The Ediacaran‐Cambrian Transition

Ediacaran oceans hosted a strange world of exotic soft‐bodied forms that were a failed early evolutionary experiment in macroscopic life. These enigmatic organisms appear suddenly in sedimentary rocks as old as 573 Ma above a glacial diamictite in Newfoundland, and, in most successions, a profound and equally puzzling negative carbon cycle anomaly known as the Shuram excursion. The Ediacaran biota died out near the Ediacaran‐Cambrian boundary (<541 Ma) coincident with a second strong negative δ13C excursion. From Ediacaran ashes, the proliferation of complex feeding traces, soft‐bodied arthropod tracks, and mineralized skeletons in the succeeding Fortunian stage led to a diverse landscape of modern phyla by the detonation of the Cambrian explosion around 529 Ma. This chapter provides a review of the profound changes in the carbon, sulfur, and strontium cycles across this critical transition in order to better understand the redox history of the oceans, as well as the tectonic, climatic, and biological events preserved in its sedimentary archive, and further proposes a novel resource‐based hypothesis for the rise and fall of the Ediacaran biota.