The Gzhelian Age is the last of four ages in the Pennsylvanian Epoch of the Carboniferous period. It lasted from approximately 303.9±0.9 to 299.0±0.8 million years ago. It was preceded by the Kasimovian age and followed by the Asselian age of the Cisuralian epoch. This age is named after the village of Gzhel in Russia. The Evolutionary radiation of reptiles during the Gzhelian Age suggests that the Earth's climate was possibly becoming drier during that time.