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The Permian ( ) is a
geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth sciences, Earth scientists to describe t ...
and stratigraphic system which spans 47 million years from the end of the
Carboniferous The Carboniferous ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other ...
Period million years ago (Mya), to the beginning of the
Triassic The Triassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...

Triassic
Period 251.902 Mya. It is the last period of the
Paleozoic The Paleozoic (or Palaeozoic) Era ( ; from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its popula ...
Era; the following Triassic Period belongs to the
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles and the Age of Conifers, is the second-to-last era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy ...
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 Castle, Tarradale House, M ...

Roderick Murchison
, who named it after the region of Perm in
Russia Russia ( rus, link=no, Россия, Rossiya, ), or the Russian Federation, is a country spanning Eastern Europe Eastern Europe is the eastern region of . There is no consistent definition of the precise area it covers, partly because th ...

Russia
. 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 A clade (; from grc, , ''klados'', "bran ...
s, the
synapsid 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. Unlike other amniotes, they have a Skull#Fenestrae, temporal fenes ...

synapsid
s and the
sauropsids Sauropsida ("lizard faces") is a clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic—that is, composed of a common ancestor and al ...
(
reptile Reptiles, as most commonly defined, are the animals in the Class (biology), class Reptilia , a paraphyletic grouping comprising all amniotes except synapsids (mammals and their extinct relatives) and Aves (birds). Living reptiles comprise turtl ...

reptile
s). The world at the time was dominated by the supercontinent
Pangaea Pangaea or Pangea () was a supercontinent In 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 rock (geology) ...

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 (unit), Mya). It separated from Gondwana (beginning in t ...
and
Gondwana Gondwana () or Gondwanaland was a supercontinent In 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 rock (ge ...

Gondwana
during the Carboniferous. Pangaea was surrounded by the superocean
Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located i ...
. 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 A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

desert
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 The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous period million years ago (Mya), to 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 A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean The ocean (also the sea or the world ocean) is the body of sa ...
. 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 The Permian ( ) is a geologic period ...
, 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 Volcanic rock (often shortened to volcanics in scientific contexts) is a Rock (geology), rock formed from lava erupted from a volcano. In other ...
. It would take well into the Triassic for life to recover from this catastrophe; on land, ecosystems took 30 million years to recover.


Etymology and history

Prior to the introduction of the term "Permian", rocks of equivalent age in Germany had been named the
Rotliegend The Rotliegend, Rotliegend Group or Rotliegendes (german: the underlying red) is a lithostratigraphic through Jurassic lithostratigraphy of the Colorado Plateau area of southeastern Utah that makes up much of the famous prominent rock formations in ...
and
Zechstein The Zechstein (German language, German either from ''mine stone'' or ''tough stone'') is a unit of sedimentary rock layers of Middle to Late Permian (Guadalupian to Lopingian) age located in the Permian Basin (Europe), European Permian Basin which ...
, and in Great Britain as the
New Red Sandstone The New Red Sandstone, chiefly in British 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 rock (geology), rocks ...
. The term "Permian" was introduced into
geology Geology (from the γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is a branch of concerned with both the liquid and , the of which it is composed, and the processes by which they change over time. Geology can ...

geology
in 1841 by
Sir Roderick Impey Murchison
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 A learned society (; also known as a learned academy, scholarly society, or academic association) is an organization that exists to promote an d ...

Geological Society of London
, after extensive Russian explorations undertaken with Édouard de Verneuil in the vicinity of 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 ...
in the years 1840 and 1841. Murchison identified "vast series of beds of marl, schist, limestone, sandstone and conglomerate” that succeeded
Carboniferous The Carboniferous ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other ...
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). Gerard is a masculine forename of Proto-Germanic language, Proto-Germanic origin, variations of which exist in many Germanic and Romance languages. Like many ...
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 subjects of Russia, federal subject of Russia (a krai) that came into existence on December 1, 2005 as a result of the 2004 referendum on th ...
of Russia. Between 1853 and 1867,
Jules Marcou Jules Marcou (April 20, 1824 – April 17, 1898) was a French-Swiss-American geologist. Biography He was born at Salins, in the ''département In the administrative divisions of France, the department (french: département, ) is one of the t ...
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 A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and b ...

Mississippi River
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 drainage basin, watershed that encompasses parts of ...

Colorado River
and proposed the name "Dyassic", from "Dyas" and "Trias", though Murchison rejected this in 1871. The Permian system was controversial for over a century after its original naming, with the
United States Geological Survey The United States Geological Survey, abbreviated USGS and formerly simply known as the Geological Survey, is a scientific government agency, agency of the Federal government of the United States, United States government. The scientists of the ...
until 1941 considering the Permian a subsystem of the Carboniferous equivalent to the Mississippian and Pennsylvanian.


Geology

The Permian Period is divided into three epochs, from oldest to youngest, the Cisuralian, Guadalupian, and Lopingian. Geologists divide the rocks of the Permian into a
stratigraphic through Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approxi ...

stratigraphic
set of smaller units called
stages Stage or stages may refer to: Acting * Stage (theatre) In theatre and performing arts, the stage (sometimes referred to as the deck in stagecraft) is a designated space for the performance of theatrical production, productions. The stage s ...
, 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 stratigr ...
(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 sca ...
(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 Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which i ...
) 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.
For most of the 20th century, the Permian was divided into the Early and Late Permian, with the Kungurian being the last stage of the Early Permian. Glenister and colleagues in 1992 proposed a tripartite scheme, advocating that the Roadian-Captianian was distinct from the rest of the Late Permian, and should be regarded as a separate epoch. The tripartite split was adopted after a formal proposal by Glenister et al. (1999). Historically, most marine biostratigraphy of the Permian was based on
ammonoids Ammonoids are a group of extinct Extinction is the termination of a kind of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Li ...

ammonoids
, 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 geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes the Earth and other terrestrial planets, as well as the processes that shape them. Geologists ...
of specific species of
conodont Conodonts (Greek language, Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the Class (biology), class Conodonta. For many years, they were known only from their ...
, an enigmatic group of jawless
chordate A chordate () is an animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All ...
s with hard tooth-like oral elements. Conodonts are used as
index fossils Biostratigraphy is the branch of stratigraphy through Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic period million years ago (Year, Mya ...
for most of the Palaeozoic and the Triassic.


Cisuralian

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 Image:Albert-Auguste Cochon de Lapparent.jpg, Albert-Auguste de Lapparent Albert Auguste Cochon de Lapparent (30 December 18395 May 1908) was a France, French geologist. Life He was born at Bourges. After studying at the École polytechnique from ...
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 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 The Ilek ( kz, Елек, ''Elek'', russian: Илек) is a steppe river at the southern end of the Ural Mountains. It is a left tributary of the Ural (river), Ural and lies in Orenb ...
, 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 The Sakmara (russian: Сакмара; ba, Һаҡмар, Haqmar) is a river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and bec ...
in the southern Urals, and was coined by
Alexander Karpinsky Alexander Petrovich Karpinsky (russian: Александр Петрович Карпинский, trl. Aljeksandr Pjetrovič Karpinskij; 7 January 1847 ( NS) – 15 July 1936) was a prominent Russia Russia (russian: link=no, Россия ...
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 binodosus''. The Artinskian was named after the city of Arti in
Sverdlovsk Oblast Sverdlovsk Oblast ( rus, Свердловская область, Sverdlovskaya oblast) is a federal subject (an oblast An oblast (; ) is a type of administrative division of Belarus, Bulgaria Bulgaria (; bg, България, Bǎlgariya ...
, 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 Kungur (russian: Кунгу́р) is a types of inhabited localities in Russia, town in the southeast of Perm Krai, Russia, located in the Ural Mountains at the confluence of the rivers Iren (river), Iren and Shakva (river), Shakva with the Sylva ...
, 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 pnevi'' as the lower boundary.


Guadalupian

The Guadalupian Series is named after the
Guadalupe Mountains The Guadalupe Mountains ( es, Sierra de Guadalupe) are a mountain range located in West Texas and southeastern New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano) , seat = Santa Fe, New Mexico, Santa Fe , Lar ...
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 linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed language, sign language) and writing. Most languag ...
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 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 aserrata.'' The Capitanian is named after the Capitan Reef in the Guadalupe Mountains of Texas, named by
George Burr RichardsonGeorge Burr Richardson, MS, PhD (1872 - 1949) was a geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes the Earth and other terrestrial planets, as well as the processes that shape them. Geolog ...
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.''


Lopingian

The Lopingian was first introduced by
Amadeus William Grabau Amadeus William Grabau (January 9, 1870 – March 20, 1946) was an American geologist who worked in China. Biography Grabau's grandfathers had led dissident Lutheran immigrants from Germany to Buffalo, New York Buffalo is the List of cities ...

Amadeus William Grabau
in 1923 as the “Loping Series” after Leping,
Jiangxi Jiangxi (; ; alternately romanized as Kiangsi or Chianghsi, Gan Chinese Gan, Gann or Kan is a group of Sinitic languages The Sinitic languages, often synonymous with "Chinese languages", constitute the major branch of the Sino-Tibe ...

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 Guangxi (; alternately romanized as Kwanghsi; ; za, Gvangjsih), officially the Guangxi Zhuang Autonomous Region (GZAR), is an autonomous region An autonomous administrative division (also referred to as an autonomous area, entity, uni ...

Guangxi
, China and was ratified in 2004. The boundary is defined by the first appearance of ''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 () is a county of the prefecture-level city A prefectural-level municipality (), prefectural-level city or prefectural city is an administrative division of the People's Republic of China China (), officially the People's Republic ...
,
Zhejiang Zhejiang (, ; , Chinese postal romanization, also romanized as Chekiang) is an East China, eastern, coastal Provinces of China, province of the China, People's Republic of China. Its capital and largest city is Hangzhou. Zhejiang is bordered ...

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 parvus ''Hindeodus'' is an extinct genus of conodonts in the family Anchignathodontidae. The generic name ''Hindeodus'' is a tribute to George Jennings Hinde, a British geologist and paleontologist from the 1800s and early 1900s. The suffix -odus typica ...
''.


Regional stages

The Russian Tatarian Stage includes the Lopingian, Capitanian and part of the Wordian, while the underlying Kazanian includes the rest of the Wordian as well at the Roadian. In North America, the Permian is divided into the Wolfcampian (which includes the Nealian and the Lenoxian stages) corresponding to the Asselian through lower Kungurian; the Leonardian (Hessian and Cathedralian stages) corresponding to the upper Kungurian; the Guadalupian; and the Ochoan, corresponding to the Lopingian.


Paleogeography

During the Permian, all the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
's major landmasses were collected into a single supercontinent known as
Pangaea Pangaea or Pangea () was a supercontinent In 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 rock (geology) ...

Pangaea
, with the microcontinental terranes of
Cathaysia Cathaysia was a microcontinent Continental crustal fragments, partially synonymous with microcontinents, are pieces of continent A continent is one of several large landmasses. Generally identified by convention (norm), convention rather ...
to the east. Pangaea straddled the
equator The Equator is a circle of latitude, about in circumference, that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the N ...

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 Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located i ...
", the "universal sea"), and the
Paleo-Tethys Ocean The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean The ocean (also the or the world ocean) is the body of that covers approximately 70.8% of the surface of and contains 97% of . Another definition is "any of the large bodies of water ...
, a large ocean that existed between Asia and Gondwana. The Cimmeria continent
rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear Fault (geology), downfaulted depression, called a graben, or more commonly ...

rift
ed away from
Gondwana Gondwana () or Gondwanaland was a supercontinent In 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 rock (ge ...

Gondwana
and drifted north to
Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea Pangaea or Pangea () was a supercontinent In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("s ...
, causing the Paleo-Tethys Ocean to shrink. A new ocean was growing on its southern end, the
Neotethys Ocean Image:Laurasia-Gondwana.svg, 250px, First phase of the Tethys Ocean's forming: the (first) Tethys Sea starts dividing Pangaea into two supercontinents, Laurasia and Gondwana. The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys ...
, an ocean that would dominate much of the
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles and the Age of Conifers, is the second-to-last era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy ...
Era. The Central Pangean Mountains, which began forming due to the collision of Laurasia and Gondwana during the Carboniferous, reached their maximum height during the early Permian around 295 million years ago, comparable to the present
Himalayas The Himalayas, or Himalaya (; Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language of South Asia that belongs to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It ar ...

Himalayas
, but became heavily eroded as the Permian progressed. The
Kazakhstania Kazakhstania ( kk, Qazaqstaniya), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia Central Asia is a region in Asia which stretches from the Caspian Sea in the west to China and Mongolia in the east, and from ...
block collided with Baltica during the Cisuralian, while the
North China Craton The North China Craton is a continental crustal block with one of Earth's most complete and complex records of igneous Igneous rock (derived from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic ...

North China Craton
, the South China Block and
Indochina Mainland Southeast Asia, also known as the Indochinese Peninsula or Indochina, is the continental portion of Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is t ...
fused to each other and Pangea by the end of the Permian. Large continental landmass interiors experience climates with extreme variations of heat and cold ("
continental climate Continental climates often have a significant annual variation in temperature (hot summers and cold winters). They tend to occur in the middle latitudes (40 to 55 north), within large landmasses where prevailing winds blow overland, and temperat ...
") and
monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation In meteorology Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology ...

monsoon
conditions with highly seasonal rainfall patterns.
Desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

Desert
s seem to have been widespread on Pangaea. Such dry conditions favored
gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also ...
s, plants with seeds enclosed in a protective cover, over plants such as
fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia art ...

fern
s that disperse
spore In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...
s in a wetter environment. The first modern trees (
conifers Conifers are a group of cone-bearing seed plants The spermatophytes (; ), also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plant Plants are predominantly photosynthetic Photosynthesi ...

conifers
,
ginkgo ''Ginkgo'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circums ...

ginkgo
s and
cycad :''For the insect, see Cicada.'' Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious ...

cycad
s) 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 ...
(where Perm itself is located), China, and the southwest of North America, including the Texas red beds. The Permian Basin in the
U.S. state In the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state ...
s of
Texas Texas (, ; Spanish Spanish may refer to: * Items from or related to Spain: **Spaniards, a nation and ethnic group indigenous to Spain **Spanish language **Spanish cuisine Other places * Spanish, Ontario, Canada * Spanish River (disambigu ...

Texas
and
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Greater Albuquerque , OfficialLang = None , Languages = English English usually refer ...

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 The Devonian ( ) is a geologic period and system of the Paleozoic The Paleozoic (or Palaeozoic) Era ( ; from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the H ...
. At the beginning of the Pennsylvanian around 323 million years ago, glaciers began to form around the
South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies on the ...
, which would grow to cover a vast area. This area extended from the southern reaches of the
Amazon basin The Amazon Basin is the part of South America South America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven ...
and covered large areas of
southern Africa Southern Africa is the south South is one of the cardinal directions or compass points. South is the opposite of north and is perpendicular to the east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Pr ...
, as well as most of Australia and Antarctica.
Cyclothems In geology, cyclothems are alternating stratigraphy, stratigraphic sequences of Marine (ocean), marine and non-marine sediments, sometimes interbedded with coal seams. Historically, the term was defined by the European coal geologists who worked ...

Cyclothems
indicate that the size of the glaciers were controlled by
Milankovitch cycles Milankovitch cycles describe the collective effects of changes in the Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of contine ...

Milankovitch cycles
akin to recent
ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents an ...

ice age
s, with
glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the ...
s and
interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial period A glacial period (alternatively glacial or ...
s. 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 The Transantarctic Mountains (abbreviated TAM) comprise a mountain range A mountain range is a series of mountains ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarit ...

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 A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean The ocean (also the sea or the world ocean) is the body of sa ...
. 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 Volcanic rock (often shortened to volcanics in scientific contexts) is a Rock (geology), rock formed from lava erupted from a volcano. In other ...
, which released more than 5 teratonnes of CO2 , more than doubling atmospheric carbon dioxide concentrations.


Life


Marine invertebrates

Permian marine deposits are rich in
fossil A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication used by humans, inc ...

fossil
mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda. The members are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil species is es ...

mollusks
,
echinoderm An echinoderm () is any member of the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of ...
s, and
brachiopod Brachiopods (), phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a ...
s. Brachiopods were highly diverse during the Permian. The extinct order Productida was the predominant group of Permian brachiopods, accounting for up to about half of all Permian brachiopod genera. Conodonts experienced their lowest diversity of their entire evolutionary history during the Permian. Amongst
ammonoids Ammonoids are a group of extinct Extinction is the termination of a kind of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Li ...

ammonoids
, Goniatitida were a major group during the Early-Mid Permian, but declined during the Late Permian. Members of the order
Prolecanitida Prolecanitida is an order of extinct ammonoidea, ammonoid cephalopods with discoidal to thinly lenticular shells with goniatitic or ceratitic sutures and which retained the simple retrochoanitic siphuncle with backward extending septal necks. As ty ...
were less diverse. The Ceratitida originated from the family Daraelitidae within Prolecanitida during the mid-Permian, and extensively diversified during the Late Permian. Only three families of trilobite are known from the Permian, Proetidae, Brachymetopidae and Phillipsiidae. Diversity, origination and extinction rates during the Early Permian were low. Trilobites underwent a diversification during the Kungurian-Wordian, the last in their evolutionary history, before declining during the Late Permian. By the Changhsingian, only a handful (4-6) genera remained.


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 In 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 rock (geology) ...

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
conifers Conifers are a group of cone-bearing seed plants The spermatophytes (; ), also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plant Plants are predominantly photosynthetic Photosynthesi ...

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 The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean The ocean (also the or the world ocean) is the body of that covers approximately 70.8% of the surface of and contains 97% of . Another definition is "any of the large bodies of water ...
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
cycad :''For the insect, see Cicada.'' Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious ...

cycad
s also appeared during this period.


Insects

Insects, which had first appeared and become abundant during the preceding Carboniferous, experienced a dramatic increase in diversification during the Early Permian. Towards the end of the Permian, there was a substantial drop in both origination and extinction rates. The dominant insects during the Permian Period were early representatives of Palaeoptera, Paleoptera, Polyneoptera, and Paraneoptera. Palaeodictyopteroidea, which had represented the dominant group of insects during the Carboniferous, declined during the Permian. This is likely due to competition by Hemiptera, due to their similar mouthparts and therefore ecology. Primitive relatives of Damselfly, damselflies and Dragonfly, dragonflies (Meganisoptera), which include the largest flying insects of all time, also declined during the Permian. Endopterygota, Holometabola, the largest group of modern insects, also diversified during this time. The earliest known beetles, appear at the beginning of the Permian. Early beetles such as members of Permocupedidae likely xylophagous feeding on decaying wood. Several lineages, such as Schizophoridae expanded into aquatic habitats by the Late Permian. Members of the modern orders Archostemata and Adephaga are known from the Late Permian. Complex wood boring traces found in the Late Permian of China suggest that members of Polyphaga, the most diverse group of modern beetles, were also present in the Permian.


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 primitive pelycosaur
synapsid 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. Unlike other amniotes, they have a Skull#Fenestrae, temporal fenes ...

synapsid
s 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. A faunal turnover occurred at the transition between the Cisuralian and Guadalupian, with the decline of amphibians and the replacement of pelycosaurs with more advanced therapsids. Owing to the end of terrestrial deposition around the end of the Cisuralian in North America and the beginning of the deposition of terrestrial sediments in Russia during the early Guadalupian, a continuous record of the transition is not preserved. Uncertain dating has led to suggestions that there is a global hiatus in the terrestrial fossil record during the late Kungurian and early Roadian, referred to as "Olson's Gap" that obscures the nature of the transition. Other proposals have suggested that the North American and Russian records overlap, with the latest terrestrial North American deposition occurring during the Roadian, suggesting that there was an extinction event, dubbed "Olson's Extinction, Olsons Extinction". The Middle Permian faunas of South Africa and Russia are dominated by 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 sabertoothed gorgonopsians and herbivorous beaked dicynodonts, alongside large herbivorous pareiasaur Parareptilia, parareptiles. The Archosauromorpha, the group of reptiles that would give rise to the pseudosuchians, dinosaurs, and pterosaurs in the following Triassic, first appeared and diversified during the Late Permian, including the first appearance of the Archosauriformes during the latest Permian. Cynodonts, the group of therapsids ancestral to modern mammals, first appeared and gained a worldwide distribution during the Late Permian. Another group of therapsids, the therocephalians (such as ''Lycosuchus''), arose in the Middle Permian. There were no flying vertebrates, though the extinct lizard like reptile family Weigeltisauridae from the Late Permian had extendable wings like modern Draco (lizard), gliding lizards, and are the oldest known gliding vertebrates. 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 (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)


Fish

The diversity of fish during the Permian is relatively low compared to the following Triassic. The dominant group of Bony Fishes, bony fishes during the Permian were the "Paleopterygii" a paraphyletic grouping of Actinopterygii that lie outside of Neopterygii. The earliest unequivocal members of Neopterygii appear during the Early Triassic, but a Permian origin is suspected. The diversity of coelacanths is relatively low throughout the Permian in comparison to other marine fishes, though there is an increase in diversity during the terminal Permian (Changhsingian), corresponding with the highest diversity in their evolutionary history during the Early Triassic. Diversity of freshwater fish faunas was generally low and dominated by lungfish and "Paleopterygians". The last common ancestor of all living lungfish is thought to have existed during the Early Permian. Though the fossil record is fragmentary, lungfish appear to have undergone an evolutionary diversification and size increase in freshwater habitats during the Early Permian, but subsequently declined during the middle and late Permian. Xenacanthiformes, an extinct group of sharks, were also common in freshwater habitats, and represented the apex predators of freshwater ecosystems. Permian chondrichthyan faunas are poorly known. Members of the chondrichthyan clade Holocephali, which contains living chimaeras, reached their apex of diversity during the Carboniferous-Permian, the most famous Permian representative being the "buzz-saw shark" ''Helicoprion,'' known for its unusual spiral shaped spiral tooth whorl in the lower jaw. Hybodontiformes, Hybodonts were widespread and abundant members of marine and freshwater faunas throughout the Permian.


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 Gondwanan floristic region was dominated by Glossopteridales, a group of woody gymnosperm plants, for most of the Permian, extending to high southern latitudes. The ecology of the most prominent glossopterid, ''Glossopteris'', 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
cycad :''For the insect, see Cicada.'' Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious ...

cycad
s 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 an 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 climatic 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 The Permian ( ) is a geologic period ...
. 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 Volcanic rock (often shortened to volcanics in scientific contexts) is a Rock (geology), rock formed from lava erupted from a volcano. In other ...
, 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.


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