2004: A Geologic Time Scale 2004, Cambridge University Press. ; 1842: Paléontologie française: Terrains crétacés, vol. ii. External links GeoWhen Database - Aptian Mid-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic charts of the Lower Cretaceous: and , at the website of Norges Network of offshore records of geology and stratigraphy 05 Geological ages Cretaceous geochronology