The stratigraphic range of the index ammonite Pachydiscus neubergicus (von Hauer, 1858) in the type area of the Maastrichtian Stage

Abstract

In the extended type area of the Maastrichtian Stage (southern Limburg, the Netherlands; provinces of Limburg and Liège, Belgium; Aachen area, Germany), the pachydiscid Pachydiscus (P.) neubergicus (von Hauer, 1858) ranks amongst the rarer species of Campanian-Maastrichtian ammonites. To date, just four specimens are known, which show P. (P.) neubergicus in this area to have been confined to the Vijlen Member (Intervals 0–6, Gulpen Formation). This would correspond to the basal sumensis Zone to the lower cimbrica Zone, or tegulatus/junior Zone, depending on placement of the Lower/Upper Maastrichtian boundary. Material available has been collected in recent years at the CBR-Lixhe (Liège, Belgium) and ENCI-Maastricht bv (Maastricht) quarries as well as from outcrop 62D-26 at Vijlenerbosch (Vijlen, the Netherlands). Records of P. (P.) neubergicus, the proposed index for the base of the Maastrichtian Stage, from elsewhere in Europe (northern Spain, SW France, Austria, Denmark, Bulgaria), suggest it to have been fairly long-ranging and show local first occurrences to have been diachronous.