Title: Evidence for ammonite survival into the Danian (Paleogene) from the Cerithium Limestone at Stevns Klint, Denmark
Abstract: Two ammonite species, Baculites vertebralis and Hoploscaphites constrictus, are recorded from the Cerithium Limestone (lower Danian, Paleogene) at Stevns Klint, Denmark. Most of the specimens represent internal and external moulds of shell fragments, the sole exception being a complete, well preserved internal mould of H. constrictus. The infilling of the body chamber and phragmocone of this specimen is indistinguishable from the surrounding limestone. The ð13C value for the phragmocone fill is 1.382, matching Danian values much better than the more positive Maastrichtian values for the fine-fraction ð13C curve of the Stevns Klint succession. Additionally, the phragmocone infill contains Operculodinella operculata, a calcareous dinocyst typical of the Danian at high latitudes. The specimen is thus interpreted to be an indigenous early Danian ammonite. In view of the mass occurrence of calcitic bryozoans, brachiopods, and bivalves in the topmost Maastrichtian chalk at Stevns Klint, the total absence of brachiopods and near-absence of bryozoans and calcitic bivalves in the Cerithium Limestone provide evidence against significant redeposition of Maastrichtian fossils into the latter unit. Consequently, all ammonites from the Cerithium Limestone studied are interpreted as early Danian survivors.