2008 Joint Annual Meeting (5-9 Oct. 2008): Did Ediacaran fossils live on land?

Neoproterozoic (550 Ma) impression fossils from the Ediacara Hills, and nearby Flinders Ranges of South Australia, have been regarded as obligate marine creatures, such as echinoderms or xenophyophores. Reinterpretation as extinct Vendobionta, or as fungi or lichens, opens the possibility of non-marine habitats. Non-marine habitats are compatible with occurrence of Ediacaran impression fossils in different South Australian formations and facies than acritarchs, stromatolites, and other aquatic and marine indicators. Red beds with Ediacaran fossils are highly oxidized, and have the poorly sorted, highly angular, silt-size grains of loess. The red beds contain desiccation cracks, sand crystals, ice cracks, chemical alteration and periglacial involutions diagnostic of soil formation. Fossil soils (paleosols) directly below Ediacaran fossils include chemically weathered, clay-enriched and ferruginized upper horizons, and subsurface horizons of sand-crystals and nodules pseudomorphous after gypsum. Ediacaran fossils including Dickinsonia, Parvancorina, Charniodiscus and Tribrachidium are preserved in life position within rocks interpreted as surfaces of unfrozen, low salinity and well drained soils of floodplains or tidal flats in an arid, cold temperate climate.