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The geological timescale Appendix 3

Phanerozoic Eon
(544 Ma to Present)
The period of time between the end of the Precambrian Eon and today. The Phanerozoic Eon begins with the start of the Cambrian
Period, 544 Ma. The period encompasses the period of abundant, complex life on the Earth.

Era Period or System Epoch or Series
Cenozoic (65 Ma to Present) Quaternary (1.8 Ma to Present) Holocene (8000 years to Present)
Pleistocene (1.8 million to 8000 years)
Tertiary (65–1.8 Ma) Pliocene (5.3–1.8 Ma)
Miocene (23.8–5.3 Ma)
Oligocene (33.7–23.8 Ma)
Eocene (55.5–33.7 Ma)
Palaeocene (65–55.5 Ma)
Mesozoic (248–65 Ma) Cretaceous (145–65 Ma)
Jurassic (213–145 Ma)
Triassic (248–213 Ma)
Palaeozoic (544–248 Ma) Permian (286–248 Ma)
Carboniferous Pennsylvanian*
(360–286 Ma) (325–286 Ma)
Mississippian*
(360–325 Ma)
Devonian (410–360 Ma)
Silurian (440–410 Ma)
Ordovician (505–440 Ma)
Cambrian (544–505 Ma)

Precambrian Eon
(Beginning of the Earth to 544 Ma)
All geological time before the beginning of the Palaeozoic Era. This includes about 90% of all geological time and spans the time from
the beginning of the Earth, about 4500 Ma, to 544 Ma. The Precambrian Eon is usually divided into the Archaen (pre-2500 Ma) and
the Proterozoic (the remainder), both being commonly called eons.
Source: Topinka (2001) http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html
Ma, million years before present.
* North American usage.