Britain experienced a warm climate with lagoonal, lake and fluvial environments in the Early Cretaceous. Rocks of this age contain dinosaur remains. Higher sea levels led to chalk deposition in the Late Cretaceous. Many groups of animals became extinct at the end of the Cretaceous including ammonites and dinosaurs.
*Based on The Geologic Time Scale 2012 by F M Gradstein, J G Ogg, M Schmitz and G Ogg (2012), with additions.