Dickinsonia

Lore & Background

Dickinsonia was first discovered in 1946 at the Ediacara Member of the Rawnsley Quartzite, Flinders Ranges in South Australia. Reg Sprigg described it the following year, naming it after Ben Dickinson, then Director of Mines for South Australia. Sprigg initially interpreted it as a jellyfish-like organism from the early Cambrian. Later, after the discovery of Precambrian Charnia in 1958, Dickinsonia was recognized as Precambrian in age. It has since been found in Ukraine, Russia, and China.

Reader's Guide

Dickinsonia is significant as a key member of the Ediacaran biota, representing some of the earliest complex multicellular life. Its classification has been heavily debated: initially thought a jellyfish, later proposed as an annelid, lichen, placozoan, giant protist, or stem-group bilaterian. The discovery of cholesterol in Russian specimens in 2018 supported an animal affinity, though this has been questioned. Its segmented body, with disputed glide reflection or true bilateral symmetry, and lack of mouth, anus, and gut, suggest it was not a crown-bilaterian but possibly a stem-bilaterian. Dickinsonia-shaped trace fossils (Epibaion) indicate it was mobile and fed on microbial mats. Its preservation as imprints and casts, sometimes in large beds at Nilpena Ediacara National Park, provides insight into Ediacaran taphonomy and ecology.

Did You Know?

• Dickinsonia could range from a few millimeters to about 1.4 meters in length.
• It is disputed whether its segments are bilaterally symmetric or offset via glide reflection.
• Deformed specimens from Russia indicate Dickinsonia could regenerate after being damaged.
• Dickinsonia-shaped trace fossils, assigned to the genus Epibaion, are sometimes found in chains suggesting feeding behavior.