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Cretaceous period stages
Timeline of stages in the Cretaceous period
The Cretaceous is the last period of the Mesozoic Era, dating from 144 - 65 mya. It follows the Jurassic, and precedes the Paleocene. The Early Cretaceous I includes the Berriasian, Valanginian, Hauterivian, and Barremian Stages. The Early Cretaceous II covers the Aptian and Albian Stages (144-99 mya). The Late Cretaceous is made up of the Cenomanian, Turonian, Coniacian, Santonian, Campanian, and Maastrichtian Stages (99-65 mya). The symbol for the Cretaceous period on geological maps is K.
The Cretaceous period saw the continued development of both large land reptiles called dinosaurs, and a proliferation of marine reptiles including Mosasaurs and Pleisiosaurs.
The end of the Cretaceous period is marked by a major extinction event called the K/T (Cretacous/Tertiary) extinction. All extant dinosaurs and large marine reptiles became extinct. Starting in the Paleocene period, there occurred a signficiant radiation of mammal types, many of whom evolved from small nocturnal insectivores into large predators, as well as abundant large grazing herd animals.
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