Calcareous nannoplankton are photosynthetic plankton producing micrometric calcite platelets having a fossil record covering the past 200 Myr. Based on species richness, platelets size and abundance we observed four evolution phases through time: Jurassic–Early Cretaceous invasion phase of the open ocean, Early Cretaceous–K–Pg extinction specialization phase to the ecological niches, post-K–Pg mass extinction recovery and Eocene–Neogene establishment phase with domination of a few small species.