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Permian

The Permian is a geologic period that extends from about 280 to 251 million years before the present. As with most older geologic periods, the rock beds[?] that define the start and end are well identified, but the exact date of the start of the period is uncertain by a few million years. The end of the period is marked by a major extinction event that is more tightly dated. The Permian is named for extensive exposures in the region around the city of Perm[?] in Russia. The Permian follows the Carboniferous (Pennsylvanian in North America) and is followed by the Triassic. Permian exposures consist largely of continental redbeds and shallow water marine exposures.

The Permian is usually broken into Lower and Upper subdivisions. The faunal stages from youngest to oldest are:

  1. Changxingian/Lopingian/Djulfian/Ochoan/Dewey Lake (Zechstein)
  2. Wujiapingian/Lopingian/Dorashamian/Ochoan/Longtanian/Rustler/Salado/Castile (Zechstein)
  3. Capitanian/Guadelupian/Kazanian (Zechstein)
  4. Wordian/Guadelupian/Kazanian (Zechstein)
  5. Roadian/Ufimian/Guadelupian (Zechstein)
  6. Kungurian/Irenian/Filippovian/Leonard (Rotliegendes)
  7. Artinskian/Baigendzinian/Aktastinian (Rotliegendes)
  8. Sakmarian/Sterlitamakian/Tastubian/Leonard/Wolfcamp (Rotliegendes)
  9. Asselian/Krumaian/Uskalikian/Surenian/Wolfcamp (Rotliegendes)

Sea levels in the Permian were low and near shore environments were limited by the collection of almost all major landmasses[?] into a single continent -- Pangea. One continent - even a large continent - has less shoreline than six to eight smaller ones. The Permian ended with the most extensive extinction event recorded in paleontology. 90% to 95% of marine species became extinct. There is very modest evidence that the extinction was caused by weather changes[?] due to impact by a large meteorite. Land life in the Permian included diverse plants, large amphibians and large reptiles including the ancestors of the dinosaurs. The first modern trees - conifers - appeared in the Permian. Permian marine deposits are rich in mollusks, echinoderms, and brachiopods. The last trilobites died out before the end of the Permian.

During the Permian, all the Earth's major land masses except portions of East Asia were collected into a single landmass known as Pangea. Pangea straddled the equator. Deserts seem to have been widespread in Pangea.

The Permian Basin in the U.S. state of Texas is so named because it has one of the thickest deposits of Permian rocks in the world.



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