Mobility of Ediacaran organisms: A review

The Ediacaran Period was a time when life got big with confirmed fossils of megascopic algae, lichens, sponges, and worms. But which of these kinds of organisms are the most likely biological affinities for enigmatic vendobionts such as Dickinsonia ? These iconic quilted organisms have no clear modern relatives, but interpretation as animals has been based in part on putative evidence that they could move of their own accord. These supposed trace fossils of vendobionts, including ‘footprints’ and ‘feeding traces’, are reexamined here for Dickinsonia, Quaestio , and Kimberella . Supposed footprints are more likely tool marks of specimens displaced by wind or water on melting ice, and feeding traces are more likely bundles of ice crystals formed from supercooled water within cavities. Funisia was a sessile creature thought to be able to wave about within the water column, but confinement of the fossils to thin layers is evidence that it was prostrate on the ground. Dickinsonia, Quaestio, Kimberella, and Funisia are found in rocks with sedimentological, petrographic, and geochemical evidence of soil formation, and may have been sessile lichens of Ediacaran terrestrial communities.