With the success of the end-Cretaceous bolide hypothesis, there was a movement in some circles to explain mass extinctions with bolide events, . If bolide events were responsible for all mass extinctions, then the , galactic explanation might still have relevance. Even though an end-Permian bolide event was unveiled with great fanfare and media attention in 2001, it does not appear to be a valid extinction hypothesis today, and invoking bolide impacts to explain mass extinction seems to have been a passing fad that has seen its best days. The oxygen hypothesis for explaining extinctions, evolutionary novelty, and radiations is similarly called a current fashion in some circles, and time will tell how the hypothesis fares, although it seems to have impressive explanatory value.
In this study,we use ~ 500 depth-integrated field measurements of NF covering thePacific and Atlantic oceans to test whether the spatial variance ofthese measurements can be explained by the commonly hypothesizedenvironmental controls, including measurement-based surface solarradiation, mixed layer depth, average solar radiation in the mixedlayer, sea surface temperature, wind speed, surface nitrate andphosphate concentrations, surface excess phosphate(P*) concentration and subsurface minimum dissolvedoxygen (in upper 500 m), as well as model-based P*convergence and atmospheric dust deposition.