BGS Zone 12 (=upper UKB10 of Hart et al., 1989)

Base: Inception of Marginotruncana coronata.

Top: Inception of Verneuilina muensteri.

Biomarkers:

• Praeglobotruncana helvetica extinction in the lower part of the foraminiferal zone (upper part of the T. lata macrofaunal zone).

• The top of the interval of common Labyrinthidoma (= Coskinophragma), in the Southerham Marls, Lewes Nodular Chalk of south eastern England, is in the upper part of the T. lata macrofaunal zone.

• The reappearance of Gavelinella tourainensis in the highest T. lata macrofaunal zone.

• 'Dicarinella imbricata in the middle part of the foraminiferal zone (at or little above the base of the S. plana macrofaunal zone).

• Reussella kelleri appears for the first time in the upper part of the foraminiferal zone (lower S. plana macrofaunal zone), immediately above the Bridgewick Marls in the lower Lewes Nodular Chalk Formation of southern England, although it is rare and patchily distributed in the early part of its range.

• Lingulogavelinella arnagerensis appears for the first time in the upper part of the zone (upper part of the S. plana macrofaunal zone) immediately above the Kingston Nodular Chalks in the middle part of the Lewes Nodular Chalk Formation of southern England. It is rare and patchily distributed in the lower part of its range.

Macrofaunal correlation: upper T. lata Zone and S. plana Zone.

Age: Turonian