Biomarker 8: Cenosphaera sp FDO
Found in the Mackerel Formation of the Central North Sea and in the lower Jukes Formation in the Southern North Sea (Latest Santonian, top testudinarius to basal pilula zones). Species of Gavelinella, Reussella and Stensioeina (including S granulata perfecta and S. exsculpta exsculpta) also occur in some parts of the North Sea Basin. The biomarker was used in order to link the Northern, Central and Southern North Sea basins, but in the southern North Sea, a better biomarker is the FDO of Stensioeina exsculpta exsculpta in the very basal pilula macrofaunal zone.
Correlation: This biomarker has not been defined onshore, but based on the FDOs of the species of Stensioeina, it can be placed at or close to the top of BGS foraminiferal Biozone 18 (Wilkinson, 2000).