TheCisuralian, also known as theEarly Permian, is the firstseries/epoch of thePermian. The Cisuralian was preceded by thePennsylvanian and followed by theGuadalupian. The Cisuralian Epoch is named after the western slopes of theUral Mountains in Russia andKazakhstan and dates between 298.9 ± 0.15 – 274.4 ± 0.4Ma.[4]
In the regional stratigraphy of southwestern North America, the Cisuralian encompasses two series: theWolfcampian (Asselian to mid-Artinskian) andLeonardian (mid-Artinskian to Kungurian).[5][6][7]
The series saw the appearance ofbeetles andflies and was a relatively stable warming period of about 21 million years.
The Cisuralian is the first series or epoch of the Permian.[8] The Cisuralian was preceded by the last Pennsylvanian epoch (Gzhelian) and is followed by the PermianGuadalupian Epoch.
The name "Cisuralian" was proposed in 1982,[9] and approved by the International Subcommission on Permian Stratigraphy in 1996.[10]The Cisuralian Epoch is named after the western slopes of the Ural Mountains in Russia and Kazakhstan.[11][12][13]
Limestones on the edge ofRussian Platform and make up theIshimbay oil fields. These oil fields were vital to the Soviet Union during WW2 when the Germans controlled the oil fields to the west.[11]
The International Chronostratigraphic Chart (v2018/07)[8] provides a numerical age of 298.9 ± 0.15 – 272.3 ± 0.5 Ma.[14]
The base of the Cisuralian series and the Permiansystem is defined as the place in the stratigraphic record where fossils of the conodontStreptognathodus isolatus first appear. The global reference profile for the base (theGSSP or golden spike) is located in the valley of the Aidaralash River, nearAqtöbe in the Ural Mountains of Kazakhstan.[15]
Gondwana collided withLaurussia and created theAlleghenian orogeny in present-day North America.[11] In northwestern Europe, theHercynian orogeny continued.[11] This created the large supercontinent,Pangea, by the middle of the early Permian, which was to have an impact on the climate.[11]
At the start of the Permian, theLate Palaeozoic Ice Age, which began in theCarboniferous, was at its peak.Glaciers receded over the course of the late Cisuralian as the Earth's climate gradually warmed,[16] particularly during the Artinskian Warming Event,[17] drying the continent's interiors.[18][19][20] The pan-tropical belt of Pangaea experienced particularly significant aridification during this epoch.[21][22][23]
The swampy fringes were mostly ferns, seed ferns, andlycophytes. The series saw the appearance of beetles and flies.[11]
The coal swamps from theCarboniferous declined[24] but the herbivores,DiadectesandEdaphosaurus persisted until the end of this series, approximately.[25][26][27][12] The dry interior had small insectivores.Caseids and prototherapsidTetraceratops made their appearance.[12] The marine life was probably more diverse than modern times as the climate warmed.[11] Unusual sharks such asHelicoprion continued in this series.
^International Commission on Stratigraphy."GSSPs". Retrieved10 July 2018.
^Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. and Snyder, W.S.;1998:Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System, Episodes21(1): pp 11–18.
^Sahney, Sarda; Benton, Michael J.; Falcon-Lang, Howard J. (December 2010). "Rainforest collapse triggered Carboniferous tetrapod diversification in Euramerica".Geology.38 (12):1079–1082.Bibcode:2010Geo....38.1079S.doi:10.1130/g31182.1.ISSN1943-2682.
^Huttenlocker, A. K., and E. Rega. 2012. The Paleobiology and Bone Microstructure of Pelycosaurian-grade Synapsids. Pp. 90–119 in A. Chinsamy (ed.) Forerunners of Mammals: Radiation, Histology, Biology. Indiana University Press.
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