View source for BGS Zone 23 (=UKB19 of Hart et al., 1989)

'''Base: '''Inception of ''Bolivinoides draco miliaris'' and ''B. sidestrandensis''.

'''Top: '''Inception of ''Bolivinoides peterssoni''.

'''Biomarkers: '''

* ''Heterohelix complanata'' has its inception at the base of the zone.

* ''Reussella szajnochae szajnochae'' occurs in flood proportion immediately below the Maastrichtian.

* A number of species become extinct at the upper boundary of the foraminifera zone, including ''Reussella szajnochae szajnochae, Neoflabellina rugosa, Gavelinella monterelensis, Globorotalites hiltermanni'' and ''Osangularia cordieriana''.

'''Macrofaunal correlation''': upper ''B. mucronata'' Zone (= Paramoudra Chalk of East Anglia)

'''Age: '''Latest Campanian

[[Category:Foraminiferal zonation | 023]]