Cenomanianage

The Cenomanian age is the first age of the Late Cretaceous epoch, spanning roughly 100.5 to 93.9 million years ago. In the modern geologic timescale it follows the Albian and precedes the Turonian, and regional charts sometimes divide it into lower, middle, and upper intervals.

During the Cenomanian, global climate was warm and sea levels were high, producing widespread shallow seas that covered many landmasses. This transgression supported expansive carbonate platforms and diverse marine habitats in many regions, while continental climates remained tropical in low latitudes. The combination of warmth and high seas fostered significant evolutionary activity among marine invertebrates and early flowering plants on land.

Biotic developments in the Cenomanian included continued diversification of marine organisms such as ammonites and belemnites, as well as reef-building organisms in suitable environments. On land, gymnosperms and the early angiosperms (flowering plants) diversified in various ecological settings, accompanying diversification of other vertebrate groups in contemporary ecosystems.

Stratigraphically, the Cenomanian provides a key interval for correlating rocks worldwide. The boundary at the end of the Cenomanian marks the start of the Turonian and is associated with a major global perturbation in the carbon cycle known as Oceanic Anoxic Event 2. This event led to significant deposition of organic-rich sediments in several deep basins and is linked to notable changes in marine faunas.