The currently defined Global Stratotype Section and Point for the Campanian/Maastrichtian boundary at Tercis (France) lacks any belemnite record. However, the detailed correlation of Tercis with the Kronsmoor section in northern Germany has enabled recognising this boundary in terms of belemnite stratigraphy close to the first appearance datum (FAD) of Belemnella obtusa Schulz, 1979. Originally, the FAD of the genus Belemnella Nowak, 1913 (e.g. of Belemnella lanceolata (von Schlotheim, 1813)) has been widely used for defining the base of the traditionally understood Maastrichtian stage in the Boreal Realm. Belemnella appeared almost contemporaneously across a significant portion of epicontinental Europe in what is now considered topmost Campanian and dominated the lower Maastrichtian belemnite assemblages, co-occurring with Belemnitella d’Orbigny, 1840 and rare Fusiteuthis Kongiel, 1962. It disappeared in Western and Central Europe during the mid-Maastrichtian, and as a consequence, the FAD of Belemnitella junior Nowak, 1913 served as a biomarker defining the base of the upper Maastrichtian substage. It is only at the end of the Maastrichtian that the genus Neobelemnella Naidin, 1975 became abundant, replacing Belemnitella steadily from the east to the west as the dominating species. The factors underlying those remarkable shifts in belemnite assemblages remain uncertain, but various environmental elements, especially water depth and temperature, in addition ocean currents, and oceanic chemical composition are considered influential.

An overview is presented of belemnitellid faunas of Santonian to Maastrichtian (Late Cretaceous) age in the Mons Basin and in the Brabant-Méhaigne and Maastricht-Aachen-Liège areas (Belgium, southeast Netherlands). As many as twenty-two species of the genera Actinocamax Miller, 1823, Gonioteuthis Bayle, 1878, Belemnitella d'Orbigny, 1840 and Belemnella Nowak, 1913 have been recorded to date. On the basis of these, thirteen zones can be distinguished: three in the Santonian (G. w. westfalica, G. westfalicagranulata and G. granulata), six in the Campanian (G. granulataquadrata, G. quadrata, Blt. mucronata, Blt. woodi, Blt. minor I and Blt. minor II) and four in the Maastrichtian (Bln. obtusa, Bln. ex gr. sumensis/cimbrica, Blt. junior and Bln. kazimiroviensis). Correlative schemes between these zones and those proposed for Norfolk (southeast England) and for the combined Lägerdorf-Kronsmoor-Hemmoor section (northern Germany) are presented. The belemnitellid assemblage of the study area closely resembles that of Norfolk, but differs from the late Campanian faunas of northwest Germany.