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The Permian ( ) is a
geologic period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of divisions into which geologists have split the Earth' ...
and stratigraphic system which spans 47 million years from the end of the
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, Mya. The name ''Carboniferous'' means "coal-b ...
period million years ago (Mya), to the beginning of the
Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of ...
period 251.902 Mya. It is the last period of the
Paleozoic The Paleozoic (or Palaeozoic) Era ( ; from the Greek ''palaiós'' (), "old" and ''zōḗ'' (), "life", meaning "ancient life") is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from ...
era; the following Triassic period belongs to the
Mesozoic The Mesozoic Era ( ) meaning "middle life" is the middle of the three geological eras of the Phanerozoic Eon. It lasted from about . It is also called the Age of Reptiles and the Age of Conifers. The Mesozoic was preceded by the Paleozoic ("ancie ...
era. The concept of the Permian was introduced in 1841 by geologist Sir
Roderick Murchison Sir Roderick Impey Murchison, 1st Baronet, (22 February 1792 – 22 October 1871) was a British geologist who first described and investigated the Silurian system. Early life and work Murchison was born at Tarradale House, Muir of Ord, Ross-s ...
, who named it after the region of Perm in
Russia Russia (russian: link=no, Россия, , ), or the Russian Federation, is a country spanning Eastern Europe and Northern Asia. It is the largest country in the world, covering and encompassing more than one-eighth of the Earth's inhabited l ...
. The Permian witnessed the diversification of the two groups of
amniote Amniotes (from Greek ἀμνίον ''amnion'', "membrane surrounding the fetus", earlier "bowl in which the blood of sacrificed animals was caught", from ἀμνός ''amnos'', "lamb") are a clade of tetrapod vertebrates comprising reptiles (c ...
s, the
synapsids Synapsids are a group of animals that includes mammals and every animal more closely related to mammals than to the other members of the amniote clade, such as reptiles and birds. They are easily separated from other amniotes by having a temporal ...
and the
sauropsids Sauropsida ("lizard faces") is a clade of amniotes, broadly equivalent to the class Reptilia. Sauropsida is the sister taxon to Synapsida, the clade of amniotes which includes mammals as its only modern representatives. Although early synapsids hav ...
(
reptiles Reptiles are tetrapod animals in the class or clade Reptilia . As a class in Linnean taxonomy, Reptilia refers to a paraphyletic grouping comprising all amniotes (vertebrates which encase their embryos in a series of protective sacs) except syn ...
). The world at the time was dominated by the supercontinent
Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and began to break apart about 175 million years ago. In ...

Pangaea
, which had formed due to the collision of
Euramerica Laurasia (), a portmanteau for Laurentia and Asia, was the more northern of two large landmasses (the other being Gondwana) that formed part of the Pangaea supercontinent from around (Mya). It separated from Gondwana (beginning in the late Tria ...
and
Gondwana Gondwana () or Gondwanaland was a supercontinent that existed from the Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic (about 180 million years ago), with the opening of the Drake Passage, separating South ...
during the Carboniferous. The continent of
Angara The Angara (Buryat and mn, Ангар, ''Angar'',  "Cleft"; russian: Ангара́, ''Angará'') is a major river in Siberia, which traces a course through Russia's Irkutsk Oblast and Krasnoyarsk Krai. It drains out of Lake Baikal and is the ...
lay to the northeast of Pangaea. Pangaea was surrounded by the superocean
Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea. During the Paleozoic–Mesozoic transition 250  it occupied almost 70% of ...
. The
Carboniferous rainforest collapse The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. It altered the vast coal forests that covered the equatorial region of Euramerica (Europe and America). ...
left behind vast regions of
desert upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab Emirates A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for ...
within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The end of the
Capitanian In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian epoch or series. The Capitanian lasted between and million years ago. It was preceded by the ...
stage of the Permian was marked by the major Capitanian mass extinction event, associated with the eruption of the
Emeishan Traps The Emeishan Traps constitute a flood basalt volcanic province, or large igneous province, in south-western China, centred in Sichuan province. It is sometimes referred to as the Permian Emeishan Large Igneous Province or Emeishan Flood Basalts. Lik ...
. The Permian (along with the Paleozoic) ended with the
Permian–Triassic extinction event The Permian–Triassic extinction event, also known as the P–Tr extinction, the P–T extinction, the End-Permian Extinction, and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well a ...
, the largest mass extinction in Earth's history, in which nearly 81% of marine species and 70% of terrestrial species died out, associated with the eruption of the
Siberian Traps The Siberian Traps (russian: Сибирские траппы, ) is a large region of volcanic rock, known as a large igneous province, in Siberia, Russia. The massive eruptive event that formed the traps is one of the largest known volcanic even ...
in Angara. It would take well into the Triassic for life to recover from this catastrophe; on land, ecosystems took 30 million years to recover.


Etymology

The term "Permian" was introduced into
geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over t ...
in 1841 by Sir Roderick Impey Murchison, president of the
Geological Society of London The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows. Fell ...

Geological Society of London
, after extensive Russian explorations undertaken with
Édouard de Verneuil Philippe Édouard Poulletier de Verneuil (13 February 180529 May 1873) was a French paleontologist. Life He was born in Paris and educated in law, but being of independent means he was free to follow his own inclinations, and having attended lectu ...
in the region between the
Volga The Volga (; rus, Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the longest river in Europe. Flowing through Central Russia to Southern Russia and into the Caspian Sea, it has a length of and a catchment area of .Ural Mountains The Ural Mountains (; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈgorɨ; ba, Урал тауҙары, ''Ural tauźarı'') or simply the Urals, are a mountain range that runs approximately from north to south throu ...
. Murchison identified "vast series of beds of marl, schist, limestone, sandstone and conglomerate” that succeeded Carboniferous strata in the region. Murchison named the period after the medieval kingdom of
Permia 275px, Map of Northern Russia, including Permia; by Gerard Mercator (Amsterdam, 1595). Great Perm (russian: Пермь Великая), or simply Perm, Latinised ''Permiae'', was a medieval Komi state in what is now the Perm Krai of the Russian Fed ...
that occupied the same region, which now lies in the
Perm Krai Perm Krai ( rus, Пе́рмский край, r=Permsky kray, p=ˈpʲɛrmskʲɪj ˈkraj) is a federal subject of Russia (a krai) that came into existence on December 1, 2005 as a result of the 2004 referendum on the merger of Perm Oblast and Komi ...
of Russia. Between 1853 and 1867,
Jules Marcou Jules Marcou (April 20, 1824 – April 17, 1898) was a French, Swiss and American geologist. Biography He was born at Salins, in the ''département'' of Jura, in France. He was educated at Besançon and at the Collège Saint Louis, Paris. After c ...
recognised Permian strata in a large area of North America from the
Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system on the North American continent, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minne ...
to the
Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. states ...

Colorado River
and proposed the name "Dyassic", from "Dyas" and "Trias", though Murchison rejected this in 1871.


Geology

The Permian period is divided into three
epochs In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by c ...
, from oldest to youngest, the Cisuralian, Guadalupian, and Lopingian. Geologists divide the rocks of the Permian into a
stratigraphic through Jurassic strata of the Colorado Plateau area of southeastern Utah demonstrate the principles of stratigraphy. Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primari ...
set of smaller rock units called
stages Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Stage ...
, each formed during corresponding time intervals called ages. Stages can be defined globally or regionally. For ''global'' stratigraphic correlation, the
International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigrap ...
(ICS) ratify global stages based on a
Global Boundary Stratotype Section and Point The 'golden spike' marking the Ediacaran GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...
(GSSP) from a single
formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary m ...
(a
stratotypeA stratotype or type section is a geological term that names the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, w ...
) identifying the lower boundary of the stage. The ages of the Permian from youngest to oldest are:Cohen, K.M., Finney, S.C., Gibbard, P.L. & Fan, J.-X. (2013; updated
The ICS International Chronostratigraphic Chart
Episodes 36: 199-204.
Historically, most marine biostratigraphy of the Permian was based on
ammonoids Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid, and cuttlefish) ...
, however ammonoid localities are rare in Permian stratigraphic sections, and species characterise relatively long periods of time. All GSSPs for the Permian are based around the
first appearance datumFirst appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particula ...
of specific species of
conodont Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are extinct agnathan chordates resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils found in isolation and now called conod ...
, an enigmatic group of jawless
chordates A chordate () is an animal of the phylum Chordata (). During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail: these four anatomical features define this phylum. Chorda ...
whos hard teeth like oral elements are key
index fossils Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biolog ...
for most of the Palaeozoic and the Triassic. The Cisuralian Series is named after the strata exposed on the western slopes of the Ural Mountains in Russia and Khazakhstan. The name was proposed by J. B. Waterhouse in 1982 to comprise the Asselian, Sakmarian, and Artinskian stages. The Kungurian was later added to conform to the Russian "Lower Permian".
Albert Auguste Cochon de Lapparent Albert-Auguste de Lapparent Albert Auguste Cochon de Lapparent (30 December 18395 May 1908) was a French geologist. Life He was born at Bourges. After studying at the École polytechnique from 1858 to 1860 he became ''ingénieur au corps des mines ...
in 1900 had proposed the "Uralian Series", but the subsequent inconsistent usage of this term meant that it was later abandoned. The Asselian was named by the Russian stratigrapher V.E. Ruzhenchev in 1954, after the
Assel River Assel () is a village in the commune of Bous, in south-eastern Luxembourg. , the village had a population of 157. Remich (canton) Villages in Luxembourg {{Remich-geo-stub ...
in the southern Ural Mountains. The GSSP for the base of the Asselian is located in the Aidaralash River valley near
Aqtöbe Aktobe ( kz, Ақтөбе, Aqtöbe) is a city on the Ilek River in Kazakhstan. It is the administrative center of Aktobe Region. In 2020, it had a population of 500,757 people. Etymology The name "Aktobe" comes from Kazakh "ақ" (white) and "тө ...
, Kazakhstan, which was ratified in 1996. The beginning of the stage is defined by the first appearance of '' Streptognathodus postfusus.'' The Sakmarian is named in reference to the Sakmara River in the southern Urals, and was coined by Alexander Karpinsky in 1874. The GSSP for the base of the Sakmarian is located at the Usolka section in the southern Urals, which was ratified in 2018. The GSSP is defined by the first appearance of ''Sweetognathus, Sweetognathus binodosus''. The Artinskian was named after the city of Arti, Russia, Arti in Sverdlovsk Oblast, Russia. It was named by Karpinsky in 1874. The Artinskian currently lacks a defined GSSP. The proposed definition for the base of the Artinskian is the first appearance of ''Sweetognathus aff. S. whitei.'' The Kungurian takes its name after Kungur, a city in Perm Krai. The stage was introduced by Alexandr Antonovich Stukenberg in 1890. The Kungurian currently lacks a defined GSSP. Recent proposals have suggested the appearance of Neostreptognathodus, ''Neostreptognathodus pnevi'' as the lower boundary. The Guadalupian Series is named after the Guadalupe Mountains in Texas and New Mexico, where extensive marine sequences of this age are exposed. It was named by George Herbert Girty in 1902.Glenister, B.F., Wardlaw, B.R. et al. 1999
Proposal of Guadalupian and component Roadian, Wordian and Capitanian stages as international standards for the middle Permian series
''Permophiles'', 34, 3–11.
The Roadian was named in 1968 in reference to the Road Canyon Member of the Word Formation in Texas. The GSSP for the base of the Roadian is located 42.7m above the base of the Cutoff Formation in Stratotype Canyon, Guadalupe Mountains, Texas, and was ratified in 2001. The beginning of the stage is defined by the first appearance of Jinogondolella, ''Jinogondolella nankingensis''. The Wordian was named in reference to the Word Formation by Johan August Udden in 1916, Glenister and Furnish in 1961 was the first publication to use it as a chronostratigraphic term as a substage of the Guadalupian stage. The GSSP for the base of the Wordian is located in Guadalupe Pass, Texas, within the sediments of the Getaway Limestone Member of the Cherry Canyon Formation, which was ratified in 2001. The base of the Wordian is defined by the first appearance of the conodont ''Jinogondolella postserrata.'' The Capitanian is named after the Capitan Reef in the Guadalupe Mountains of Texas, named by George Burr Richardson in 1904, and first used in a chronostratigraphic sense by Glenister and Furnish in 1961 as a substage of the Guadalupian stage. The Captianian was ratified as an international stage by the ICS in 2001. The GSSP for the base of the Captianian is located at Nipple Hill in the southeast Guadalupe Mountains of Texas, and was ratified in 2001, the beginning of the stage is defined by the first appearance of ''Jinogondolella postserrata.'' The Lopingian was first intoduced by Amadeus William Grabau in 1923 as the “Loping Series” after Leping, Jiangxi, China. Originally used as a lithostraphic unit, T.K. Huang in 1932 raised the Lopingian to a series, including all Permian deposits in South China that overlie the Maokou Limestone. In 1995, a vote by the Subcommission on Permian Stratigraphy of the ICS adopted the Lopingian as an international standard chronostratigraphic unit.''; 2006
''The Global Stratotype Section and Point (GSSP) for the boundary between the Capitanian and Wuchiapingian Stage (Permian)'',
Episodes 29(4), pp. 253–262
'' The Wuchiapinginan and Changhsingian were first introduced in 1962, by J. Z. Sheng as the "Wuchiaping Formation" and "Changhsing Formation" within the Lopingian series. The GSSP for the base of the Wuchiapingian is located at Penglaitan, Guangxi, China and was ratified in 2004. The boundary is defined by the first appearance of Clarkina, ''Clarkina postbitteri postbitteri'''''' The Changhsingian was originally derived from the Changxing Limestone, a geological unit first named by the Grabau in 1923, ultimately deriving from Changxing County, Zhejiang .The GSSP for the base of the Changhsingian is located 88 cm above the base of the Changxing Limestone in the Meishan D section, Zhejiang, China and was ratified in 2005, the boundary is defined by the first appearance of ''Clarkina wangi.'' The GSSP for the base of the Triassic is located at the base of Bed 27c at the Meishan D section, and was ratified in 2001. The GSSP is defined by the first appearance of the conodont ''Hindeodus, Hindeodus parvus''.


Paleogeography

During the Permian, all the Earth's major landmasses were collected into a single supercontinent known as
Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and began to break apart about 175 million years ago. In ...

Pangaea
, with the Continental fragment, microcontinental terranes of Cathaysia to the east. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean ("
Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea. During the Paleozoic–Mesozoic transition 250  it occupied almost 70% of ...
", the "universal sea"), and the Paleo-Tethys Ocean, a large ocean that existed between Asia and Gondwana. The Cimmeria (continent), Cimmeria continent rifted away from
Gondwana Gondwana () or Gondwanaland was a supercontinent that existed from the Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic (about 180 million years ago), with the opening of the Drake Passage, separating South ...
and drifted north to Laurasia, causing the Paleo-Tethys Ocean to shrink. A new ocean was growing on its southern end, the Tethys Ocean, Neotethys Ocean, an ocean that would dominate much of the
Mesozoic The Mesozoic Era ( ) meaning "middle life" is the middle of the three geological eras of the Phanerozoic Eon. It lasted from about . It is also called the Age of Reptiles and the Age of Conifers. The Mesozoic was preceded by the Paleozoic ("ancie ...
era. The Central Pangean Mountains, which began forming due to the collision of Laurasia and Gondwana during the Carboniferous, would reach their maximum height during the early Permian around 295 million years ago, comparable to the present Himalayas. Large continental landmass interiors experience climates with extreme variations of heat and cold ("continental climate") and monsoon conditions with highly seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a protective cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees (Pinophyta, conifers, ginkgos and cycads) appeared in the Permian. Three general areas are especially noted for their extensive Permian deposits—the
Ural Mountains The Ural Mountains (; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈgorɨ; ba, Урал тауҙары, ''Ural tauźarı'') or simply the Urals, are a mountain range that runs approximately from north to south throu ...
(where Perm itself is located), China, and the southwest of North America, including the Red Beds of Texas and Oklahoma, Texas red beds. The Permian Basin (North America), Permian Basin in the U.S. states of Texas and New Mexico is so named because it has one of the thickest deposits of Permian rocks in the world.


Paleoceanography

Sea levels dropped slightly during the earliest Permian (Asselian) .The sea level was stable at several tens of metres above present during the Early Permian, but there was a sharp drop beginning during the Roadian, culmanating in the lowest sea level of the entire Palaeozoic at around present sea level during the Wuchiapingian, followed by a slight rise during the Changhsingian.


Climate

At the start of the Permian, the Earth was still in the Late Paleozoic icehouse, which began in the latest Devonian. At the beginning of the Pennsylvanian (geology), Pennsylvanian around 323 million years ago, glaciers began to form around the South Pole, which would grow to cover a vast area extending from the southern reaches of the Amazon Basin (sedimentary basin), Amazon basin and covering large areas of southern Africa, as well as most of Australia and Antarctica. Cyclothems indicate that the size of the glaciers were controlled by Milankovitch cycles akin to recent ice ages, with glacial periods and interglacials. The oldest cyclotherms are around 313 million years old while the youngest are around 293 million years old, corresponding to the coldest part of the Late Paleozoic icehouse. Deep ocean temperatures during this time were cold due to the influx of cold bottom waters generated by seasonal melting of the ice cap. By 285 million years ago, temperatures warmed and the South Pole ice cap retreated, though glaciers would remain present in the upland regions of eastern Australia, the Transantarctic Mountains, and the mountainous regions of far northern Siberia until the end of the Permian. The Permian was cool in comparison to most other geologic time periods, with modest Pole to Equator temperature gradients. This was interrupted by the Emeishan Thermal Excursion in the late part of the Capitanian, around 260 million years ago, corresponding to the eruption of the
Emeishan Traps The Emeishan Traps constitute a flood basalt volcanic province, or large igneous province, in south-western China, centred in Sichuan province. It is sometimes referred to as the Permian Emeishan Large Igneous Province or Emeishan Flood Basalts. Lik ...
. The end of the Permian is marked by the much larger temperature excursion at the Permian-Triassic boundary, corresponding to the eruption of the
Siberian Traps The Siberian Traps (russian: Сибирские траппы, ) is a large region of volcanic rock, known as a large igneous province, in Siberia, Russia. The massive eruptive event that formed the traps is one of the largest known volcanic even ...
, which released more than 5 teratonnes of CO2 , more than doubling atmospheric carbon dioxide concentrations.


Life


Marine biota

Permian marine deposits are rich in fossil Mollusca, mollusks, echinoderms, and brachiopods. Brachiopods would reach an apex of diversity during the Permian. Fossilized shells of two kinds of invertebrates are widely used to identify Permian strata and correlate them between sites: Fusulinida, fusulinids, a kind of shelled amoeba-like protist that is one of the foraminiferans, and
ammonoids Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid, and cuttlefish) ...
, shelled cephalopods that are distant relatives of the modern nautilus. By the close of the Permian, trilobites and a host of other marine groups became extinct. Conodonts experienced their lowest diversity of their entire evolutionary history during the Permian.


Terrestrial biota

Terrestrial life in the Permian included diverse plants, Fungus, fungi, arthropods, and various types of List of Permian tetrapods, tetrapods. The period saw a massive desert covering the interior of
Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and began to break apart about 175 million years ago. In ...

Pangaea
. The warm zone spread in the northern hemisphere, where extensive dry desert appeared. The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. A number of older types of plants and animals died out or became marginal elements. The Permian began with the Carboniferous flora still flourishing. About the middle of the Permian a major transition in vegetation began. The swamp-loving Lycopodiophyta, lycopod trees of the Carboniferous, such as ''Lepidodendron'' and ''Sigillaria'', were progressively replaced in the continental interior by the more advanced Pteridospermatophyta, seed ferns and early Pinophyta, conifers as a result of the
Carboniferous rainforest collapse The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. It altered the vast coal forests that covered the equatorial region of Euramerica (Europe and America). ...
. At the close of the Permian, lycopod and Equisetopsida, equisete swamps reminiscent of Carboniferous flora survived only on a series of equatorial islands in the Paleo-Tethys Ocean that later would become South China (continent), South China. The Permian saw the radiation of many important conifer groups, including the ancestors of many present-day families. Rich forests were present in many areas, with a diverse mix of plant groups. The southern continent saw extensive seed fern forests of the ''Glossopteris'' flora. Oxygen levels were probably high there. The Ginkgoopsida, ginkgos and cycads also appeared during this period.


Insects

From the Pennsylvanian (geology), Pennsylvanian subperiod of the
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, Mya. The name ''Carboniferous'' means "coal-b ...
period until well into the Permian, the most successful insects were primitive Blattoptera, relatives of cockroaches. Six fast legs, four well-developed folding wings, fairly good eyes, long, well-developed antennae (olfactory), an omnivorous digestive system, a receptacle for storing sperm, a chitin-based exoskeleton that could support and protect, as well as a form of gizzard and efficient mouth parts, gave it formidable advantages over other herbivorous animals. About 90% of insects at the start of the Permian were cockroach-like insects ("Blattopterans"). Primitive forms of Dragonfly, dragonflies (Odonata) were the dominant aerial predators and probably dominated terrestrial insect predation as well. , and all are effectively semi-aquatic insects (aquatic immature stages, and terrestrial adults), as are all modern odonates. Their prototypes are the oldest winged fossils, dating back to the Devonian, and are different in several respects from the wings of other insects. Fossils suggest they may have possessed many modern attributes even by the late
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, Mya. The name ''Carboniferous'' means "coal-b ...
, and it is possible that they captured small vertebrates, for at least Meganeuropsis, one species had a wing span of . Several other insect groups appeared or flourished during the Permian, including the Coleoptera (beetles), Hemiptera (true bugs) and Orthoptera.


Tetrapods

The terrestrial fossil record of the Permian is patchy and temporally discontinuous. Early Permian records are dominated by equatorial Europe and North America, while those of the Middle and Late Permian are dominated by temperate Karoo Supergroup sediments of South Africa and the Ural region of European Russia. Early Permian terrestrial faunas of North America and Europe were dominated by pelycosaurs including the herbivorous Edaphosauridae, edaphosaurids, and carnivorous Sphenacodontidae, sphenacodontids, Diadectidae, diadectids and amphibians,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. An extinction, dubbed "Olson's Extinction" is thought to have occurred during the Early-Middle Permian transition, with the most notable effect being the decline of amphibian taxa. The Middle Permian faunas of South Africa and Russia are dominated by primitive therapsids, most abundantly by the diverse Dinocephalia. Dinocephalians become extinct at the end of the Middle Permian, during the Capitanian mass extinction event. Late Permian faunas are dominated by advanced therapsids such as the predatory gorgonopsians and herbivorous dicynodonts, alongside large herbivorous pareiasaur Parareptilia, parareptiles. Towards the very end of the Permian the first Archosauriformes, archosauriforms appeared, a group that would give rise to the pseudosuchians, dinosaurs, and pterosaurs in the Triassic, following period. Also appearing at the end of the Permian were the first cynodonts, which would go on to evolve into mammals during the Triassic. Another group of therapsids, the therocephalians (such as ''Lycosuchus''), arose in the Middle Permian. There were no flying vertebrates (though a family of gliding reptiles known as Weigeltisauridae, weigeltisaurs was present in the Late Permian). Synapsids (the group that would later include mammals) thrived and diversified greatly at this time. Permian synapsids included some large members such as ''Dimetrodon''. The special adaptations of synapsids enabled them to flourish in the drier climate of the Permian and they grew to dominate the vertebrates. Permian stem-amniotes consisted of temnospondyli, lepospondyli and Batrachosauria, batrachosaurs. Temnospondyls reached a peak of diversity in the Cisuralian, with a substantial decline during the Guadalupian-Lopingian following Olson's extinction, with the family diversity dropping below Carboniferous levels. Embolomeri, Embolomeres, a group of aquatic crocodile-like Reptiliomorpha, reptilliomorphs that previously had its last records in the Cisuralian, are now known to have persisted into the Lopingian in China. Modern amphibians (Lissamphibia, lissamphibians) are suggested to have originated during Permian, descending from a lineage of Dissorophoidea, dissorophoid temnospondyls. File:EdaphosaurusDB.jpg, ''Edaphosaurus, Edaphosaurus pogonias'' and ''Platyhystrix'' – Early Permian, North America and Europe File:Dimetr eryopsDB.jpg, ''Dimetrodon, Dimetrodon grandis'' and ''Eryops'' – Early Permian, North America File:Ocher fauna DB.jpg, Ocher fauna, ''Estemmenosuchus, Estemmenosuchus uralensis'' and ''Eotitanosuchus'' – Middle Permian, Ural Region File:Titanophoneus 3.jpg, ''Titanophoneus'' and ''Ulemosaurus'' – Ural Region File:Inostrancevia 4DB.jpg, ''Inostrancevia, Inostrancevia alexandri'' and ''Scutosaurus'' – Late Permian, North European Russia (Northern Dvina)


Flora

Four Phytochorion, floristic provinces in the Permian are recognised, the Angaraland, Angaran, Euramerican, Gondwanan, and Cathaysian realms. The Carboniferous rainforest collapse, Carboniferous Rainforest Collapse would result in the replacement of Lycopodiopsida, lycopsid-dominated forests with Tree fern, tree-fern dominated ones during the late Carboniferous in Euramerica, and result in the differentiation of the Cathaysian floras from those of Euramerica. The southern Gondwanan floristic region was dominated by the extinct woody gymnosperm ''Glossopteris'' for most of the Permian, extending to high southern latitudes. The ecology of glossopterids has been compared to that of Taxodium distichum, bald cypress, living in mires with waterlogged soils. The tree-like calamites, distant relatives of modern Equisetum, horsetails, lived in coal swamps and grew in bamboo-like vertical thickets. A mostly complete specimen of ''Arthropitys'' from the Early Permian Chemnitz petrified forest of Germany demonstrates that they had complex branching patterns similar to modern angiosperm trees. The oldest likely record of Ginkgoales (the group containing ''Ginkgo'' and its close relatives) is ''Trichopitys, Trichopitys heteromorpha'' from the earliest Permian of France. The oldest known fossils definitively assignable to modern cycads are known from the Late Permian. In Cathaysia, where a wet tropical frost free climate prevailed, the Noeggerathiales, an extinct group of tree fern-like progymnosperms were a common component of the flora The earliest Permian (~ 298 million years ago) Cathyasian Wuda Tuff flora, representing a coal swamp community, has a upper canopy consisting of lycopsid tree ''Sigillaria,'' with a lower canopy consisting of Marattiaceae, Marattialean tree ferns, and Noeggerathiales. Early conifers appeared in the Late Carboniferous, represented by primitive walchian conifers, but were replaced with more derived Voltziales, voltzialeans during the Permian. Permian conifers were very similar morphologically to their modern counterparts, and were adapted to stressed dry or seasonally dry climactic conditions. Bennettitales, which would go on to become in widespread the Mesozoic, first appeared during the Cisuralian in China. Lyginopteridales, Lyginopterids, which had declined in the late Pennsylvanian and subsequently have a patchy fossil record, survived into the Late Permian in Cathaysia and equatorial east Gondwana.


Permian–Triassic extinction event

The Permian ended with the most extensive extinction event recorded in paleontology: the
Permian–Triassic extinction event The Permian–Triassic extinction event, also known as the P–Tr extinction, the P–T extinction, the End-Permian Extinction, and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well a ...
. Ninety to 95% of marine species became Extinction, extinct, as well as 70% of all land organisms. It is also the only known mass extinction of insects. Recovery from the Permian–Triassic extinction event was protracted; on land, ecosystems took 30 million years to recover. Trilobites, which had thrived since Cambrian times, finally became extinct before the end of the Permian. Nautiloids, a subclass of cephalopods, surprisingly survived this occurrence. There is evidence that magma, in the form of flood basalt, poured onto the Earth's surface in what is now called the
Siberian Traps The Siberian Traps (russian: Сибирские траппы, ) is a large region of volcanic rock, known as a large igneous province, in Siberia, Russia. The massive eruptive event that formed the traps is one of the largest known volcanic even ...
, for thousands of years, contributing to the environmental stress that led to mass extinction. The reduced coastal habitat and highly increased aridity probably also contributed. Based on the amount of lava estimated to have been produced during this period, the worst-case scenario is the release of enough carbon dioxide from the eruptions to raise world temperatures five degrees Celsius.Palaeos: Life Through Deep Time > The Permian Period
Accessed 1 April 2013.
Another hypothesis involves ocean venting of hydrogen sulfide gas. Portions of the Deep sea, deep ocean will periodically lose all of its dissolved oxygen allowing bacteria that live without oxygen to flourish and produce hydrogen sulfide gas. If enough hydrogen sulfide accumulates in an Anoxic event, anoxic zone, the gas can rise into the atmosphere. Oxidizing gases in the atmosphere would destroy the toxic gas, but the hydrogen sulfide would soon consume all of the atmospheric gas available. Hydrogen sulfide levels might have increased dramatically over a few hundred years. Models of such an event indicate that the gas would destroy ozone in the upper atmosphere allowing ultraviolet radiation to kill off species that had survived the toxic gas. Hydrogen sulfide#Life adapted to hydrogen sulfide, There are species that can metabolize hydrogen sulfide. Another hypothesis builds on the flood basalt eruption theory. An increase in temperature of five degrees Celsius would not be enough to explain the death of 95% of life. But such warming could slowly raise ocean temperatures until Methane clathrate, frozen methane reservoirs below the ocean floor near coastlines melted, expelling enough methane (among the most potent greenhouse gases) into the atmosphere to raise world temperatures an additional five degrees Celsius. The frozen methane hypothesis helps explain the increase in carbon-12 levels found midway in the Permian–Triassic boundary layer. It also helps explain why the first phase of the layer's extinctions was land-based, the second was marine-based (and starting right after the increase in C-12 levels), and the third land-based again. An even more speculative hypothesis is that intense radiation from a nearby supernova was responsible for the extinctions. It has been hypothesised that huge meteorite impact crater (Wilkes Land crater) with a diameter of around 500 kilometers in Antarctica represents an impact event that may be related to the extinction. The crater is located at a depth of 1.6 kilometers beneath the ice of Wilkes Land in eastern Antarctica. Scientists speculate that this impact may have caused the Permian–Triassic extinction event, although its age is bracketed only between 100 million and 500 million years ago. They also speculate that it may have contributed in some way to the separation of Australia from the Antarctic landmass, which were both part of a supercontinent called
Gondwana Gondwana () or Gondwanaland was a supercontinent that existed from the Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic (about 180 million years ago), with the opening of the Drake Passage, separating South ...
. Levels of iridium and quartz fracturing in the Permian–Triassic layer do not approach those of the Cretaceous–Paleogene boundary layer. Given that a far greater proportion of species and individual organisms became extinct during the former, doubt is cast on the significance of a meteorite impact in creating the latter. Further doubt has been cast on this theory based on fossils in Greenland that show the extinction to have been gradual, lasting about eighty thousand years, with three distinct phases. Many scientists argue that the Permian–Triassic extinction event was caused by a combination of some or all of the hypotheses above and other factors; the formation of
Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and began to break apart about 175 million years ago. In ...

Pangaea
decreased the number of coastal habitats and may have contributed to the extinction of many clades.


See also

* List of fossil sites ''(with link directory)'' * Olson's Extinction *List of Permian tetrapods


References


Further reading

*


External links


University of California offers a more modern Permian stratigraphy


* * [http://www.geo-lieven.com/erdzeitalter/perm/perm.htm Examples of Permian Fossils]
Permian (chronostratigraphy scale)
* {{Authority control Permian, Geological periods