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Journal of Paleontology 92(3):323–335
food-capturing structures, it is difficult to interpret how food capture was achieved in Arborea. Tiering is presumed to have mostly been achieved through differences in the length of the stem, which would have been significantly sturdier than the petalodium, and may have been a driving force in Ediacaran speciation and evolution (Laflamme et al., 2004; Laflamme et al., 2012).
Conclusions
Newly discovered three-dimensional specimens of Arborea arborea from Nilpena Farm in the Flinders Ranges in South Australia allow for the reinterpretation of the morphology and function of this Ediacaran frond. The bifoliate petalodium and distinct branching morphology allow for Australian specimens of Charniodiscus arboreus to be reassigned to Arborea arborea. Combined with well-preserved two-dimensional speci-
mens, it is possible to isolate the morphological variation asso- ciated with the taphonomic process responsible for the preservation of soft-bodied Ediacara fossils and allow for a reconstruction of Arborea that can account for the variation in morphology between various taphomorphs. Arborea-type branching architecture highlights teardrop-shaped secondary branches on one side of the petalodium that were most likely the primary loci for nutrient absorption. Secondary branches were not attached to one another, which allowed for water to flow between these branches. Since the primary branches were likely stitched together or attached to a sheet, an epifaunal, recumbent life habit is implied for these fronds, allowing water currents to travel along the entire length of the petalodium where secondary branches could have absorbed dissolved organic nutrients directly from the water column.
Acknowledgments
Support to Laflamme was provided by the Natural Sciences and Engineering Research Council of Canada Discovery Grant (RGPIN 435402). Several key specimens were discovered by SA Museum volunteers M. Fuller, D. Rice, C. Armstrong, J. Perry, and S. Lange. Field work was supported by an Australian Research Council Discovery Grant (DP0453393) to Gehling. Excellent reviews were provided by A. Liu and an anonymous reviewer.
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