Permian

The Permian (/ˈpɜːr.mi.ən/ PUR-mee-ən)[4] is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia.[5][6][7][8][9]

Permian
298.9 ± 0.15 – 251.902 ± 0.024 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitPeriod
Stratigraphic unitSystem
Time span formalityFormal
Lower boundary definitionFAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline.
Lower boundary GSSPAidaralash, Ural Mountains, Kazakhstan
50.2458°N 57.8914°E / 50.2458; 57.8914
GSSP ratified1996[2]
Upper boundary definitionFAD of the Conodont Hindeodus parvus.
Upper boundary GSSPMeishan, Zhejiang, China
31.0798°N 119.7058°E / 31.0798; 119.7058
GSSP ratified2001[3]

The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the sauropsids (reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior.[10] Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors.

Various authors recognise at least three,[11] and possibly four[12] extinction events in the Permian. The end of the Early Permian (Cisuralian) saw a major faunal turnover, with most lineages of primitive "pelycosaur" synapsids becoming extinct, being replaced by more advanced therapsids. The end of the Capitanian Stage of the Permian was marked by the major Capitanian mass extinction event,[13] associated with the eruption of the Emeishan Traps. The Permian (along with the Paleozoic) ended with the Permian–Triassic extinction event, the largest mass extinction in Earth's history (which is the last of the three or four crises that occurred in the Permian), in which nearly 81% of marine species and 70% of terrestrial species died out, associated with the eruption of the Siberian Traps. It would take well into the Triassic for life to recover from this catastrophe;[14] on land, ecosystems took 30 million years to recover.[15]


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