A geologically rapid Neoproterozoic oxygenation event is commonly linked to the appearance of marine animal groups in the fossil record. However, there is still debate about what evidence from the sedimentary geochemical record—if any—provides strong support for a persistent shift in surface oxygen immediately preceding the rise of animals. In this article, a team of researchers, including School of Earth and Atmospheric Sciences Postdoctoral Scholar Devon Cole, combined approaches from statistical learning, biogeochemical modeling and ecophysiology to better constrain changes in global ocean biogeochemistry and marine animal habitats through the Neoproterozoic and Palaeozoic eras.