TAPHONOMY OF AN ABUNDANT AND WIDESPREAD NEW EDIACARAN TUBULAR FOSSIL; SOMATOHELIX SINUOSUS (EDIACARA MEMBER, SOUTH AUSTRALIA)

A recent rise in work on the description of Neoproterozoic tubular fossils from globally dispersed localities has shown that organisms that utilized a tubular structural organization represent a far greater proportion of Ediacaran diversity and abundance than was previously appreciated. However, this phylogenetically diverse group remains largely undescribed because preservation is commonly poor; unlike many other typical members of the Ediacara Biota, tubular organisms often collapse precluding excellent preservation. The fossil lagerstätten of the Ediacara Member in South Australia contain one of the most diverse fossil assemblages of any occurrence of the Ediacara biota with a portion of that diversity being represented by a currently undescribed or misinterpreted set of fossils of organisms that utilized a tubular constructional morphology. Occurrences of a new morphotype, Somatohelix sinuosus, reveal distinct body fossil traits such as sediment infill, folding, and current alignment. Somatohelix sinuosus appears as wavy casts and molds on the base of beds approximately 2-7 mm wide and 3-14 cm long indicative of a tubular organism which would have had a gradual corkscrew shape standing erect on the seafloor. Over 200 specimens of this new species have currently been recovered from the more than 200 m² of reconstructed bedding surface within the Ediacara Member. The ability to view large quantities of reassembled bedding surface show low taphonomic grade specimens often occurring on the same bedding surface as those few exceptionally preserved specimens, providing insight into different preservational styles of this fossil. In light of the description of the best specimens of Somatohelix sinuosus and identification of taphonomic variants of this newly described constructional morphology, the organism that produced this fossil is believed to have been a widespread and abundant macroscopic element of the Ediacara biota.