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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

The Ediacara Member of the Rawnsley Quartzite in the Flinders Ranges (South Australia) has undergone considerable investigation due to its placement within the package of terminal Ediacaran sediments in the region and as the host sediments of the Ediacara biota fossils. A focus on palaeoenvironment reconstruction and taphonomy has seen a succession of lithofacies models presented. These have evolved with the expansion of recognised Ediacara biota localities and prevailing palaeontological methodologies. Much of the recent descriptive lithofacies work has focused on the Nilpena fossil site in the west of the Flinders Ranges. This location is particularly fossil-rich but does not represent a "typical" section through the Ediacara Member. The Ediacara Member elsewhere in the region contains up to six parasequences with total thicknesses varying from ten to 260 m. With the exclusion of the Ikara-Chace Range region, the majority of studied locations external to Nilpena do not show clear evidence for significant (canyon-scale), intra-member erosional features. In this study we review existing facies models for the Ediacara Member and compile a "best-fit" revised facies model by incorporating the modern facies interpretations (largely based at Nilpena) and previous basin-wide observations, models and stratigraphic sections. The revised model is assessed against a series of newly measured stratigraphic sections from across the basin. We propose the division of the wave-base facies into two facies, representative of the upper and lower storm wave-base environments respectively and the re-inclusion of a facies representative of a shoreface palaeoenvironment. Additional characters and identifiers for the facies have been incorporated to aid field identification, as the ability to identify facies of fossil-bearing isolated hand-specimens can allow fossils found on scree slopes to be traced back to source beds. Likewise, palaeoenvironmental interpretations are critical to the reconstruction of Ediacara biota habitat and preservational environments. Refereed/Peer-reviewed

Despite 70 years of study, Dickinsonia remains one of the Ediacara biota’s most enigmatic taxa with both morphological characters and phylogenetic affinities still debated. A large population of relatively small Dickinsonia costata present on a semi-contiguous surface from the Crisp Gorge fossil locality in the Flinders Ranges (South Australia) provides an opportunity to investigate this taxon in its juvenile form. This population supports earlier findings that suggest D. costata’s early growth was isometric, based on the relationship between measured variables of length and width. The number of body units increases with length, but at a decreasing rate. A correlation between a previously described physical feature, present as a shrinkage rim partially surrounding some specimens and a novel, raised lip in some specimens, suggests that both features may have been the result of a physical contraction in response to the burial process, rather than due to a gradual loss of mass during early diagenesis. A marked protuberance in 15% of the population is also noted in limited specimens within the South Australian Museum collections and appears to be present only in juvenile D. costata. Both the abundance and narrow size range of this population support the notion that Dickinsonia was a hardy opportunist, capable of rapid establishment and growth on relatively immature textured organic-mat substrates.

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