The architecture of Ediacaran Fronds

Ongoing discoveries of new rangeomorph fossils from the Ediacaran of Avalonia allow us to put forward a unified and approachable scheme for the description and phylogenetic analysis of frondose genera and their species. This scheme focuses upon the branching morphology of rangeomorph units. Our system has the advantage of being applicable at all visible scales of subdivision and is suitable for the study of isolated fragmentary specimens. The system is also free from hypothesis about biological affinity and avoids tectonically influenced features such as shape metrics. Using a set of twelve character states within this unified scheme, we here present emended diagnoses for Beothukis, Avalofractus, Bradgatia, Hapsidophyllas, Fractofusus, Trepassia and Charnia, together with a more extensive taxonomic treatment of the latter genus. For those forms that fall within the morphological spectrum between Trepassia and Beothukis, we introduce Vinlandia gen. nov. It is hoped that this scheme will provide a robust framework for future studies of rangeomorph ontogeny and evolution.