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Late Campanian and Early Maastrichtian ammonites from the white chalk of Kronsmoor (northern Germany) - taxonomy and stratigraphy

Niebuhr B., Esser K.

Acta Geologica Polonica

2003

Vol. 53, nr 4

257-281

Hypophylloceras (Neophylloceras) velledaeforme (Schluter, 1872), Anagaudryceras lueneburgense (SCHLUTER, 1872), Saghalinites wrighti BIRKELUND, 1965, Pachydiscus (Pachydiscus) neubergicus (VON HAUER, 1858), Menuites cf. wittekindi (SCHLUTER, 1872), Diplomoceras cylindraceum (DEFRANCE, 1816), Baculites vertebralis LAMARCK, 1801, Baculites knorrianus DESMAREST, 1817, Acanthoscaphites tridens (KNER, 1848), and Hoploscaphites constrictus (J. SOWERBY, 1877) are described for the first time from Kronsmoor, the only continuous Campanian-Maastrichtian boundary succession of northern Germany. Combined with the slightly younger section at Hemmoor (30 km SW of Kronsmoor), thirteen ammonites species in all are known to date from the Maastrichtian. The material studied comprises species from the Upper Campanian Belemnitella langei to the Lower Maastrichtian Belemnella sumensis zones. Three species (Baculites vertebralis, Baculites knorrianus, Hoploscaphites constrictus) occur earlier here than elseswhere (e.g. Denmark). Menuites cf. wittekindi, formerly known only from the Nostoceras polyplocum Zone (Upper Campanian), occurs in the Belemnella lanceolata Zone at Kronsmoor. Pachydiscus neubergicus and Diplomoceras cylindraceum, two of twelve markers for the base of the Maastrichtian at Tercis (GSSP, southwestern France), have their first occurrences at Kronsmoor significantly above that of Belemnella lanceolata, the belemnite marker for the base of the stage. Compared with Tercis, were the stage boundary was recommended between the FOs of both ammonite species, the Campanian - Maastrichtian boundary at Kronsmoor seems to be located within the Belemnella pseudobtusa Zone. Thus, the first occurrence of the genus Belemnella is of Late Campanian age, appearing c. 540 ky earlier than the base of Maastrichtian as defined at the GSSP at Tercis.