a, Compilation of biological evidence (updated from refs 42, 61): key animal traits (red dots); estimated contributions to marine export production inferred from biomarker and microfossil data (the yellow diamond marks the first substantial occurrence of eukaryotic biomarkers44); first appearance of key eukaryotic phenomena, traits and clades (dashed lines indicate more debatable evidence). b, Summary of ocean redox conditions at different depths, updated from ref. 16 (question mark indicates possible interval of intermediate-water euxinia). c, Secular variation in the carbon isotope composition of marine carbonates. d, Strontium isotope composition of sea water. Figure adapted from ref. 57.