The last ammonite?

Abstract

A fragment of red-brown flint with imprints of two ammonite aptychi has been found loose on the beach of the Boesdal quarry on Stevns Klint. The quarry exposes only Lower Danian bryozoan limestone. The nearest occurrence of Maastrichtian strata is 400 m to the west in Skeldervig bay, north of Korsnæb, where 50 cm of chalk with small dark-grey and black flint nodules are exposed below the basal Danian Fish Clay over a stretch of 15 m. Maastrichtian chalk is normally dark-grey to black and has a thin white rind. Danian flint is much more variable in colour and degree of silicification, and red-brown varieties are common. The two aptychi clearly belong to the same ammonite individual and cannot have been redeposited from the crests of the top-Maastrichtian mounded bryozoan chalk. Finds of the ammonite Hoploscaphites constrictus and Baculites sp. have been reported in the literature from the lowermost Danian Cerithium Limestone. They are normally considered reworked, but their age should possibly be re-evaluated in the light of the new find. It is thus very likely that two ammonite genera survived the mass extinction at the K-T boundary and lived on as rare elements in the earliest Tertiary fauna.