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114-544: The eruptions continued for roughly two million years and spanned the Permian – Triassic boundary, or P–T boundary, which occurred around 251.9 million years ago. The Siberian Traps are believed to be the primary cause of the Permian–Triassic extinction event , the most severe extinction event in the geologic record. Subsequent periods of Siberian Traps activity have been linked to a number of smaller biotic crises, including

228-901: A century after its original naming, with the United States Geological Survey until 1941 considering the Permian a subsystem of the Carboniferous equivalent to the Mississippian and Pennsylvanian . 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 set of smaller units called stages , each formed during corresponding time intervals called ages. Stages can be defined globally or regionally. For global stratigraphic correlation,

342-630: 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. 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. The Roadian

456-630: A coal swamp community, has an upper canopy consisting of lycopsid tree Sigillaria , with a lower canopy consisting of Marattialean tree ferns, and Noeggerathiales. Early conifers appeared in the Late Carboniferous, represented by primitive walchian conifers, but were replaced with more derived 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. The increasing aridity, especially at low latitudes, facilitated

570-541: 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 Paleoptera , Polyneoptera , and Paraneoptera . Palaeodictyopteroidea , which had represented the dominant group of insects during the Carboniferous, declined during

684-481: 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. Embolomeres , a group of aquatic crocodile-like limbed vertebrates that are reptilliomorphs under some phylogenies. They previously had their last records in the Cisuralian, are now known to have persisted into

798-430: A process known as fishing down the food web . However, more recent work finds no relation between economic value and trophic level; and that mean trophic levels in catches, surveys and stock assessments have not in fact declined, suggesting that fishing down the food web is not a global phenomenon. However Pauly et al . note that trophic levels peaked at 3.4 in 1970 in the northwest and west-central Atlantic, followed by

912-525: A protective cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees ( conifers , ginkgos and cycads ) appeared in the Permian. Three general areas are especially noted for their extensive Permian deposits—the Ural Mountains (where Perm itself is located), China, and the southwest of North America, including the Texas red beds. The Permian Basin in

1026-544: A short period of time with rapid rock solidification/cooling. Studies confirmed that samples of gabbro and basalt from the same time period of the Permian–Triassic event from the other southern regions also matched the age of samples within the Siberian Traps. This confirms the assumption of the linkage between the age of volcanic rocks within the Siberian Traps, along with rock samples from other southern regions to

1140-411: A subsequent decline to 2.9 in 1994. They report a shift away from long-lived, piscivorous, high-trophic-level bottom fishes, such as cod and haddock, to short-lived, planktivorous, low-trophic-level invertebrates (e.g., shrimp) and small, pelagic fish (e.g., herring). This shift from high-trophic-level fishes to low-trophic-level invertebrates and fishes is a response to changes in the relative abundance of

1254-481: A timeline based on when they crystallized. The CA-TIMS technique , a chemical abrasion age-dating technique that eliminates variability in accuracy due to lead depletion in zircon over time, was then used to accurately determine the age of the zircons found in the Siberian Traps. Eliminating the variability due to lead, the CA-TIMS age-dating technique allowed uranium within the zircon to be the centre focus in linking

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1368-642: 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 ". The Middle Permian faunas of South Africa and Russia are dominated by therapsids, most abundantly by

1482-459: Is because there is a consistent increase in the nitrogen isotopic composition at each trophic level caused by fractionations that occur with the synthesis of biomolecules; the magnitude of this increase in nitrogen isotopic composition is approximately 3–4‰. In fisheries, the mean trophic level for the fisheries catch across an entire area or ecosystem is calculated for year y as: where Y i y {\displaystyle Y_{iy}}

1596-428: Is called tritrophic interaction. Ecologists often restrict their research to two trophic levels as a way of simplifying the analysis; however, this can be misleading if tritrophic interactions (such as plant–herbivore–predator) are not easily understood by simply adding pairwise interactions (plant-herbivore plus herbivore–predator, for example). Significant interactions can occur between the first trophic level (plant) and

1710-663: 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 Richardson in 1904, and first used in a chronostratigraphic sense by Glenister and Furnish in 1961 as a substage of the Guadalupian Stage. The Capitanian was ratified as an international stage by the ICS in 2001. The GSSP for

1824-589: Is derived from the Swedish word for stairs ("trappa") and refers to the step-like hills forming the landscape of the region. The source of the Siberian Traps basaltic rock has been attributed to a mantle plume , which rose until it reached the bottom of the Earth's crust , producing volcanic eruptions through the Siberian Craton . It has been suggested that, as the Earth's lithospheric plates moved over

1938-414: Is stable (zero) over periods of time when changes in trophic levels are matched by appropriate changes in the catch in the opposite direction. The index increases if catches increase for any reason, e.g. higher fish biomass, or geographic expansion. Such decreases explain the "backward-bending" plots of trophic level versus catch originally observed by Pauly and others in 1998. One aspect of trophic levels

2052-437: Is the annual catch of the species or group i in year y , and   T L i   {\displaystyle \ TL_{i}\ } is the trophic level for species i as defined above. Fish at higher trophic levels usually have a higher economic value, which can result in overfishing at the higher trophic levels. Earlier reports found precipitous declines in mean trophic level of fisheries catch, in

2166-420: Is the mean trophic level of the catch at year y , Y 0 {\displaystyle Y_{0}} is the catch, T L 0 {\displaystyle TL_{0}} the mean trophic level of the catch at the start of the series being analyzed, and T E {\displaystyle TE} is the transfer efficiency of biomass or energy between trophic levels. The FiB index

2280-575: Is the sixth and last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison , who named it after the region of Perm in Russia . The Permian witnessed the diversification of the two groups of amniotes , the synapsids and the sauropsids ( reptiles ). The world at

2394-452: 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. Conodonts experienced their lowest diversity of their entire evolutionary history during the Permian. Permian chondrichthyan faunas are poorly known. Members of

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2508-599: The International Commission on Stratigraphy (ICS) ratify global stages based on a Global Boundary Stratotype Section and Point (GSSP) from a single formation (a stratotype ) identifying the lower boundary of the stage. The ages of the Permian, from youngest to oldest, are: For most of the 20th century, the Permian was divided into the Early and Late Permian, with the Kungurian being the last stage of

2622-726: The North China Craton , the South China Block and Indochina fused to each other and Pangea by the end of the Permian. The Zechstein Sea , a hypersaline epicontinental sea , existed in what is now northwestern Europe. 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

2736-644: The Paleo-Tethys Ocean , a large ocean that existed between Asia and Gondwana. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia , causing the Paleo-Tethys Ocean to shrink. A new ocean was growing on its southern end, the Neotethys Ocean , an ocean that would dominate much of the Mesozoic Era. A magmatic arc, containing Hainan on its southwesternmost end, began to form as Panthalassa subducted under

2850-715: The Permian–Triassic extinction event (colloquially known as the Great Dying), the largest mass extinction in Earth's history (which is the last of the three or four crises that occurred in the Permian), in which nearly 81% of marine species and 70% of terrestrial species died out, associated with the eruption of the Siberian Traps . It took well into the Triassic for life to recover from this catastrophe; on land, ecosystems took 30 million years to recover. Prior to

2964-553: The Smithian-Spathian , Olenekian-Anisian, Middle-Late Anisian, and Anisian-Ladinian extinction events. Large volumes of basaltic lava covered a large expanse of Siberia in a flood basalt event. Today, the area is covered by about 7 million km (3 million sq mi) of basaltic rock, with a volume of around 4 million km (1 million cu mi). The term "trap" has been used in geology since 1785–1795 for such rock formations . It

3078-549: The Sydney Basin , and palaeoclimatic models of the Earth's climate based on the behaviour of modern weather patterns showing that such a megamonsoon would occur given the continental arrangement of the Permian. The aforementioned increasing equatorial aridity was likely driven by the development and intensification of this Pangaean megamonsoon. Permian marine deposits are rich in fossil mollusks , brachiopods , and echinoderms . Brachiopods were highly diverse during

3192-447: 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. 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, culminating in the lowest sea level of the entire Palaeozoic at around present sea level during

3306-399: The Ural Mountains in the years 1840 and 1841. Murchison identified "vast series of beds of marl , schist , limestone , sandstone and conglomerate" that succeeded Carboniferous strata in the region. Murchison, in collaboration with Russian geologists, named the period after the surrounding Russian region of Perm, which takes its name from the medieval kingdom of Permia that occupied

3420-557: The impact that formed the Wilkes Land crater in Antarctica , which is estimated to have occurred around the same time and been nearly antipodal to the traps. The main source of rock in this formation is basalt, but both mafic and felsic rocks are present, so this formation is officially called a Flood Basalt Province. The inclusion of mafic and felsic rock indicates multiple other eruptions that occurred and coincided with

3534-577: 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

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3648-605: The Asselian, Sakmarian, and Artinskian stages. The Kungurian was later added to conform to the Russian "Lower Permian". Albert Auguste Cochon de Lapparent 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

3762-691: The Cisuralian. Another cool period began around the middle Capitanian. This cool period, lasting for 3-4 Myr, was known as the Kamura Event. It 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 . This interval of rapid climate change was responsible for the Capitanian mass extinction event. During

3876-450: The Cisuralian. 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. A faunal turnover occurred around the transition between the Cisuralian and Guadalupian, with the decline of amphibians and the replacement of pelycosaurs (a paraphyletic group) with more advanced therapsids , although

3990-500: The Early Permian Chemnitz petrified forest of Germany demonstrates that they had complex branching patterns similar to modern angiosperm trees. By the Late Permian, high thin forests had become widespread across the globe, as evidenced by the global distribution of weigeltisaurids. The oldest likely record of Ginkgoales (the group containing Ginkgo and its close relatives) is Trichopitys heteromorpha from

4104-599: The Early Permian. Glenister and colleagues in 1992 proposed a tripartite scheme, advocating that the Roadian-Capitanian 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 ; however, ammonoid localities are rare in Permian stratigraphic sections, and species characterise relatively long periods of time. All GSSPs for

4218-568: 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

4332-431: The Early Triassic. The volcanism that occurred in the Siberian Traps resulted in copious amounts of magma being ejected from the Earth's crust—leaving permanent traces of rock from the same time period of the mass extinction that can be examined today. More specifically, zircon is found in some of the volcanic rocks. To further the accuracy of the age of the zircon, several varying aged pieces of zircon were organized into

4446-482: The Earth's carbon cycle based on observations such as a significant increase of inorganic carbon reservoirs in marine environments. Recent research has highlighted the impact of vegetative deposition in the preceding Carboniferous period on the severity of the disruption to the carbon cycle. This extinction event, also colloquially called the Great Dying, affected all life on Earth, and is estimated to have led to

4560-472: 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 by the Late Permian. 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

4674-617: The Late Permian. By the Changhsingian, only a handful (4-6) genera remained. Corals exhibited a decline in diversity over the course of the Middle and Late Permian. Terrestrial life in the Permian included diverse plants, fungi , arthropods , and various types of tetrapods . The period saw a massive desert covering the interior of 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,

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4788-623: The Lopingian in China. Modern amphibians ( lissamphibians ) are suggested to have originated during Permian, descending from a lineage of dissorophoid temnospondyls or lepospondyls . The diversity of fish during the Permian is relatively low compared to the following Triassic. The dominant group of 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

4902-605: 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 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

5016-598: 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. The Wuchiapinginan and Changhsingian were first introduced in 1962, by J. Z. Sheng as the "Wuchiaping Formation" and "Changhsing Formation" within

5130-514: 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 gliding lizards , and are the oldest known gliding vertebrates. Permian stem-amniotes consisted of lepospondyli and batrachosaurs , according to some phylogenies; according to others, stem-amniotes are represented only by diadectomorphs . Temnospondyls reached

5244-598: 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 synapsids including the herbivorous edaphosaurids , and carnivorous sphenacodontids , diadectids and amphibians . Early Permian reptiles, such as acleistorhinids , were mostly small insectivores. Synapsids (the group that would later include mammals) thrived and diversified greatly during

5358-514: The Ochoan, corresponding to the Lopingian. During the Permian, all the Earth 's major landmasses were collected into a single supercontinent known as Pangaea , with the 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 ", the "universal sea"), and

5472-620: The Permian are based around the first appearance datum of specific species of conodont , an enigmatic group of jawless chordates with hard tooth-like oral elements. Conodonts are used as index fossils 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 Kazakhstan. The name was proposed by J. B. Waterhouse in 1982 to comprise

5586-582: The Permian, representing up to a third of all insects at some localities. Mecoptera (sometimes known as scorpionflies) first appeared during the Early Permian, going on to become diverse during the Late Permian. Some Permian mecopterans, like Mesopsychidae have long proboscis that suggest they may have pollinated gymnosperms. The earliest known beetles appeared at the beginning of the Permian. Early beetles such as members of Permocupedidae were likely xylophagous , feeding on decaying wood. Several lineages such as Schizophoridae expanded into aquatic habitats by

5700-540: The Permian-Triassic boundary, corresponding to the eruption of the Siberian Traps , which released more than 5 teratonnes of CO 2 , more than doubling the atmospheric carbon dioxide concentration. A -2% δ O excursion signifies the extreme magnitude of this climatic shift. This extremely rapid interval of greenhouse gas release caused the Permian-Triassic mass extinction, as well as ushering in an extreme hothouse that persisted for several million years into

5814-508: The Permian. Xenacanthiformes , another extinct group of shark-like chondrichthyans, were common in freshwater habitats, and represented the apex predators of freshwater ecosystems. Four floristic provinces in the Permian are recognised, the Angaran , Euramerican, Gondwanan, and Cathaysian realms. The Carboniferous Rainforest Collapse would result in the replacement of lycopsid -dominated forests with tree-fern dominated ones during

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5928-543: The Permian. The end of the Early Permian ( Cisuralian ) saw a major faunal turnover, with most lineages of primitive " pelycosaur " synapsids becoming extinct, being replaced by more advanced therapsids . The end of the Capitanian Stage of the Permian was marked by the major Capitanian mass extinction event , associated with the eruption of the Emeishan Traps . The Permian (along with the Paleozoic) ended with

6042-524: The Permian. The extinct order Productida was the predominant group of Permian brachiopods, accounting for up to about half of all Permian brachiopod genera. Brachiopods also served as important ecosystem engineers in Permian reef complexes. Amongst ammonoids , Goniatitida were a major group during the Early-Mid Permian, but declined during the Late Permian. Members of the order Prolecanitida were less diverse. The Ceratitida originated from

6156-515: The Permian. This is likely due to competition by Hemiptera , due to their similar mouthparts and therefore ecology. Primitive relatives of damselflies and dragonflies ( Meganisoptera ), which include the largest flying insects of all time, also declined during the Permian. Holometabola , the largest group of modern insects, also diversified during this time. " Grylloblattidans ", an extinct group of winged insects thought to be related to modern ice crawlers , reached their apex of diversity during

6270-407: The Permian–Triassic mass extinction event. The giant Norilsk - Talnakh nickel – copper – palladium deposit formed within the magma conduits in the most complete part of the Siberian Traps. It has been linked to the Permian–Triassic extinction event, which occurred approximately 251.4 million years ago, based on large amounts of nickel and other elements found in rock beds that were laid down after

6384-434: The Siberian Traps were dated based on argon isotope 40 and argon isotope 39 age-dating methods. Feldspar and biotite was specifically used to focus on the samples' age and duration of the presence of magma from the volcanic event in the Siberian Traps. The majority of the basalt and gabbro samples dated to 250 million years ago, covered a surface area of five million square kilometres on the Siberian Traps and occurred within

6498-654: 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 , 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 ,

6612-736: 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

6726-476: The Wuchiapingian, followed by a slight rise during the Changhsingian. The Permian was cool in comparison to most other geologic time periods, with modest pole to Equator temperature gradients. At the start of the Permian, the Earth was still in the Late Paleozoic icehouse (LPIA), which began in the latest Devonian and spanned the entire Carboniferous period, with its most intense phase occurring during

6840-506: 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. Another hypothesis involves ocean venting of hydrogen sulfide gas. Portions of the 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 zone ,

6954-470: 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 ginkgos and cycads also appeared during this period. Insects, which had first appeared and become abundant during the preceding Carboniferous, experienced

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7068-483: The average trophic level of human beings at 2.21, similar to pigs or anchovies. This is only an average, and plainly both modern and ancient human eating habits are complex and vary greatly. For example, a traditional Inuit living on a diet consisting primarily of seals would have a trophic level of nearly 5. In general, each trophic level relates to the one below it by absorbing some of the energy it consumes, and in this way can be regarded as resting on, or supported by,

7182-591: The base of the Asselian is located in the Aidaralash River valley near Aqtöbe , 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

7296-418: The base of the Capitanian 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 introduced 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

7410-459: 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

7524-532: The biomass at any one moment may be low; for example, phytoplankton (producer) biomass can be low compared to the zooplankton (consumer) biomass in the same area of ocean. The efficiency with which energy or biomass is transferred from one trophic level to the next is called the ecological efficiency . Consumers at each level convert on average only about 10% of the chemical energy in their food to their own organic tissue (the ten-per cent law ). For this reason, food chains rarely extend for more than 5 or 6 levels. At

7638-506: The bobcat eats rabbits, but the mountain lion eats both bobcats and rabbits. Animals can also eat each other; the bullfrog eats crayfish and crayfish eat young bullfrogs. The feeding habits of a juvenile animal, and, as a consequence, its trophic level, can change as it grows up. The fisheries scientist Daniel Pauly sets the values of trophic levels to one in plants and detritus, two in herbivores and detritivores (primary consumers), three in secondary consumers, and so on. The definition of

7752-511: The case of marine ecosystems, the trophic level of most fish and other marine consumers takes a value between 2.0 and 5.0. The upper value, 5.0, is unusual, even for large fish, though it occurs in apex predators of marine mammals, such as polar bears and orcas. In addition to observational studies of animal behavior, and quantification of animal stomach contents, trophic level can be quantified through stable isotope analysis of animal tissues such as muscle , skin , hair , bone collagen . This

7866-769: The chain can form either a one-way flow or a part of a wider food "web". Ecological communities with higher biodiversity form more complex trophic paths. The word trophic derives from the Greek τροφή (trophē) referring to food or nourishment. The concept of trophic level was developed by Raymond Lindeman (1942), based on the terminology of August Thienemann (1926): "producers", "consumers", and "reducers" (modified to "decomposers" by Lindeman). The three basic ways in which organisms get food are as producers, consumers, and decomposers. Trophic levels can be represented by numbers, starting at level 1 with plants. Further trophic levels are numbered subsequently according to how far

7980-502: 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. Hybodonts , a group of shark-like chondrichthyans, were widespread and abundant members of marine and freshwater faunas throughout

8094-636: The climate became notably more arid at the end of the Carboniferous and beginning of the Permian. Nonetheless, temperatures continued to cool during most of the Asselian and Sakmarian, during which the LPIA peaked. By 287 million years ago, temperatures warmed and the South Pole ice cap retreated in what was known as the Artinskian Warming Event (AWE), though glaciers remained present in the uplands of eastern Australia, and perhaps also

8208-689: The conodont Hindeodus parvus . 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 as the Roadian. In North America, the Permian is divided into the Wolfcampian (which includes the Nealian and the Lenoxian stages); the Leonardian (Hessian and Cathedralian stages); the Guadalupian; and

8322-552: The continental interior by the more advanced seed ferns and early conifers as a result of the Carboniferous rainforest collapse . At the close of the Permian, lycopod and equisete swamps reminiscent of Carboniferous flora survived only in Cathaysia , a series of equatorial islands in the Paleo-Tethys Ocean that later would become South China . The Permian saw the radiation of many important conifer groups, including

8436-633: The decline of early synapsid clades was apparently a slow event that lasted about 20 Ma, from the Sakmarian to the end of the Kungurian . Predator-prey interactions among terrestrial synapsids became more dynamic. If terrestrial deposition ended around the end of the Cisuralian in North America and began in Russia during the early Guadalupian, a continuous record of the transition is not preserved. Uncertain dating has led to suggestions that there

8550-470: 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 parareptiles . The Archosauromorpha , the group of reptiles that would give rise to

8664-465: 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

8778-573: The early Wuchiapingian, following the emplacement of the Emeishan Traps, global temperatures declined as carbon dioxide was weathered out of the atmosphere by the large igneous province's emplaced basalts. The late Wuchiapingian saw the finale of the Late Palaeozoic Ice Age, when the last Australian glaciers melted. The end of the Permian is marked by a temperature excursion, much larger than the Emeishan Thermal Excursion, at

8892-530: The end of a food chain. Thus food chains start with primary producers and end with decay and decomposers. Since decomposers recycle nutrients, leaving them so they can be reused by primary producers, they are sometimes regarded as occupying their own trophic level. The trophic level of a species may vary if it has a choice of diet. Virtually all plants and phytoplankton are purely phototrophic and are at exactly level 1.0. Many worms are at around 2.1; insects 2.2; jellyfish 3.0; birds 3.6. A 2013 study estimates

9006-431: 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 , 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

9120-540: The end of the Spathian, and the first coals at these latitudes did not appear until the Carnian , around 15 million years after their end-Permian disappearance. These signals suggest equatorial temperatures exceeded their thermal tolerance for many marine vertebrates at least during two thermal maxima, whereas terrestrial equatorial temperatures were sufficiently severe to suppress plant and animal abundance during most of

9234-433: The exception being intermittent mass extinction events. Food webs largely define ecosystems, and the trophic levels define the position of organisms within the webs. But these trophic levels are not always simple integers, because organisms often feed at more than one trophic level. For example, some carnivores also eat plants, and some plants are carnivores. A large carnivore may eat both smaller carnivores and herbivores;

9348-407: The extinction occurred. The method used to correlate the extinction event with the surplus amount of nickel located in the Siberian Traps compares the timeline of the magmatism within the traps and the timeline of the extinction itself. Before the linkage between magmatism and the extinction event was discovered, it was hypothesized that the mass extinction and volcanism occurred at the same time due to

9462-415: The extinction of about 81% of all marine species and 70% of terrestrial vertebrate species living at the time. Some of the disastrous events that affected the Earth continued to repeat themselves five to six million years after the initial extinction occurred. Over time a small portion of the life that survived the extinction was able to repopulate and expand starting with low trophic levels (producers) until

9576-399: The extinction that did not exist beforehand. Palaeontological evidence further indicates that the global distribution of tetrapods vanished between latitudes approximating 40° south to 30° north, with very rare exceptions in the region of Pangaea that is today Utah . This tetrapod gap of equatorial Pangaea coincides with an end-Permian to Middle Triassic global "coal gap" that indicates

9690-580: 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

9804-429: 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

9918-447: The higher trophic levels (consumers) were able to be re-established. Calculations of sea water temperature from δ O measurements indicate that at the peak of the extinction, the Earth underwent lethally hot global warming, in which equatorial ocean temperatures exceeded 40 °C (104 °F). It took roughly eight to nine million years for any diverse ecosystem to be re-established; however, new classes of animals were established after

10032-721: The introduction of the term Permian , rocks of equivalent age in Germany had been named the Rotliegend and Zechstein , and in Great Britain as the New Red Sandstone . The term Permian was introduced into geology in 1841 by Sir Roderick Impey Murchison , president of the Geological Society of London , after extensive Russian explorations undertaken with Édouard de Verneuil in the vicinity of

10146-748: 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 bald cypress , living in mires with waterlogged soils. The tree-like calamites , distant relatives of modern horsetails , lived in coal swamps and grew in bamboo -like vertical thickets. A mostly complete specimen of Arthropitys from

10260-540: The latter part of the Pennsylvanian epoch. A significant trend of increasing aridification can be observed over the course of the Cisuralian. Early Permian aridification was most notable in Pangaean localities at near-equatorial latitudes. Sea levels also rose notably in the Early Permian as the LPIA slowly waned. At the Carboniferous-Permian boundary, a warming event occurred. In addition to becoming warmer,

10374-551: The linkages in rock composition. 67°N 90°E  /  67°N 90°E  / 67; 90 Permian The Permian ( / ˈ p ɜːr m i . ə n / PUR -mee-ən ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It

10488-524: The loss of peat swamps. Peat formation, a product of high plant productivity, was reestablished only in the Anisian stage of the Triassic, and even then only in high southern latitudes, although gymnosperm forests appeared earlier (in the Early Spathian ), but again only in northern and southern higher latitudes. In equatorial Pangaea, the establishment of conifer-dominated forests was not until

10602-409: The lowest trophic level (the bottom of the food chain), plants convert about 1% of the sunlight they receive into chemical energy. It follows from this that the total energy originally present in the incident sunlight that is finally embodied in a tertiary consumer is about 0.001% Both the number of trophic levels and the complexity of relationships between them evolve as life diversifies through time,

10716-447: The major questions is whether the Siberian Traps were directly responsible for the Permian–Triassic mass extinction event that occurred 250 million years ago, or if they were themselves caused by some other, larger event, such as an asteroid impact . One hypothesis put forward is that the volcanism triggered the growth of Methanosarcina , a microbe that then emitted large amounts of methane into Earth's atmosphere, ultimately altering

10830-704: The mantle plume (the Iceland plume ), the plume produced the Siberian Traps in the Permian and Triassic periods, after earlier producing the Viluy Traps to the east, and later going on to produce volcanic activity on the floor of the Arctic Ocean in the Jurassic and Cretaceous , and then generating volcanic activity in Iceland. Other plate tectonic causes have also been suggested. Another possible cause may be

10944-455: The most extensive extinction event recorded in paleontology : the Permian–Triassic extinction event . 90 to 95% of marine species became 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

11058-473: 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

11172-414: The mountainous regions of far northern Siberia. Southern Africa also retained glaciers during the late Cisuralian in upland environments. The AWE also witnessed aridification of a particularly great magnitude. In the late Kungurian, cooling resumed, resulting in a cool glacial interval that lasted into the early Capitanian, though average temperatures were still much higher than during the beginning of

11286-713: The next geologic epoch, the Triassic. The Permian climate was also extremely seasonal and characterised by megamonsoons , which produced high aridity and extreme seasonality in Pangaea's interiors. Precipitation along the western margins of the Palaeo-Tethys Ocean was very high. Evidence for the megamonsoon includes the presence of megamonsoonal rainforests in the Qiangtang Basin of Tibet, enormous seasonal variation in sedimentation, bioturbation, and ichnofossil deposition recorded in sedimentary facies in

11400-530: The next lower trophic level. Food chains can be diagrammed to illustrate the amount of energy that moves from one feeding level to the next in a food chain. This is called an energy pyramid . The energy transferred between levels can also be thought of as approximating to a transfer in biomass , so energy pyramids can also be viewed as biomass pyramids, picturing the amount of biomass that results at higher levels from biomass consumed at lower levels. However, when primary producers grow rapidly and are consumed rapidly,

11514-658: The one-million-year-long set of eruptions that created the majority of the basaltic layers. The traps are divided into sections based on their chemical, stratigraphical, and petrographical composition. The Siberian traps are underlain by the Tungus Syneclise , a large sedimentary basin containing thick sequences of Early-Mid Paleozoic aged carbonate and evaporite deposits, as well as Carboniferous-Permian aged coal bearing clastic rocks . When heated, such as by igneous intrusions , these rocks are capable of emitting large amounts of toxic and greenhouse gases. One of

11628-424: The organism is along the food chain. In real-world ecosystems , there is more than one food chain for most organisms, since most organisms eat more than one kind of food or are eaten by more than one type of predator. A diagram that sets out the intricate network of intersecting and overlapping food chains for an ecosystem is called its food web . Decomposers are often left off food webs, but if included, they mark

11742-481: The preferred catch. They consider that this is part of the global fishery collapse, which finds an echo in the overfished Mediterranean Sea. Humans have a mean trophic level of about 2.21, about the same as a pig or an anchovy. Since biomass transfer efficiencies are only about 10%, it follows that the rate of biological production is much greater at lower trophic levels than it is at higher levels. Fisheries catch, at least, to begin with, will tend to increase as

11856-439: 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 lycopod trees of the Carboniferous, such as Lepidodendron and Sigillaria , were progressively replaced in

11970-587: The same area hundreds of years prior, and which is now located in the Perm Krai administrative region. Between 1853 and 1867, Jules Marcou recognised Permian strata in a large area of North America from the Mississippi River to the Colorado River and proposed the name Dyassic , from Dyas and Trias , though Murchison rejected this in 1871. The Permian system was controversial for over

12084-408: The southeastern South China. 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 , but became heavily eroded as the Permian progressed. The Kazakhstania block collided with Baltica during the Cisuralian, while

12198-532: The spread of conifers and their increasing prevalence throughout terrestrial ecosystems. Bennettitales , which would go on to become in widespread the Mesozoic, first appeared during the Cisuralian in China. 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. The Permian ended with

12312-603: The third land-based again. Trophic level The trophic level of an organism is the position it occupies in a food web . Within a food web, a food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along

12426-522: The time was dominated by the supercontinent Pangaea , which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa . The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. Various authors recognise at least three, and possibly four extinction events in

12540-413: The toxic gas. 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 frozen methane reservoirs below the ocean floor near coastlines melted, expelling enough methane (among

12654-520: The trophic level declines. At this point the fisheries will target species lower in the food web. In 2000, this led Pauly and others to construct a "Fisheries in Balance" index, usually called the FiB index. The FiB index is defined, for any year y , by where Y y {\displaystyle Y_{y}} is the catch at year y , T L y {\displaystyle TL_{y}}

12768-445: The trophic level, TL, for any consumer species is: where T L j {\displaystyle TL_{j}} is the fractional trophic level of the prey j , and D C i j {\displaystyle DC_{ij}} represents the fraction of j in the diet of i . That is, the consumer trophic level is one plus the weighted average of how much different trophic levels contribute to its food. In

12882-525: The volcanism in the Siberian Traps that resulted in high amounts of magmatic material with the Permian–Triassic mass extinction. To further the connection with the Permian–Triassic extinction event, other disastrous events occurred around the same time period, such as sea level changes, meteor impacts and volcanism. Specifically focusing on volcanism, rock samples from the Siberian Traps and other southern regions were obtained and compared. Basalts and gabbro samples from several southern regions close to and from

12996-667: 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 nankingensis . The Wordian was named in reference to

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