Ammonite faunas and the 'standard zones' of the Cenomanian to Maastrichtian Stages in their type areas, with some proposals for the definition of the stage boundaries by ammonites.

Abstract

The 'standard zones' of the Cenomanian to Maastrichtian Stages as applied to the western European region are critically evaluated, and their development within the type areas of these stages is reviewed. Proposals for defining the bases of the Upper Cretaceous stages worldwide using ammonites are: Cenomanian: appearance of Hypoturrilites Dubourdieu, 1953 or Neostlingoceras Klinger & Kennedy, 1978; Turonian: appearance of Pseudaspidoceras flexuosum Powell, 1963; Coniacian: appearance of Forresteria (Harleites) petrocoriensis (Coquand, 1859); Santonian: appearance of Texanites species; Cam­panian: appearance of either Placenticeras bidorsatum (Roemer, 1841), Submortoniceras Spath, 1921, or on the basis of evolutionary changes within the Scaphites hippocrepis (De Kay, 1827) lineage; Maastrich­tian: appearance of Pachydiscus neubergicus (Von Hauer, 1858).