Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch (or, in chronostratigraphy: the fifth of six stages in the Upper Cretaceous series). The Campanian spans the time from 83.6 ± 0.7 Ma to 72.1 ± 0.6 Ma (million years ago). It is preceded by the Santonian and it is followed by the Maastrichtian.
Campanian
The top of the Campanian is defined as the place in the stratigraphic column where the ammonite "Pachydiscus neubergicus" first appears.