The Permian is a geological period which started about 299 million years ago (mya), and ended about 252 mya. It is the last period of the Paleozoic era, and ended in the largest mass extinction known to science.
Data[change | edit source]
- 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 minus 20 m in the late Permian.
Climate[change | edit source]
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.
Life[change | edit source]
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.
Insects[change | edit source]
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.
Pangaea[change | edit source]
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.
References[change | edit source]
- Haq B.U.; Schutter, SR (2008). "A chronology of Paleozoic sea-Level changes". Science 322 (5898): 64–68. doi:10.1126/science.1161648. PMID 18832639.
- Levin, Harold L. 2005. The Earth through time. 8th ed, Wiley, N.Y. Chapter 4: The fossil record.
- or class, depending on how they are classified.
- Wooton R.J. 1990. Major insect radiations. In P.D. Taylor & G.P. Larwood eds. Major evolutionary radiations. Oxford.
- Zimmerman EC (1948) Insects of Hawaii. vol II, Univ. Hawaii Press
- Grzimek HC Bernhard 1975. Grzimek's Animal Life Encyclopedia Vol 22 Insects. Van Nostrand Reinhold Co. NY.
- Riek EF Kukalova-Peck J 1984. A new interpretation of dragonfly wing venation based on early Upper Carboniferous fossils from Argentina (Insecta: Odonatoida and basic character states in Pterygote wings.) Can. J. Zool. 62; 1150-1160.
- Erwin D.H. 1993. The great Palaeozoic crisis: life & death in the Permian. Columbia, N.Y.
|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.|