How diverse were early animal communities? An example from Ediacara Conservation Park, Flinders Ranges, South Australia

Abstract

Fossils of the Ediacara biota record the earliest evidence of animal communities and, as such, provide an invaluable glimpse into the abiotic and biotic processes that helped shape the evolution of complex life on Earth. A diverse community of Ediacaran macro-organisms is preserved with high resolution in a fossil bed recently excavated from north Ediacara Conservation Park (NECP) in the Flinders Ranges, South Australia. Many of the commonly described Ediacaran taxa from the Flinders Ranges are represented on the bed surface and include: Parvancorina, Rugoconites, Spriggina, Dickinsonia, Tribrachidium, Kimberella, Charniodiscus and Yorgia, including two new taxa. Numerous additional fossil-bed fragments from the same locality were analysed that preserve a similar suite of taxa and shared sedimentology. On all surfaces, preserved microbial mat appeared complex, both in topography and in texture, and the unique combination of fine grainsize, high diversity and trace fossils provide insights into the palaeoecology of the ancient organisms that lived during the Ediacaran Period some 550 Ma. Several trace fossils are overlapped by body fossils, indicative of successive events, and complex organismal behaviour. The complexity of this fossil surface suggests that the primordial community was relatively mature and possibly at late-stage succession.