What is "clarendonian"

The Clarendonian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 13,600,000 to 10,300,000 years BP, a period of .

It is usually considered to overlap the Serravallian of the Middle Miocene epoch and Tortonian epoch of the Late Miocene. The Clarendonian is preceded by the Barstovian and followed by the Hemphillian NALMA stages.