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The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series.See for a detailed geologic timescale Gradstein et al. (2004) An age is a unit of geochronology; it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding age. Both age and stage bear the same name.
As a unit of geologic time measure, the Cenomanian Age spans the time between 100.5 and 93.9 million years ago (Mya). In the geologic timescale, it is preceded by the Albian and is followed by the Turonian. The Upper Cenomanian starts around at 95 Mya.
The Cenomanian is coeval with the Woodbinian of the regional timescale of the Gulf of Mexico and the early part of the Eaglefordian of the regional timescale of the East Coast of the United States.
At the end of the Cenomanian, an anoxic event took place, called the Cenomanian-Turonian boundary event or the "Bonarelli event", that is associated with a minor extinction event for marine species.
Cenomanithrips, an extinct thrips of the Stenurothripidae family, was named after the Cenomanian, the age of the Myanmar amber in which it was discovered.
The top of the Cenomanian (the base of the Turonian) is at the first appearance of ammonite species Watinoceras.
Important for the Cenomanian are the ammonites Calycoceras, Acanthoceras rhotomagense, and Mantelliceras.
The Early Cenomanian was extremely hot, with mid-latitude sea surface temperatures (SSTs) estimated at >31°C and water temperatures in the upper bathyal depths estimated at >17 °C. During the Cenomanian, Labrador's mean annual temperature (MAT) was around 15.1 ± 2.1°C, one of the coldest in North America at this time. Egypt was warm and humid, though occasionally saw intervals of relatively dry conditions.
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