Global marine redox changes drove the rise and fall of the Ediacara biota

Feifei Zhang, Shuhai Xiao, Stephen J. Romaniello, Dalton Hardisty, Chao Li, Victor Melezhik, Boris Pokrovsky, Meng Cheng, Wei Shi, Timothy M. Lenton, Ariel D. Anbar

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


The role of O2 in the evolution of early animals, as represented by some members of the Ediacara biota, has been heavily debated because current geochemical evidence paints a conflicting picture regarding global marine O2 levels during key intervals of the rise and fall of the Ediacara biota. Fossil evidence indicates that the diversification the Ediacara biota occurred during or shortly after the Ediacaran Shuram negative C-isotope Excursion (SE), which is often interpreted to reflect ocean oxygenation. However, there is conflicting evidence regarding ocean oxygen levels during the SE and the middle Ediacaran Period. To help resolve this debate, we examined U isotope variations (δ238U) in three carbonate sections from South China, Siberia, and USA that record the SE. The δ238U data from all three sections are in excellent agreement and reveal the largest positive shift in δ238U ever reported in the geologic record (from ~ −0.74‰ to ~ −0.26‰). Quantitative modeling of these data suggests that the global ocean switched from a largely anoxic state (26%–100% of the seafloor overlain by anoxic waters) to near-modern levels of ocean oxygenation during the SE. This episode of ocean oxygenation is broadly coincident with the rise of the Ediacara biota. Following this initial radiation, the Ediacara biota persisted until the terminal Ediacaran period, when recently published U isotope data indicate a return to more widespread ocean anoxia. Taken together, it appears that global marine redox changes drove the rise and fall of the Ediacara biota.

Original languageEnglish (US)
Pages (from-to)594-610
Number of pages17
Issue number6
StatePublished - Nov 1 2019


  • Neoproterozoic
  • Shuram negative carbon isotope excursion
  • early animals
  • ocean oxygenation
  • uranium isotopes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • General Environmental Science
  • General Earth and Planetary Sciences


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