Wikipedia
Serravallian
The Serravallian is in the geologic timescale an age or a stage in the middle Miocene epoch/ series, that spans the time between 13.65 ± 0.05 Ma and 11.608 ± 0.005 Ma (million years ago). The Serravallian follows the Langhian and is followed by the Tortonian.
It overlaps with the middle of the Astaracian European Land Mammal Mega Zone, the upper Barstovian and lower Clarendonian North American Land Mammal Ages and the Laventan and lower Mayoan South American Land Mammal Ages. It is also coeval with the Sarmatian and upper Badenian stages of the Paratethys time scale of Central and eastern Europe.