The Permian is a geological period which started about 299 million years ago, and ended about 252 million years ago. It is the last period of the Paleozoic era, and ended in the largest mass extinction known to science.
- Oxygen content of atmosphere: 23% (115% of modern level).
- Average CO2 content: 900 ppm (3 times pre-industrial level)
- Average surface temperature: ~16oC (2oC above modern level)
- Sea level: 60 metres above present day level; plummeting during the middle Permian to a constant -20 m in the late Permian.
The climate in the Permian was quite varied. At the start of the Permian, the Earth was still at the grip of an Ice age from the Carboniferous. Glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continent's interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles.
During the Permian tetrapod life, (amphibians, Sauropsids and Synapsids) which evolved in the Carboniferous, became widespread and diverse. The first modern trees (conifers, ginkgos and cycads) appeared in the Permian.
The Permian was also a period of adaptive radiation in insects. Beetles (Coleoptera) appeared; so did flies (Diptera). 22 out of a total of 36 known orders of insects are known from the Permian. Some became extinct in the end-Permian event, but more radiation followed in the Mesozoic. Insects were probably, by the end of the Permian, the largest phylum in terms of number of species.
All the major land masses were collected together in the super-continent Pangaea. At the end of the period, the greatest flood basalt lava flows in the Phanerozoic raised world temperatures, and damaged the environment. These formed the extensive Siberian traps. The causes of the Permian/Triassic extinction event are not yet agreed between scientists. Trilobites, once a dominant life-form in the ocean, became extinct, together with 90% of all marine species.
- International Stratigraphic Chart. 
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- or class, depending on how they are classified.
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|Precambrian (4.567 gya – 541 mya)|
|In the left column are Eons, bold are Eras, not bold are Periods. gya = billion years ago, mya = million years ago|
|Hadean (4.567 gya – 4 gya)|
|Archaean (4 gya – 2.5 gya)||Eoarchaean (4 gya – 3.6 gya)|
|Proterozoic (4 gya – 2.5 gya)||Palaeoproterozoic (2.5 gya – 1.6 gya) Siderian (2.5 gya – 2.3 gya) Rhyacian (2.3 gya – 2.05 gya) Orosirian (2.05 gya – 1.8 gya) Statherian (1.8 gya – 1.6 gya)|
|Phanerozoic (541 mya – today)|
|In the left column are Eras, bold are Periods, not bold or italics are Epochs, Italics are stages. kya = thousand years ago, mya = million years ago|
|Palaeozoic (541 mya – 252.17 mya)||Cambrian (541 mya – 485.4 mya)
Permian (298.9 mya – 252.17 mya)
|Mesozoic (252.17 mya – 66.0 mya)||Triassic (252.17 mya – 201.3 mya) Lower Triassic (252.17 mya – 247.2 mya) Middle Triassic (247.2 mya – 237 mya) Upper Triassic (237 mya – 201.3 mya)|
|Cainozoic (66.0 mya – today)||Palaeogene (66.0 mya – 23.03 mya) Palaeocene (66.0 mya – 56 mya) Eocene (56 mya - 33.9 mya) Oligocene (33.9 mya – 23.03 mya)|
|Source||International Chronostratigraphic Chart 2013. International Commission on Stratigraphy, retrieved 8 April 2013. Divisions of geologic time – major chronostratigraphic and geochronologic units USGS, retrieved 8 April 2013.|