Probable benthic macroalgae from the Ediacara Member, South Australia.

• Primary producers are commonly not included in studies of the Ediacara Biota. • Here we describe new taxa that are most likely benthic macroalgae from the Ediacaran of South Australia. • Specimens consist of bundled filaments. • These taxa are similar to those described from China. The Ediacara biota records the rise of morphologically complex macroscopic eukaryotes, including animals and other heterotrophs. Eltonian ecology demands that Ediacaran ecosystems must have been supported by primary producers (e.g., cyanobacteria, phytoplanktonic eukaryotes, benthic macroalgae). But the fossil record of Ediacaran primary producers has not been fully documented, particularly with respect to benthic macroalgae, hampering a complete understanding of Ediacaran ecosystems. Here we provide systematic description of probable benthic macroalgal fossils from the Ediacara Member of the Rawnsley Quartzite at the National Heritage site Nilpena in South Australia. These fossils include Flabellophyton stupendum sp. nov., F. typicum , Liulingitaenia irregularis sp. nov., and Longifuniculum cf. dissolutum. Previously informally referred to as Bundles of Filaments (BOF), they are characterized by bundled filaments that can be twisted, loosened, or otherwise deformed. Although many are fragmented, some specimens of Flabellophyton stupendum sp. nov., F. typicum , and possibly Longifuniculum cf. dissolutum bear structures that resemble variants of Pseudorhizostomites and "mop", but interpreted here as holdfasts, suggesting that in life these were epibenthic organisms attached to the substrate. Atypical populations of relatively small Ediacara-type fossils are found on a bedding surface dominated by benthic macroalgae, suggesting that, together with microbial mats, these primary producers were beneficial for juvenile settlement of Ediacara-type organisms, potentially contributing both oxygen and nutrients. Although debates about animal affinity dominate Ediacaran paleontology, this study highlights the importance of benthic macroalgae in Ediacaran ecosystems. [ABSTRACT FROM AUTHOR]