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: Miocene epoch, Chattian age, Aquitanian age, Oligocene epoch, Burdigalian age
• 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 27 zone, MP 26 zone, MP 29 zone, MP 25 zone, MP 28 zone, MP 30 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: early Early Arikareean subage, early Late Arikareean subage, late Late Arikareean subage, late Early Arikareean subage
• South American Land Mammal Ages: Deseadan age, Colhuehuapian age
• Cretaceous-Cenozoic of New Zealand: Altonian age, Pareora epoch, Waitakian age, Landon epoch, Otaian age

This interval is used in the definition of 151 collections

A total of 2258 collections with 18354 occurrences lie within this time span