Ediacaran Textures of Life: The ecological, biological and sedimentological significance of widespread textured organic surfaces in the Ediacara Member, Rawnsley Quartzite, South Australia

-Dr. Mary Droser
University of California, Riverside

In the absence of complex, bioturbating organisms, the seafloor during the Precambrian was covered in widespread organic matgrounds. The greatest diversity and complexity of organic mat textures occur in the Ediacaran (635-539 Ma) fossil record as exemplified by the Ediacara Member of the Rawnsley Quartzite cropping out in and around the Flinders Ranges, South Australia. This succession unambiguously demonstrates that heterogenous mats coexisted with and were central to the ecology and biology of the Ediacara Biota. Thus, this period occupies a critical time in Earth history when we can observe the onset of complex life forms in environments containing ubiquitous mat textures. Distinct sedimentary features indicative of mats are particularly pervasive and distinctive, demonstrating that the organically-stabilized substrate not only mediated community ecology, but also shaped the sedimentology and stratigraphy of Ediacaran successions. Organic binding of sediment inhibited reworking, erosion and amalgamation of similar-textured beds and facilitated preservation of extremely thin beds and ultimately, the capture of a complete sedimentary and stratigraphic record.