Turonian

The Turonian is a division of the geologic timescale that marks the second age of the Late Cretaceous Epoch. It follows the Cenomanian and precedes the Coniacian. In numerical terms, the Turonian spans roughly 93.9 to 89.8 million years ago.

Geologically, the Turonian was a time of high global temperatures and elevated sea levels, resulting in widespread shallow seas that promoted extensive marine deposition. This warm, marine-dominated world is reflected in thick carbonate sequences and widespread sedimentation in many regions, including Europe and North America. The Cenomanian–Turonian boundary is associated with major changes in the global carbon cycle, widely correlated with the Oceanic Anoxic Event 2, an interval of pronounced oceanic anoxia and organic-rich sediment deposition.

The fossil record of the Turonian documents continued diversification of marine groups such as ammonites and inoceramid bivalves, along with the prominence of marine reptiles including mosasaurs in some seas. On land, flowering plants (angiosperms) continued to diversify, and dinosaurs remained common, with hadrosaurs and other herbivorous forms feeding in the abundant plant-rich environments.

In stratigraphy, the Turonian is recognized as an official stage of the Late Cretaceous in the International Commission on Stratigraphy framework. Its boundaries are defined by distinct changes in fossil assemblages and magnetostratigraphic markers in well-studied sections around the world.