BIOLOGICAL AND ECOLOGICAL INSIGHTS FROM THE PRESERVATIONAL VARIABILITY OF FUNISIA DOROTHEA, EDIACARA MEMBER, SOUTH AUSTRALIA

Abstract

ABSTRACT The Ediacara Biota represents a turning point in the evolution of life on Earth, signifying the transition from single celled organisms to complex, community-forming macrobiota. The exceptional fossil record of the soft-bodied Ediacara Biota provides critical insight into the nature of this transition and into ecosystem dynamics leading up to the so-called “Cambrian Explosion”. However, the preservation of non-biomineralizing organisms in a diversity of lithologies goes hand-in-hand with considerable taphonomic complexity that often shrouds true paleoecological and paleobiological signatures. We address the nature of this taphonomic complexity within the fossiliferous sandstones of the Ediacara Member in South Australia. Utilizing the most fossiliferous outcropping of the Ediacara Member, located at the Nilpena Station National Heritage Ediacara Fossil Site, we conduct a focused, taxon-level biostratinomic characterization of the tubular organism Funisia dorothea. Funisia is the most abundant body fossil in the Ediacara Member, making the characterization of its preservational variability essential to the accurate interpretation of regional paleobiology and paleoecology. We describe remarkable biostratinomic complexity in all Funisia populations at Nilpena, identifying four distinct preservational variants of internal and external molds and four additional successive biostratinomic grades corresponding to loss of external characters. Synthesis of these observations identify the most robust preservational forms of Funisia for use in paleobiological interpretation and highlight the important impact that Funisia's high abundance had on regional paleoecology and on population-scale preservation in the Ediacara Member.