Cretaceous Period

Jurassic Period - Cretaceous Period - Paleogene Period

The Cretaceous Period is the third, and final, period of the Mesozoic Era, and the ninth of the Phanerozoic Eon. The Permian tentatively begins with the base of M18r chron and ends with the Cretaceous-Paleogene extinction, formerly known as the Cretaceous-Tertiary extinction, that was most famous for eliminating the non-avian dinosaurs.

The formation of modern continents went into full-swing during the period, as the Jurassic remnants of Pangaea: Gonwana and Laurasia; further broke apart throughout the period.

Besides the dinosaurs, the pterosaurs and most of the giant marine reptiles including the ichthyosaurs and plesiosaurs went extinct during or at the end of this period. These megafauna would be replaced by mammals and, for a brief period of time, terror birds as the dominant species on Earth. During the Cretaceous, the modern continents began to form. Precipitation increased in the Cretaceous, with more snowfall in the polar regions and rainfall in the equatorial regions.

Mosasaurs, the largest of which was Tylosaurus, evolved during the late Cretaceous, only to go extinct at the end of the period. Sharks, rays, and teleost fish became more abundant throughout this period, and would survive the Cretaceous-Paleogene extinction and survive to the modern day. Insects would diversify in this period, while mammals remained small in size and did not play a major role in the Cretaceous biosphere.

The Cretaceous is subdivided into two epochs, the Early Cretaceous and the Late Cretaceous.

Cretaceous Timescale:

Cretaceous Period - 145-66 MYA

-Early Cretaceous Epoch - 145-100.5 MYA

--Berriasian Age - 145-139.4 MYA

--Valanginian Age - 139.4-134.7 MYA

--Hauterivian Age - 134.7-130.8 MYA

--Barremian Age - 130.8-126.3 MYA

--Aptian Age - 126.3-113.14 MYA

--Albian Age - 113.14-100.5 MYA

-Late Cretaceous Epoch - 100.5-66 MYA

--Cenomanian Age - 100.5-93.9 MYA

--Turonian Age - 93.9-89.75 MYA

--Coniacian Age - 89.75-86.49 MYA

--Santonian Age - 86.49-84.19 MYA

--Campanian Age - 84.19-72.1 MYA

--Maastrichtian Age - 72.1-66 MYA