Why might larger diatoms outlive smaller chalky nannoplankton in K-Pg seas?

Answer: Lower-light lifestyle

Lower-light lifestyle ✓ — Lower-light lifestyle is the point. The 2026 paper notes that smaller nannoplankton could die while larger diatoms survived, so size alone cannot explain every phytoplankton outcome. Diatoms and dinoflagellates tolerate lower-light, turbulent settings better than high-light calcifiers, which flips the usual 'smaller wins' intuition.

Heavier chalk armor — Heavier chalk armor would describe calcifying nannoplankton, not diatoms, which build silica frustules. More importantly, armor does not feed a cell during impact darkness. The odd survival pattern shows why one rule is not enough: small body size helped broadly, but light demand and habitat could overrule it.

Warmer shallow reefs — Warmer shallow reefs do not explain open-ocean diatom survival. Reef-like warmth would be a local habitat story, while the evidence is about global plankton traits. The transfer lesson is that ecology often beats a single measurement: a larger organism can survive if its lifestyle matches the new constraint.