Total biomass actually peaked 540 million years ago, at the end of the Proterozoic era. See Figure 2 (on page 88) in Franck et al.: Causes and timing of future

Total biomass actually peaked 540 million years ago, at the end of the Proterozoic era. See Figure 2 (on page 88) in Franck et al.: Causes and timing of future biosphere extinctions. Link: https://www.biogeosciences.net/3/85/2006/bg-3-85-2006.pdf https://www.biogeosciences.net/3/85/2006/bg-3-85-2006.pdf