Viewing the Ediacaran biota as a failed experiment is unhelpful

Macroscopic organisms from the late Ediacaran period have often been described as failed experiments in the history of life. We argue that the field of Ediacaran palaeobiology should dispense with unhelpful historical classification schemes and embrace phylogenetic systematics if we are to establish the evolutionary relevance of these fossils. The Ediacaran macrobiota — an assortment of macroscopic, largely soft-bodied organisms that lived during the ~30 Myr interval prior to the Cambrian period — have long been considered a palaeontological conundrum. Many fossils of these organisms exhibit unusual body plans that are unlike anything seen among living taxa (Fig. 1a–d) and it has proved difficult to resolve their relationships to extant groups. Individually and collectively, members of the Ediacaran macrobiota have been both allied with extant clades and deliberately set apart from them by suggestions that they were either ‘failed experiments’ in the history of life, or members of long-extinct higher-order clades1. Despite the role they have played in stimulating debate around these taxa, we argue that these latter viewpoints have hampered Ediacaran research. They have also created confusion within the wider community as to the placement of the Ediacaran macrobiota in the tree of life, forming a barrier to their incorporation within biological and developmental discussions. We advocate abandoning the failed experiment perspective and embracing phylogenetic thinking in order to make progress in determining the phylogenetic positions of these organisms and realizing their evolutionary significance