Chronology of Ediacaran sedimentary and biogeochemical shifts along eastern Gondwanan margins

Abstract

Determining causal relationships between environmental change and early animal evolution has been limited by our lack of a robust temporal framework for the Ediacaran Period (635-539 million years ago). Here we present six new radioisotopic age constraints from the Sultanate of Oman, which furnish a quantitative temporal framework for biogeochemical changes associated with animal radiation in the middle and late Ediacaran Period. In addition to constraining the duration of Earth’s largest negative carbon isotope excursion in its type locality, this temporal framework underpins a new understanding of Ediacaran sedimentation rates, a critical control on geochemical records and fossil preservation. Our new dates quantify early Ediacaran (prior to c. 574 million years ago) condensation in key sections across Gondwanan margins. This temporal framework highlights a pressing need to reassess proxy records of oxygenation—often hypothesized as a critical environmental constraint for the emergence of complex multicellular life—considering non-static sedimentation rates.