisp Gorge in the central Flinders Ranges records an abundance of taxa and structures characteristic of White Sea assemblage communities. Stratigraphic analysis places the fossil surface within the Oscillation Rippled Sandstone Facies of the Ediacara Member at Crisp Gorge. The community appears to be predominantly juvenile forms, with Dickinsonia costata, Parvancorina minchami and Tribrachidium heraldicum present only within interpreted juvenile size ranges. The textured organic surface contains structures including low relief ridges and round bosses, but overall records a smooth bed surface and is interpreted as representing a surface with only an immature microbial mat developed before burial. No effaced or decayed organisms were identified. Community analysis describes an intermediate Shannon diversity (1.27) and an uneven community dominated by the population of D. costata, which comprises more than 50% of the individuals. The examined parameters, when combined with the presence of small, juvenile taxa and an immature organic mat, suggests that the community inhabiting this surface prior to its catastrophic burial may have been comparable to a modern early-stage, primary successional community. The Crisp Gorge bed emphasizes that Ediacara fossil surfaces from South Australia span a range of developmental stages and offer a window into Ediacaran sea-floor communities at various stages of maturity. Refereed/Peer-reviewed