BGS Zone 11 (=lower and middle UKB10 of Hart et al., 1989)
Base: Inception of Marginotruncana pseudolinneiana.
Top: Inception of Marginotruncana coronata.
- The extinction of Globigerinoides bentonensis is at the basal boundary of the zone.
Subzones: The extinction of Marginotruncana sigali takes place in the lower part of the zone (middle T. lata macrofaunal zone). The concurrent range of that species with Marginotruncana pseudolinneiana is considered to be of subzonal significance. The upper part of the zone, which lacks M. sigali, is characterised by agglutinating species such as Labyrinthidoma (= Coskinophragma, sp., G. laevigata and S. praelongata.
Macrofaunal correlation: middle to upper T. lata Zone.