23.1 - 18.5 Ma

The definition of this interval in the timescale North American Mammal Subages/Zones is taken from the following source:

• J. Alroy. 2000. New methods for quantifying macroevolutionary patterns and processes. Paleobiology 26(4):707-733 view

The bottom age has been interpolated based on the differences between the ages for international timescale boundaries quoted in the source and the currently accepted ages for those boundaries.

There are intervals in 11 timescales which overlap this one. show

• International Chronostratigraphic Timescale: Aquitanian age, Burdigalian age, Oligocene epoch, Chattian age, Miocene epoch
• Cenozoic Subepochs: Early Miocene subepoch, Late Oligocene subepoch
• European Faunal Units: Agenian subage, Orleanian subage
• European Faunal Zones: MN 1 zone, MN 2 zone, MN 3 zone
• Mammal Paleogene Zones: MP 25 zone, MP 27 zone, MP 26 zone, MP 30 zone, MP 28 zone, MP 29 zone
• Neogene Mammal Ages of China: Xiejiaan age
• Paleogene Mammal Ages of Asia: Hsandagolian age, Tabenbulakian age
• North American Land Mammal Ages: Arikareean age
• North American Mammal Subages/Zones: late Early Arikareean subage, early Early Arikareean subage, late Late Arikareean subage, early Late Arikareean subage
• South American Land Mammal Ages: Colhuehuapian age, Deseadan age
• Cretaceous-Cenozoic of New Zealand: Pareora epoch, Landon epoch, Waitakian age, Otaian age, Altonian age

This interval is used in the definition of 150 collections

A total of 2403 collections with 19810 occurrences lie within this time span