Permian

Last updated
Permian Period
298.9–251.902 million years ago
Є
O
S
D
C
P
T
J
K
Pg
N
Mean atmospheric O
2
content over period duration
c. 23 vol %
(115 % of modern level)
Mean atmospheric CO
2
content over period duration
c. 900 ppm
(3 times pre-industrial level)
Mean surface temperature over period durationc. 16 °C
(2 °C above modern level)
Sea level (above present day)Relatively constant at 60 m (200 ft) in early Permian; plummeting during the middle Permian to a constant −20 m (−66 ft) in the late Permian. [1]
Key events in the Permian
-300 
-295 
-290 
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-270 
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-255 
-250 
An approximate timescale of key Permian events.
Axis scale: millions of years ago.

The Permian is a geologic period and 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 is the 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 city of Perm.

A system in stratigraphy is a unit of rock layers that were laid down together within the same corresponding geological period. The associated period is a chronological time unit, a part of the geological time scale, while the system is a unit of chronostratigraphy. Systems are unrelated to lithostratigraphy, which subdivides rock layers on their lithology. Systems are subdivisions of erathems and are themselves divided into series and stages.

The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means "coal-bearing" and derives from the Latin words carbō ("coal") and ferō, and was coined by geologists William Conybeare and William Phillips in 1822.

The Triassic is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.9 million years ago (Mya), to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events.

Contents

The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs, and archosaurs. The world at the time was dominated by two continents known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. [2] Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors.

Amniote group of tetrapods

Amniotes are a clade of tetrapod vertebrates comprising the reptiles, birds, and mammals. Amniotes lay their eggs on land or retain the fertilized egg within the mother, and are distinguished from the anamniotes, which typically lay their eggs in water. Older sources, particularly prior to the 20th century, may refer to amniotes as "higher vertebrates" and anamniotes as "lower vertebrates", based on the discredited idea of the evolutionary great chain of being.

Mammal class of tetrapods

Mammals are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals. The largest orders are the rodents, bats and Soricomorpha. The next three are the Primates, the Cetartiodactyla, and the Carnivora.

Turtle order of reptiles

Turtles are diapsids of the order Testudines characterized by a special bony or cartilaginous shell developed from their ribs and acting as a shield. "Turtle" may refer to the order as a whole or to fresh-water and sea-dwelling testudines. The order Testudines includes both extant (living) and extinct species. The earliest known members of this group date from 220 million years ago, making turtles one of the oldest reptile groups and a more ancient group than snakes or crocodilians. Of the 356 known species alive today, some are highly endangered.

The Permian (along with the Paleozoic) ended with the Permian–Triassic extinction event, the largest mass extinction in Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out. [3] It would take well into the Triassic for life to recover from this catastrophe. [4] Recovery from the Permian–Triassic extinction event was protracted; on land, ecosystems took 30 million years to recover. [5]

Permian–Triassic extinction event most severe extinction event of Earths chronology, occurring approx 252 million years ago, ending the Paleozoic era (and the Permian period) and beginning the Mesozoic era (and the Triassic period)

The Permian–Triassicextinction event, colloquially known as the Great Dying, the End-Permian Extinction or the Great Permian Extinction, occurred about 252 Ma ago, forming the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It was the largest known mass extinction of insects. Some 57% of all biological families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of land-dwelling life took significantly longer than after any other extinction event, possibly up to 10 million years. Studies in Bear Lake County, near Paris, Idaho, showed a relatively quick rebound in a localized marine ecosystem, taking around 2 million years to recover, suggesting that the impact of the extinction may have been felt less severely in some areas than others.

Discovery

The term "Permian" was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Édouard de Verneuil. [6] [7] The region now lies in the Perm Krai of Russia.

Geology The study of the composition, structure, physical properties, and history of Earths components, and the processes by which they are shaped.

Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology significantly overlaps all other earth sciences, including hydrology and the atmospheric sciences, and so is treated as one major aspect of integrated earth system science and planetary science.

Roderick Murchison geologist

Sir Roderick Impey Murchison, 1st Baronet, was a Scottish geologist who first described and investigated the Silurian system.

Geological Society of London learned society

The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows. Fellows are entitled to the postnominal FGS, over 2,000 of whom are Chartered Geologists (CGeol). The Society is a Registered Charity, No. 210161. It is also a member of the Science Council, and is licensed to award Chartered Scientist to qualifying members.

ICS subdivisions

Official ICS 2017 subdivisions of the Permian System from most recent to most ancient rock layers are: [8]

Lopingian epoch [259.8 ± 0.4 Mya – 251.902 ± 0.06 Mya]
  • Changhsingian (Changxingian) [254.1 ± 0.07 Mya – 251.902 ± 0.06 Mya]
  • Wuchiapingian (Wujiapingian) [259.8 ± 0.4 Mya – 254.1 ± 0.07 Mya]
  • Others:
    • Waiitian (New Zealand) [260.4 ± 0.7 Mya – 253.8 ± 0.7 Mya]
    • Makabewan (New Zealand) [253.8 – 251.0 ± 0.4 Mya]
    • Ochoan (North American) [260.4 ± 0.7 Mya – 251.0 ± 0.4 Mya]

In the geologic time scale, the Changhsingian or Changxingian is the latest age or uppermost stage of the Permian. It is also the upper or latest of two subdivisions of the Lopingian epoch or series. The Changhsingian lasted from 254.14 to 251.902 million years ago (Ma). It was preceded by the Wuchiapingian and followed by the Induan.

In the geologic timescale, the Wuchiapingian or Wujiapingian is an age or stage of the Permian. It is also the lower or earlier of two subdivisions of the Lopingian epoch or series. The Wuchiapingian spans the time between 259.1 and 254.14 million years ago (Ma). It was preceded by the Capitanian and followed by the Changhsingian.

The Ochoan is a stage in the Permian stratigraphy of North America. The Ochoan age is roughly simultaneous with the Changhsingian age in the timescale of the ICS. This post-Guadalupian stage is known for high levels of evaporite deposits.

Guadalupian epoch [272.3 ± 0.5 – 259.8 ± 0.4 Mya]
  • Capitanian stage [265.1 ± 0.4 – 259.8 ± 0.4 Mya]
  • Wordian stage [268.8 ± 0.5 – 265.1 ± 0.4 Mya]
  • Roadian stage [272.3 ± 0.5 – 268.8 ± 0.5 Mya]
  • Others:
    • Kazanian or Maokovian (European) [270.6 ± 0.7 – 260.4 ± 0.7 Mya] [9]
    • Braxtonian stage (New Zealand) [270.6 ± 0.7 – 260.4 ± 0.7 Mya]
Cisuralian epoch [298.9 ± 0.15 – 272.3 ± 0.5 Mya]
  • Kungurian stage [283.5 ± 0.7 – 272.3 ± 0.5 Mya]
  • Artinskian stage [290.1 ± 0.7 – 283.5 ± 0.7 Mya]
  • Sakmarian stage [295. ± 0.8 – 290.1 ± 0.7 Mya]
  • Asselian stage [298.9 ± 0.15 – 294.6 ± 0.8 Mya]
  • Others:
    • Telfordian (New Zealand) [289 – 278]
    • Mangapirian (New Zealand) [278 – 270.6]

Oceans

Sea levels in the Permian remained generally low, and near-shore environments were reduced as almost all major landmasses collected into a single continent—Pangaea. This could have in part caused the widespread extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms.

Paleogeography

Geography of the Permian world 280 Ma plate tectonic reconstruction.png
Geography of the Permian world

During the Permian, all the Earth's major landmasses were collected into a single supercontinent known as Pangaea. 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 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 Tethys Ocean, an ocean that would dominate much of the Mesozoic era. Large continental landmass interiors experience climates with extreme variations of heat and cold ("continental climate") and monsoon conditions with highly seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a protective cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees (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 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.

Climate

Selwyn Rock, South Australia, an exhumed glacial pavement of Permian age Selwyn Rock 2.JPG
Selwyn Rock, South Australia, an exhumed glacial pavement of Permian age

The climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an ice age, which began in the Carboniferous. Glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continent's interiors. [10] In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles. [10]

Life

Hercosestria cribrosa, a reef-forming productid brachiopod (Middle Permian, Glass Mountains, Texas) HercosestriaPair040111.jpg
Hercosestria cribrosa, a reef-forming productid brachiopod (Middle Permian, Glass Mountains, Texas)

Marine biota

Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. [11] Fossilized shells of two kinds of invertebrates are widely used to identify Permian strata and correlate them between sites: fusulinids, a kind of shelled amoeba-like protist that is one of the foraminiferans, and ammonoids, shelled cephalopods that are distant relatives of the modern nautilus. By the close of the Permian, trilobites and a host of other marine groups became extinct.

Terrestrial biota

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. [11] 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 lycopod trees of the Carboniferous, such as Lepidodendron and Sigillaria , were progressively replaced in the continental interior by the more advanced seed ferns and early conifers. At the close of the Permian, lycopod and equisete swamps reminiscent of Carboniferous flora survived only on a series of equatorial islands in the Paleo-Tethys Ocean that later would become South China. [12]

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 ginkgos and cycads also appeared during this period.

Insects

From the Pennsylvanian subperiod of the Carboniferous period until well into the Permian, the most successful insects were primitive relatives of cockroaches. Six fast legs, four well-developed folding wings, fairly good eyes, long, well-developed antennae (olfactory), an omnivorous digestive system, a receptacle for storing sperm, a chitin-based exoskeleton that could support and protect, as well as a form of gizzard and efficient mouth parts, gave it formidable advantages over other herbivorous animals. About 90% of insects at the start of the Permian were cockroach-like insects ("Blattopterans"). [13]

Primitive forms of dragonflies (Odonata) were the dominant aerial predators and probably dominated terrestrial insect predation as well. True Odonata appeared in the Permian, [14] [15] and all are effectively semi-aquatic insects (aquatic immature stages, and terrestrial adults), as are all modern odonates. Their prototypes are the oldest winged fossils, [16] dating back to the Devonian, and are different in several respects from the wings of other insects. [17] Fossils suggest they may have possessed many modern attributes even by the late Carboniferous, and it is possible that they captured small vertebrates, for at least one species had a wing span of 71 cm (28 in). [18] Several other insect groups appeared or flourished during the Permian, including the Coleoptera (beetles) and Hemiptera (true bugs).

Synapsid and amphibian fauna

Early Permian terrestrial faunas were dominated by pelycosaurs, diadectids and amphibians, [19] [20] the middle Permian by primitive therapsids such as the dinocephalia, and the late Permian by more advanced therapsids such as gorgonopsians and dicynodonts. Towards the very end of the Permian the first archosaurs appeared, a group that would give rise to the crurotarsans and the dinosaurs in the following period. Also appearing at the end of the Permian were the first cynodonts, which would go on to evolve into mammals during the Triassic. Another group of therapsids, the therocephalians (such as Lycosuchus ), arose in the Middle Permian. [21] [22] There were no aerial vertebrates (with the exception of gliding reptiles, the avicephalans).

The Permian period saw the development of a fully terrestrial fauna and the appearance of the first large herbivores and carnivores. It was the high tide of the anapsids in the form of the massive Pareiasaurs and host of smaller, generally lizard-like groups. A group of small reptiles, the diapsids, started to abound. These were the ancestors to most modern reptiles and the ruling dinosaurs as well as pterosaurs and crocodiles.

The synapsid, early ancestors to mammals, also thrived at this time. Synapsids included some large members such as Dimetrodon . The special adaptations of reptiles enabled them to flourish in the drier climate of the Permian and they grew to dominate the vertebrates. [19]

Permian amphibians consisted of temnospondyli, lepospondyli and batrachosaurs.

Permian–Triassic extinction event

The Permian-Triassic extinction event, labeled "End P" here, is the most significant extinction event in this plot for marine genera which produce large numbers of fossils Extinction Intensity.svg
The Permian–Triassic extinction event, labeled "End P" here, is the most significant extinction event in this plot for marine genera which produce large numbers of fossils

The Permian ended with the most extensive extinction event recorded in paleontology: the Permian–Triassic extinction event. Ninety 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. [4] [23] Recovery from the Permian–Triassic extinction event was protracted; on land, ecosystems took 30 million years to recover. [5] Trilobites, which had thrived since Cambrian times, finally became extinct before the end of the Permian. Nautiluses, a species of cephalopods, surprisingly survived this occurrence.

There is evidence that magma, in the form of flood basalt, poured onto the 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 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. [10]

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, 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. [24] 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 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. [25]

An even more speculative hypothesis is that intense radiation from a nearby supernova was responsible for the extinctions. [26]

It has been hypothesised that huge meteorite impact crater (Wilkes Land crater) with a diameter of around 500 kilometers in Antarctica represents an impact event that may be related to the extinction. [27] The crater is located at a depth of 1.6 kilometers beneath the ice of Wilkes Land in eastern Antarctica. The scientists speculate that this impact may have caused the Permian–Triassic extinction event, although its age is bracketed only between 100 million and 500 million years ago. They also speculate that it may have contributed in some way to the separation of Australia from the Antarctic landmass, which were both part of a supercontinent called Gondwana. Levels of iridium and quartz fracturing in the Permian–Triassic layer do not approach those of the Cretaceous–Paleogene boundary layer. Given that a far greater proportion of species and individual organisms became extinct during the former, doubt is cast on the significance of a meteorite impact in creating the latter. Further doubt has been cast on this theory based on fossils in Greenland that show the extinction to have been gradual, lasting about eighty thousand years, with three distinct phases. [28]

Many scientists argue that the Permian–Triassic extinction event was caused by a combination of some or all of the hypotheses above and other factors; the formation of Pangaea decreased the number of coastal habitats and may have contributed to the extinction of many clades.[ citation needed ]

See also

Related Research Articles

The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, England, where rocks from this period were first studied.

Extinction event Widespread and rapid decrease in the biodiversity on Earth

An extinction event is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from the threshold chosen for describing an extinction event as "major", and the data chosen to measure past diversity.

The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. It is also called the Age of Reptiles and the Age of Conifers.

Panthalassa Prehistoric superocean that surrounded Pangaea

Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean, was the superocean that surrounded the supercontinent Pangaea. During the Paleozoic–Mesozoic transition c. 250 Ma it occupied almost 70% of Earth's surface. Its ocean floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific or Proto-Pacific because the Pacific Ocean developed from its centre in the Mesozoic to the present.

The Guadalupian or Middle Permian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and date between 272.3 ± 0.5 – 259.8 ± 0.4 Mya. The series saw the rise of the therapsids and a minor extinction event called Olson’s Extinction.

The Cisuralian or Early Permian is the first series/epoch of the Permian. The Cisuralian was preceded by the Pennsylvanian and followed by the Guadalupian. The Cisuralian Epoch is named after the western slopes of the Ural Mountains in Russia and Kazakhstan and dates between 298.9 ± 0.15 – 272.3 ± 0.5 Mya.

The Late Triassic is the third and final of three epochs of the Triassic Period in the geologic timescale. The Triassic-Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. The corresponding series is known as the Upper Triassic. In Europe the epoch was called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age. The Late Triassic spans the time between 237 Ma and 201.3 Ma. The Late Triassic is divided into the Carnian, Norian and Rhaetian ages.

Therocephalia suborder of mammals (fossil)

Therocephalia is an extinct suborder of eutheriodont therapsids from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. This relationship takes evidence in a variety of skeletal features. The phylogeny of therocephalians has been disputed, as the monophyly of the group and the relationships of its members are unclear.

Procynosuchidae family of mammals (fossil)

Procynosuchidae is an extinct family of therapsids which, along with Dviniidae, were the earliest cynodonts. They appeared around 260 million years ago, and were most abundant during the latest Permian time, shortly before the Permian-Triassic extinction event. Despite being the basal member of the cynodont clade, they already showed some of the advanced mammalian characteristics, but Procynosuchids bore resemblance to the Therocephalians.

Geological history of Earth The sequence of major geological events in Earths past

The geological history of Earth follows the major events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.

Gondwana Neoproterozoic to Carboniferous supercontinent

Gondwana, , was a supercontinent that existed from the Neoproterozoic until the Jurassic.

Pangaea Supercontinent from the late Paleozoic to early Mesozoic eras

Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 million years ago. In contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the southern hemisphere and surrounded by a superocean, Panthalassa. Pangaea was the most recent supercontinent to have existed and the first to be reconstructed by geologists.

<i>Rhineceps</i> Genus of amphibians (fossil)

Rhineceps is an extinct genus of temnospondyl amphibian in the family Rhinesuchidae. Rhineceps was found in Northern Malawi in Southern Africa known only from its type species R. nyasaensis. Rhineceps was a late Permian semi-aquatic carnivore that lived in streams, rivers, lakes or lagoons. Rhineceps is an early divergent Stereopondyl within the family Rhinesuchidae, which only existed in the late Permian (Lopingian) and failed to survive the Permian-Triassic extinction unlike other stereospondyl families.

Promoschorhynchus is a genus of akidnognathid therocephalians from the Late Permian and Early Triassic of South Africa. Unlike many other therapsids, Promoschorhynchus survived the Permian-Triassic extinction event.

A paleocontinent or palaeocontinent is a distinct area of continental crust that existed as a major landmass in the geological past. There have been many different landmasses throughout Earth’s time. They range in sizes, some are just a collection of small microcontinents while others are large conglomerates of crust. As time progresses and sea levels rise and fall more crust can be exposed making way for larger landmasses. The continents of the past shaped the evolution of organisms on Earth and contributed to the climate of the globe as well. As land masses break apart, species are separated and those that were once the same now have evolved to their new climate. The constant movement of these landmasses greatly determines the distribution of organisms on the Earth's surface. This is evident with how similar fossils are found on completely separate continents. Also, as continents move, mountain building events (orogenies) occur, causing a shift in the global climate as new rock is exposed and then there is more exposed rock at higher elevations. This causes glacial ice expansion and an overall cooler global climate. Which effects the overall global climate trend of the Earth. The movement of the continents greatly affects the overall dispersal of organisms throughout the world and the trend in climate throughout the Earth’s history. Examples include Laurentia, Baltica and Avalonia, which collided together during the Caledonian orogeny to form the Old Red Sandstone paleocontinent of Laurussia. Another example includes a collision that occurred during the late Pennsylvanian and early Permian time when there was a collision between the two continents of Tarimsky and Kirghiz-Kazakh. This collision was caused because of their askew convergence when the paleoceanic basin closed.

Olson's Extinction was a mass extinction that occurred 273 million years ago in the early Guadalupian of the Permian period and which predated the Permian–Triassic extinction event. It is named after Everett C. Olson. There was a hiatus and a sudden change in between the early Permian and middle/late Permian faunas. Since then this event has been realized across many groups, including plants, marine invertebrates, and tetrapods.

Carboniferous rainforest collapse extinction event; occurred ca. 305 Ma at the end of the Moscovian in the Carboniferous; altered the vast coal forests that covered the equatorial region of Euramerica, fragmenting them into ‘islands’, causing dwarfism and extinction of many species

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. This event may have fragmented the forests into isolated 'islands', which in turn caused dwarfism and, shortly after, extinction of many plant and animal species. Following the event, coal-forming tropical forests continued in large areas of the Earth, but their extent and composition were changed.

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Further reading