Late Campanian nostoceratid ammonites from the Lehrte West Syncline near Hannover, northern Germany

Abstract

The nostoceratid ammonites Nostoceras (Didymoceras) postremum (BLASZKIEWICZ, 1980) and Nostoceras (Didymoceras) varium (BLASZKIEWICZ, 1980) are described from northern Germany for the first time. They appear with the second occurrence of Nostoceras (Bostrychoceras) polyplocum (ROEMER, 1841) in the upper portion of the Neancyloceras bipunctatum / Galerites roemeri Zone of the Lehrte West Syncline (Lower Saxony, east of Hannover), which is equivalent to the upper Belemnitella langei Zone of the chalk of Lägerdorf-Kronsmoor (c. 50 km north of Hamburg). In northern Germany, this ammonite association appears c. 1 Ma earlier than Belemnella lanceolata, which marks the base of the Maastrichtian in belemnite terms, and c. 1.5 Ma earlier than the international base according to the first occurrences of Diplomoceras cylindraceum and Pachydiscus neubergicus at Lägerdorf-Kronsmoor. Assuming that the GSSP of the base of the Maastrichtian Stage at Tercis (southern France) equals the boundary of the U.S. Western Interior (radiometric age 71.3 ± 0.5 Ma), Nostoceras (Bostrychoceras) polyplocum first appears in Europe c. 75 Ma before present.