Abstract The large, enigmatic members of the Ediacaran biota have received much attention regarding their possible affinities and mode of life. Fossil evidence reveals that many Ediacaran animals, such as the rangeomorphs, were characterized by extensive surface areas, lived in close association with the seafloor and were non-motile. We argue for the presence of a simple, diploblastic body plan in these early animals and discuss the means by which they probably derived nutrients from chemosynthetic bacteria thriving at the sediment–water interface. We consider that the large surface area of some Ediacaran organisms in the Avalonian biota may have been an adaptation for maximizing a phagocytotic or chemosymbiotic surface. Ediacaran animals probably increased the availability of oxygen along their ventral surface either by diffusion or ciliary pumping. This increased supply of oxygen to the sediment is inferred to have simultaneously increased the productivity of their food source (chemosynthetic bacteria) and restricted the build-up of toxic sulphides in the pore waters below their bodies. This is an example of a very simple form of ecosystem engineering. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license .

Abstract Fossil assemblages from Newfoundland’s Avalon Peninsula preserve diverse examples of the enigmatic Ediacaran macrobiota, offering some of the earliest evidence for large and complex multicellular life. These fossils are exposed on extensive coastal bedding planes in extraordinary abundances, permitting palaeoecological studies based on census data from spatially extensive palaeocommunities. Such studies have been used to constrain the reproductive strategy and phylogenetic placement of Ediacaran organisms. Geological mapping and stratigraphic correlation in the Mistaken Point Ecological Reserve reveal that some fossil-bearing surfaces can be tracked over distances of several kilometres. These laterally extensive surfaces reveal that the modern processes by which the sediment overlying a fossil surface is removed may impose important controls on the observed composition of fossil assemblages. Weathering and erosion – along with factors associated with tectonics, metamorphism and discovery – are here grouped as ‘post-fossilization processes’ and introduce biases that are often not explicitly accounted for in palaeoecological studies. Specifically, post-fossilization processes may differentially influence the preservational fidelity of individual specimens on a given surface and generate features that could be mistaken for original morphological characters. We therefore recommend that post-fossilization processes must be considered when undertaking palaeoecological studies in Ediacaran successions in Newfoundland and, potentially, elsewhere. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license .