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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. Image 1 • Facies of the Ediacara Member represent habitats of the Ediacara biota. • Four facies represent shallow marine and deltaic environments. • Two facies represent deposition of sediment-gravity flow events. • Field ID will aid in locating related fossiliferous beds that are no longer in situ. [ABSTRACT FROM AUTHOR]

The ancient in situ fossil seafloor communities of the Ediacara biota present an unparalleled window into the assembly of the earliest complex macroscopic organisms, including early animals on Earth ca. 555 million years ago (mya). The unique preservation style of Ediacara fossil seafloors preserves whole communities virtually ‘frozen in time’, including both living and dead organisms at the time of burial. This phenomenon, where the fossilized organisms are arranged as they were in life offers an unparalleled opportunity to examine ecological patterns in some of the earliest examples of animal communities in deep time. The small, anchor-shaped fossil genus Parvancorina is common among the Ediacara biota; however, its morphology and ecology have received little attention. Here, we describe a population of juvenile Parvancorina preserved on a section of fossil seafloor recently excavated from the characteristic Ediacara Member from Ediacara Conservation Park in the Flinders Ranges, South Australia. We applied spatial methods to the sample population of Parvancorina ( n = 202) and found that they demonstrated two size-clusters, distinguishing juveniles from adults, and further analyses showed that the smaller specimens tended to be spatially aggregated. For the first time among any Ediacara taxon, we found that this sample population of Parvancorina demonstrated a strong bimodal orientation, suggesting that orientation played an important behavioral role in its autecology. The aggregated spatial distribution and bimodal orientation of Parvancorina likely resulted from behavioral responses to the influence of benthic currents, suggesting that Parvancorina had a complex sensory network, and was capable of motility. [ABSTRACT FROM AUTHOR]

Exceptional fossil deposits exhibiting soft-part preservation, or Konservat-Lagerstätten , are prevalent in Cambrian rocks and provide detailed information on fossil assemblages not available from conventional deposits. It has long been recognised that many of these assemblages exhibit certain taxonomic similarities, with many elements seemingly having cosmopolitan distributions. These types of assemblages, particularly those of Cambrian age, have become known as Burgess Shale-type (BST) biotas, named for the famous deposit in the Canadian Rocky Mountains where fossils preserved in this way were first discovered. This study provides the first broad-scale analysis of the assemblage relationships between all major BST biotas. We compiled a database of the presences and absences of over 600 genera within 12 Lagerstätten from Laurentia, Siberia, South China and East Gondwana, ranging in age from Cambrian Series 2 through Series 3 (late-early to middle Cambrian; c. 518–502 Ma), and analysed this using a variety of quantitative methods in order to investigate the relationships between these sites. Non-metric multidimensional scaling (NMDS) ordination, cluster analysis and Parsimony Analysis of Endemicity (PAE) were used to group localities and examine relationships. We also used Bayesian inference and illustrate the benefits of this approach to biogeographic studies. Results suggest that both space and time have important effects on the taxonomic constitution of BST biotas, and that the similarity of these assemblages appears to increase from Series 2 through Series 3, largely driven by increases in cosmopolitanism of biomineralised taxa such as trilobites and brachiopods. There is also evidence of higher-level taxonomic turnover across this period. Endemic taxa help amplify these patterns, despite their frequent exclusion from biogeographic analyses. [ABSTRACT FROM AUTHOR]

The late Ordovician Tafilalt Biota of Morocco is a recently discovered Konservat-Lagerstätte that provides abundant paropsonemid eldonioids – resembling those from the Cambrian Burgess Shale and Chengjiang biotas, or other paropsonemid occurrences from the Ordovician to Silurian of the US and Australia – large discoidal ?holdfasts, non-biomineralised cheloniellid arthropods, rare vermiform fossils and articulated skeletons of echinoderms and trilobites. Exceptional preservation of soft-bodied organisms occurs in medium- to coarse-grained sandstones, in a style reminiscent of the soft-bodied Ediacaran fossils of the White Sea Assemblage. Here, we describe the first articulated scleritomes of a large palaeoscolecid worm from Africa. In addition to the mineralised sclerites, the specimens also exhibit extensive soft-tissue preservation down to micron-scale, including fine detail of annuli with their plate, platelet and microplate arrangement on a reticulate cuticle. Compression fossils of the new species Gamascolex vanroyi are represented by external moulds with remains of phosphatised cuticular structure, secondarily weathered into strontian crandallite. Partial foregut fossilisation is seen in one specimen, and phosphatised digestive structures are also reported in three co-occurring trilobite genera at the Bou Nemrou locality. From a palaeogeographic point of view, these North African palaeoscolecids represent the highest palaeolatitudinal occurrence of this Palaeozoic group in Gondwana, being described for the first time in cold-water areas adjacent to the Late Ordovician South Pole. It also provides a palaeobiogeographic link to the original distribution of the genus Gamascolex in a central European Peri-Gondwanan terrane. [ABSTRACT FROM AUTHOR]

Abstract: The discovery of new palaeoscolecid material (Cycloneuralia) from the Emu Bay Shale Konservat-Lagerstätte of Kangaroo Island, South Australia (Cambrian Series 2, Stage 4) and from the Murero biota of NE Spain (Cambrian Series 3, Stage 5—Drumian) has prompted a reappraisal of PalaeoscolexWhittard, 1953, the genus to which species from these, and other Cambrian localities, have most recently been assigned. Available data from scanning electron microscopy show the presence of Hadimopanella-type sclerites covering the surface of these taxa, permitting taxonomic schemes based on microfossils and whole-body compression fossils to be reconciled. The sclerite pattern, size and shape indicate that several of the Cambrian species assigned to Palaeoscolex need to be reassigned to WronascolexIvantsov and Zhuravlev, 2005, a genus originally described from Siberia. The studied material includes Wronascolex antiquus (Glaessner, 1979) and Wronascolex iacoborum sp. nov. from Kangaroo Island (Australia) and two new specimens of Wronascolex? from the Iberian Ranges (Spain). SEM examination of the types of Palaeoscolex ratcliffeiRobison, 1969, a Cambrian species from Utah to which Murero material has been compared, suggests that this species should possibly be assigned to Wronascolex. These taxa are also considered in a Cambrian palaeobiogeographic context, together with the presence of isolated Hadimopanella sclerites, showing a distribution of Wronascolex largely confined to palaeotropical environments. [Copyright &y& Elsevier]