Paleoecology of Late Cretaceous Coccolithophores: Insights From the Shallow?Marine Record

Coccolithophores, common primary producers in Mesozoic, Cenozoic, and present oceans, are significant components of the earth’s biogeochemical cycles. Being most productive calcifying organism on earth, their carbonate oozes play a major role fixing CO2, thereby forming important long-term CO2 sink throughout last 100 Ma. Our understanding fossil ancestors is mainly based data from chalk sequences. Generally, Cretaceous chalks were deposited at water depths ?200 m under stable, pelagic conditions. Here we report remarkably diverse coccolithophore assemblages Cenomanian-Campanian (100-72 Ma) nearshore deposits, with estimated ?40 m. For interpreting findings broader paleoenvironmental context, additionally analyzed contemporaneous material Santonian-Campanian (86-72 interval. Highly associations (50–81 species/sample) characterize setting, while samples less (43–54 species/sample). The absolute abundances coccoliths setting by factor 2–10 lower than those chalk, diversity indices 20%–30% higher (Shannon Index = 2.94–3.46) sediments. presence highly communities settings provides new insights into paleoecology evolution paleoceanography Late Cretaceous. revise traditional view coccolithophores being typical open ocean dwellers. Extreme greenhouse world characterized environmental conditions equating hemipelagic realm but supplying larger variety ecological niches.