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Geologic timescale

(not shown to scale)

Years Ago^3,6 Epoch Period/Age^4,5 Era Eon Major Events

Present day Holocene Quaternary Cenozoic Phanerozoic

10,000 Pleistocene Extinction of many large mammals. Evolution of fully modern humans

1.6 million Pliocene Tertiary Neogene

5 million Miocene

23 million Oligocene Paleogene

38 million Eocene

55 million Paleocene

64.3 million^* Cretaceous Mesozoic Dinosaurs reach peak, become extinct. Primitive placental mammals

146 million Jurassic Marsupial mammals, first birds, first flowering plants[?]

208 million Triassic First dinosaurs, Egg-laying mammals

251.1 million^* Permian Paleozoic Permian extinction event- 95% of life on Earth becomes extinct

286 million Carboniferous¹ Pennsylvanian Abundant insects, first reptiles, coal forests

325 million Mississippian Large primitive trees

360 million Devonian First amphibians, clubmosses and horsetails appear, progymnosperms[?] (first seed bearing plants) appear

408.5 million^* Silurian First land plant fossils

443.5 million^* Ordovician Invertebrates dominant

490 million^* Cambrian Major diversification of life in the Cambrian explosion

545 million^* Neoproterozoic² Proterozoic Precambrian First multi-celled animals

900 million Mesoproterozoic[?]

1,600 million Paleoproterozoic First Complex single-celled life

2,500 million Archaean Simple single-celled life

3,800 million Hadean Formation of Earth

1) In North America, the Carboniferous is subdivided into Mississippian and Pennsylvanian Periods

2) Discoveries in the past quarter century have substantially changed the view of geologic and paleontologic events immediately prior to the Cambrian. The nomenclature has not stabilized. The term Neoproterozoic is used here, but other writers might equally well have used one or more of the terms 'Ediacarian', 'Vendian', 'Varangian', 'Precambrian', 'Protocambrian', 'Eocambrian', or might have extended the Cambrian further back in time. All of these terms are usually treated as a subset of the Proterozoic rather than a period between the Paleozoic and the Proterozoic.

3) Dates are slightly uncertain with differences of a few percent between various sources being common. This is largely due to uncertainties in radiometric dating and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where we would most like to have them. Dates with an * are radiometrically determined based on internationally agreed to GSSPs. All dates given are for the end of the epoch in question.

4) Paleontologists often refer to faunal stages rather than geologic Periods. The Stage Nomenclature is quite complex. See http://flatpebble.nceas.ucsb.edu/public/harland.html for an excellent time ordered list of faunal stages. Also see the article on GSSPs.

5) In common usage the Tertiary-Quaternary and Paleogene-Neogene-Quaternary Periods are treated as equivalents to the Mesozoic and Paleozoic Periods. The term 'Period|Age' (e.g. 'Neogene Period|Age') is sometimes used instead of 'Period'.

6) The time shown in the "Years Ago" column is that of the end of the Epoch in the "Epoch" column.

See also:

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