Aquitanian (stage) in the context of "Annum"

The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between 27.3 and 23.04 Ma. The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage of the Miocene).

The Hemingfordian on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 20,600,000 to 16,300,000 years BP. It is usually considered to overlap the latest Aquitanian and Burdigalian of the Early Miocene. The Hemingfordian is preceded by the Arikareean and followed by the Barstovian NALMA stages.

The Hemingfordian can be further divided into the substages of:

The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.45 Ma and 15.98 Ma (million years ago). Preceded by the Aquitanian, the Burdigalian was the first and longest warming period of the Miocene and is succeeded by the Langhian.

The Agenian age is a period of geologic time (23.8–20 Ma) within the Miocene used more specifically with European Land Mammal Ages. It follows the Orleanian age and overlaps the Aquitanian and Burdigalian ages.