From Wikipedia, the free encyclopedia
North American faunal stage
The Arikareean North American Stage on the
geologic timescale is the North American
faunal stage according to the
North American Land Mammal Ages chronology (NALMA), typically set from 30,600,000 to 20,800,000 years
BP, a period of
9.8 million years.
[1] It is usually considered to overlap the
Oligocene and
Miocene epochs. The Arikareean is preceded by the
Whitneyan and followed by the
Hemingfordian NALMA stages.
The Arikareean can be further divided into the substages of:
- late Late Arikareean: Lower boundary source, base of
Geringian (approximate)
[2]
- early Late Arikareean: base of Geringian (approximate). Upper boundary source: base of Hemingfordian (approximate).
- late Early Arikareean: Lower boundary source of base of Geringian (approximate). Upper boundary source of base of Hemingfordian (approximate).
- early Early Arikareean (shares lower boundary): Upper boundary source of base of Hemingfordian (approximate).
References