Chalk Biozone 2 - Epelidosphaeridia spinosa
Age: Earliest Cenomanian to mid Cenomanian.
Macrofaunal correlation: The M. dixoni Zone to the A jukesbrownei Zone.
Definition: The interval between the LAD of Ovoidinium verrucosum subsp. verrucosum to the LAD of Epelidosphaeridia spinosa.
Comments: The LAD of Epelidosphaeridia spinosa is a well established marker for the mid Cenomanian (Foucher, 1981; Marshall, 1983; Costa & Davey, 1992; Foucher & Monteil, 1998). This bioevent may occur within the A. jukesbrownei Zone, however the top of this Biozone is delienated at the A jukesbrownei Zone-C. guerangeri Zone boundary. An alternative index for the top of this Biozone is the FAD of Florentinia ferox (see Foucher, 1981). The FAD of Apteodinium deflandrei occurs within this Biozone, at the base of the A. rhotomagense Zone (Foucher, 1981).
Lithostratigraphical correlation: The upper West Melbury Marly Chalk and the lower Zig Zag Chalk formations (Southern Province), the Ferriby Chalk Formation (Northern Province) and the Hidra Formation (North Sea).