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Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
,
Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
and Siberia during the
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic. In contrast to the present Earth and its distribution of continental mass, Pangaea was centred on the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
and surrounded by the
superocean A superocean is an ocean that surrounds a supercontinent. It is less commonly defined as any ocean larger than the current Pacific Ocean. Named global superoceans include Mirovia, which surrounded the supercontinent Rodinia, and Panthalassa, ...
Panthalassa and the
Paleo-Tethys The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; ex ...
and subsequent Tethys Oceans. Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists.


Origin of the concept

The name "Pangaea" is derived from Ancient Greek ''pan'' (, "all, entire, whole") and ''
Gaia In Greek mythology, Gaia (; from Ancient Greek , a poetical form of , 'land' or 'earth'),, , . also spelled Gaea , is the personification of the Earth and one of the Greek primordial deities. Gaia is the ancestral mother—sometimes parthenog ...
'' or Gaea (, "
Mother Earth Mother Earth may refer to: *The Earth goddess in any of the world's mythologies *Mother goddess *Mother Nature, a common personification of the Earth and its biosphere as the giver and sustainer of life Written media and literature *Mother Earth ...
, land"). The concept that the continents once formed a contiguous land mass was hypothesised, with corroborating evidence, by Alfred Wegener, the originator of the
scientific theory A scientific theory is an explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluatio ...
of continental drift, in his 1912 publication ''The Origin of Continents'' (''Die Entstehung der Kontinente'').Alfred Wegener: ''Die Entstehung der Kontinente.'' Dr. A. Petermann's Mitteilungen aus Justus Perthes' Geographischer Anstalt, 58(1): Gotha 1912 He expanded upon his hypothesis in his 1915 book ''The Origin of Continents and Oceans'' (''Die Entstehung der Kontinente und Ozeane''), in which he postulated that, before breaking up and drifting to their present locations, all the continents had formed a single supercontinent that he called the "''Urkontinent''". The name "Pangaea" occurs in the 1920 edition of ''Die Entstehung der Kontinente und Ozeane'', but only once, when Wegener refers to the ancient supercontinent as "the Pangaea of the Carboniferous". Wegener used the Germanized form "Pangäa," but the name entered German and English scientific literature (in 1922 and 1926, respectively) in the Latinized form "Pangaea" (of the Greek "Pangaia"), especially due to a symposium of the
American Association of Petroleum Geologists The American Association of Petroleum Geologists (AAPG) is one of the world's largest professional geological societies with more than 40,000 members across 129 countries as of 2021. The AAPG works to "advance the science of geology, especially as ...
in November 1926.Willem A. J. M. van Waterschoot van der Gracht (and 13 other authors): ''Theory of Continental Drift: a Symposium of the Origin and Movements of Land-masses of both Inter-Continental and Intra-Continental, as proposed by Alfred Wegener.'' X + 240 S., Tulsa, Oklahoma, United States, The American Association of Petroleum Geologists & London, Thomas Murby & Co. Wegener originally proposed that the breakup of Pangaea was due to
centripetal forces A centripetal force (from Latin ''centrum'', "center" and ''petere'', "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous ce ...
from the Earth's rotation acting on the high continents. However, this mechanism was easily shown to be physically implausible, which delayed acceptance of the Pangaea hypothesis.
Arthur Holmes Arthur Holmes (14 January 1890 – 20 September 1965) was an English geologist who made two major contributions to the understanding of geology. He pioneered the use of radiometric dating of minerals, and was the first earth scientist to grasp ...
proposed the more plausible mechanism of
mantle convection Mantle convection is the very slow creeping motion of Earth's solid silicate mantle as convection currents carrying heat from the interior to the planet's surface. The Earth's surface lithosphere rides atop the asthenosphere and the two form ...
, which, together with evidence provided by the mapping of the ocean floor following the Second World War, led to the development and acceptance of the theory of plate tectonics. This theory provides the now widely-accepted explanation for the existence and breakup of Pangaea.


Evidence of existence

The geography of the continents bordering the Atlantic Ocean was the first evidence suggesting the existence of Pangaea. The seemingly close fit of the coastlines of North and South America with Europe and Africa was remarked on almost as soon as these coasts were charted. The first to suggest that these continents were once joined and later separated may have been
Abraham Ortelius Abraham Ortelius (; also Ortels, Orthellius, Wortels; 4 or 14 April 152728 June 1598) was a Brabantian cartographer, geographer, and cosmographer, conventionally recognized as the creator of the first modern atlas, the ''Theatrum Orbis Terraru ...
in 1596. Careful reconstructions showed that the mismatch at the contour was less than , and it was argued that this was much too good to be attributed to chance. Additional evidence for Pangaea is found in the geology of adjacent continents, including matching geological trends between the eastern coast of South America and the western coast of Africa. The
polar ice cap A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor a ...
of the
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
Period covered the southern end of Pangaea. Glacial deposits, specifically till, of the same age and structure are found on many separate continents that would have been together in the continent of Pangaea. The continuity of mountain chains provides further evidence, such as the Appalachian Mountains chain extending from the southeastern United States to the Caledonides of Ireland, Britain, Greenland, and Scandinavia.Merali, Zeeya and Skinner, Brian J. (2009) ''Visualizing Earth Science'', Wiley, Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart. For example, fossils of the therapsid ''
Lystrosaurus ''Lystrosaurus'' (; 'shovel lizard'; proper Greek is λίστρον ''lístron'' ‘tool for leveling or smoothing, shovel, spade, hoe’) is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs (a ...
'' have been found in South Africa, India and Antarctica, alongside members of the '' Glossopteris'' flora, whose distribution would have ranged from the polar circle to the equator if the continents had been in their present position; similarly, the freshwater reptile '' Mesosaurus'' has been found in only localized regions of the coasts of Brazil and West Africa. Geologists can also determine the movement of continental plates by examining the orientation of magnetic minerals in rocks. When rocks are formed, they take on the magnetic orientation of the Earth, showing which direction the poles lie relative to the rock; this determines latitudes and orientations (though not longitudes). Magnetic differences between samples of sedimentary and intrusive igneous rock whose age varies by millions of years is due to a combination of magnetic polar wander (with a cycle of a few thousand years) and the drifting of continents over millions of years. One can subtract the polar wander component, which is identical for all contemporaneous samples, leaving the portion that shows continental drift and can be used to help reconstruct earlier continental latitudes and orientations.


Formation

Pangaea is only the most recent supercontinent reconstructed from the geologic record. The formation of supercontinents and their breakup appears to have been
cyclical Cycle, cycles, or cyclic may refer to: Anthropology and social sciences * Cyclic history, a theory of history * Cyclical theory, a theory of American political history associated with Arthur Schlesinger, Sr. * Social cycle, various cycles in soc ...
through Earth's history. There may have been several others before Pangaea. Paleomagnetic measurements help geologists determine the latitude and orientation of ancient continental blocks, and newer techniques may help determine longitudes. Paleontology helps determine ancient climates, confirming latitude estimates from paleomagnetic measurements, and the distribution of ancient forms of life provides clues on which continental blocks were close to each other at particular geological moments. However, reconstructions of continents prior to Pangaea, including the ones in this section, remain partially speculative, and different reconstructions will differ in some details.


Previous supercontinents

The fourth-last supercontinent, called
Columbia Columbia may refer to: * Columbia (personification), the historical female national personification of the United States, and a poetic name for America Places North America Natural features * Columbia Plateau, a geologic and geographic region in ...
or Nuna, appears to have assembled in the period 2.0–1.8 billion years ago (Ga). Columbia/Nuna broke up and the next supercontinent,
Rodinia Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago. were probably ...
, formed from the
accretion Accretion may refer to: Science * Accretion (astrophysics), the formation of planets and other bodies by collection of material through gravity * Accretion (meteorology), the process by which water vapor in clouds forms water droplets around nucl ...
and assembly of its fragments. Rodinia lasted from about 1.3 billion years ago until about 750 million years ago, but its exact configuration and geodynamic history are not nearly as well understood as those of the later supercontinents,
Pannotia Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent ...
and Pangaea. According to one reconstruction, when Rodinia broke up, it split into three pieces: the supercontinent of
Proto-Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...
, the supercontinent of
Proto-Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
, and the smaller Congo craton. Proto-Laurasia and Proto-Gondwana were separated by the
Proto-Tethys Ocean The Proto-Tethys or Theic Ocean was an ancient ocean that existed from the latest Ediacaran to the Carboniferous (550–330 Ma). History of concept The name "Proto-Tethys" has been used inconsistently for several concepts for a supposed predecess ...
. Next
Proto-Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...
itself split apart to form the continents of Laurentia, Siberia, and Baltica. Baltica moved to the east of Laurentia, and Siberia moved northeast of Laurentia. The splitting also created two new oceans, the
Iapetus Ocean The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoco ...
and Paleoasian Ocean. Most of the above masses coalesced again to form the relatively short-lived supercontinent of
Pannotia Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent ...
. This supercontinent included large amounts of land near the poles and, near the equator, only a relatively small strip connecting the polar masses. Pannotia lasted until 540  Ma, near the beginning of the
Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
period and then broke up, giving rise to the continents of Laurentia, Baltica, and the southern supercontinent of
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
.


Formation of Euramerica (Laurussia)

In the
Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
period, the continent of Laurentia, which would later become
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, sat on the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
, with three bordering oceans: the
Panthalassic Ocean Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the ...
to the north and west, the
Iapetus Ocean The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoco ...
to the south, and the
Khanty Ocean Khanty or Khanty-Mansi Ocean was a small ocean located between Baltica and an island arc (the Kipchaks, Kipchak Arc) near Siberia (continent), Siberia, from near the end of the Precambrian time to the Silurian. The ocean is named after two indige ...
to the east. In the Earliest Ordovician, around 480 Ma, the microcontinent of
Avalonia Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of Wester ...
– a landmass incorporating fragments of what would become eastern
Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
, the southern British Isles, and parts of Belgium, northern France, Nova Scotia, New England, South Iberia, and northwest Africa – broke free from Gondwana and began its journey to Laurentia. Baltica, Laurentia, and Avalonia all came together by the end of the Ordovician to form a landmass called
Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
or Laurussia, closing the Iapetus Ocean. The collision also resulted in the formation of the northern Appalachians. Siberia sat near Euramerica, with the
Khanty Ocean Khanty or Khanty-Mansi Ocean was a small ocean located between Baltica and an island arc (the Kipchaks, Kipchak Arc) near Siberia (continent), Siberia, from near the end of the Precambrian time to the Silurian. The ocean is named after two indige ...
between the two continents. While all this was happening, Gondwana drifted slowly towards the South Pole. This was the first step of the formation of Pangaea.


Collision of Gondwana with Euramerica

The second step in the formation of Pangaea was the collision of Gondwana with Euramerica. By the middle of the
Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
, 430 Ma, Baltica had already collided with Laurentia, forming Euramerica, an event called the Caledonian orogeny.
Avalonia Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of Wester ...
had not yet collided with Laurentia, but as Avalonia inched towards Laurentia, the seaway between them, a remnant of the
Iapetus Ocean The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoco ...
, was slowly shrinking. Meanwhile, southern Europe broke off from Gondwana and began to move towards Euramerica across the Rheic Ocean. It collided with southern Baltica in the
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
. By the late Silurian, Annamia and
South China South China () is a geographical and cultural region that covers the southernmost part of China. Its precise meaning varies with context. A notable feature of South China in comparison to the rest of China is that most of its citizens are not n ...
split from Gondwana and started to head northward, shrinking the Proto-Tethys Ocean in their path and opening the new Paleo-Tethys Ocean to their south. In the Devonian Period, Gondwana itself headed towards Euramerica, causing the Rheic Ocean to shrink. In the Early
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
, northwest Africa had touched the southeastern coast of
Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
, creating the southern portion of the Appalachian Mountains, the
Meseta Mountains The Moroccan Meseta or Western Meseta, are uplifted terranes of dominantly Palaeozoic rocks exposed along the Moroccan coastal block between the Atlantic Margin and the Middle Atlas. Geology The Meseta Domain, taking its name from Spain's Mes ...
, and the Mauritanide Mountains, an event called the Variscan orogeny. South America moved northward to southern Euramerica, while the eastern portion of Gondwana ( India, Antarctica, and
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
) headed toward the South Pole from the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
. North and South China were on independent continents. The
Kazakhstania Kazakhstania ( kk, Qazaqstaniya), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia which consists of the area roughly centered on Lake Balkhash, north and east of the Aral Sea, south of the Siberian craton and w ...
microcontinent had collided with Siberia. (Siberia had been a separate continent for millions of years since the deformation of the supercontinent
Pannotia Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent ...
in the Middle Carboniferous.) The Variscan orogeny raised the
Central Pangaean Mountains The Central Pangean Mountains were an extensive northeast–southwest trending mountain range in the central portion of the supercontinent Pangaea during the Carboniferous, Permian and Triassic periods. They were formed as a result of collision ...
, which were comparable to the modern Himalayas in scale. With Pangaea now stretching from the South Pole across the equator and well into the Northern Hemisphere, an intense megamonsoon climate was established, except for a perpetually wet zone immediately around the central mountains.


Formation of Laurasia

Western
Kazakhstania Kazakhstania ( kk, Qazaqstaniya), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia which consists of the area roughly centered on Lake Balkhash, north and east of the Aral Sea, south of the Siberian craton and w ...
collided with Baltica in the Late Carboniferous, closing the Ural Ocean between them and the western Proto-Tethys in them ( Uralian orogeny), causing the formation of not only the Ural Mountains, but also the supercontinent of Laurasia. This was the last step of the formation of Pangaea. Meanwhile, South America had collided with southern Laurentia, closing the Rheic Ocean and completing the Variscian orogeny with the formation the southernmost part of the Appalachians and Ouachita Mountains. By this time, Gondwana was positioned near the South Pole, and glaciers were forming in Antarctica, India, Australia, southern Africa, and South America. The
North China North China, or Huabei () is a List of regions of China, geographical region of China, consisting of the provinces of Beijing, Tianjin, Hebei, Shanxi and Inner Mongolia. Part of the larger region of Northern China (''Beifang''), it lies north ...
block collided with Siberia by Jurassic, completely closing the Proto-Tethys Ocean. By the
Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...
, the Cimmerian plate split from
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
and headed towards Laurasia, thus closing the Paleo-Tethys Ocean, but forming a new ocean, the Tethys Ocean, in its southern end. Most of the landmasses were all in one. By the Triassic Period, Pangaea rotated a little, and the Cimmerian plate was still travelling across the shrinking Paleo-Tethys until the
Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
. By the late Triassic, the Paleo-Tethys had closed from west to east, creating the Cimmerian Orogeny. Pangaea, which looked like a ''C'', with the new Tethys Ocean inside the ''C'', had rifted by the Middle Jurassic, and its deformation is explained below.


Life

Pangaea existed as a supercontinent for 160 million years, from its assembly around 335 million years ago ( Early Carboniferous) to its breakup 175 million years ago (
Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
). During this interval, important developments in the evolution of life took place. The seas of the Early Carboniferous were dominated by
rugose corals The rugosa, also called the tetracorallia or horn coral, are an extinct order of solitary and colonial corals that were abundant in Middle Ordovician to Late Permian seas. Solitary rugosans (e.g., '' Caninia'', '' Lophophyllidium'', '' Neoza ...
, brachiopods, bryozoans, sharks, and the first
bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...
. Life on land was dominated by lycopsid forests inhabited by insects and other arthropods and the first tetrapods. By the time Pangaea broke up, in the Middle Jurassic, the seas swarmed with
mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is esti ...
s (particularly
ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
s),
ichthyosaur Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
s, sharks and rays, and the first ray-finned bony fishes, while life on land was dominated by forests of cycads and
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
s in which dinosaurs flourished and in which the first true
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s had appeared. The evolution of life in this time reflected the conditions created by the assembly of Pangaea. The union of most of the continental crust into one landmass reduced the extent of sea coasts. Increased erosion from uplifted continental crust increased the importance of floodplain and delta environments relative to shallow marine environments. Continental assembly and uplift also meant increasingly arid land climates, favoring the evolution of
amniote Amniotes are a clade of tetrapod vertebrates that comprises sauropsids (including all reptiles and birds, and extinct parareptiles and non-avian dinosaurs) and synapsids (including pelycosaurs and therapsids such as mammals). They are disti ...
animals and seed plants, whose eggs and seeds were better adapted to dry climates. The early drying trend was most pronounced in western Pangaea, which became a center of the evolution and geographical spread of amniotes. Coal swamps typically form in perpetually wet regions close to the equator. The assembly of Pangaea disrupted the
intertropical convergence zone The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal e ...
and created an extreme monsoon climate that reduced the deposition of coal to its lowest level in the last 300 million years. During the Permian, coal deposition was largely restricted to the North and South China microcontinents, which were among the few areas of continental crust that had not joined with Pangaea. The extremes of climate in the interior of Pangaea are reflected in bone growth patterns of
pareiasaur Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with scutes which covered large areas of the body. They first appeared in southern Pangea during the Middle Permian, ...
s and the growth patterns in gymnosperm forests. The lack of oceanic barriers is thought to have favored ''cosmopolitanism'', in which successful species attain wide geographical distribution. Cosmopolitanism was also driven by mass extinctions, including the Permian–Triassic extinction event, the most severe in the fossil record, and also the Triassic–Jurassic extinction event. These events resulted in ''disaster fauna'' showing little diversity and high cosmopolitanism, including ''
Lystrosaurus ''Lystrosaurus'' (; 'shovel lizard'; proper Greek is λίστρον ''lístron'' ‘tool for leveling or smoothing, shovel, spade, hoe’) is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs (a ...
'', which opportunistically spread to every corner of Pangaea following the Permian–Triassic extinction event. On the other hand, there is evidence that many Pangaean species were ''provincial'', with a limited geographical range, despite the absence of geographical barriers. This may be due to the strong variations in climate by latitude and season produced by the extreme monsoon climate. For example, cold-adapted
pteridosperm The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a polyphyletic group of extinct seed-bearing plants (spermatophytes). The earliest fossil evidence for plants of this type is the genus ''Elkinsia'' of the late Devonian ...
s (early seed plants) of Gondwana were blocked from spreading throughout Pangaea by the equatorial climate, and northern pteridosperms ended up dominating Gondwana in the Triassic.


Mass extinctions

The tectonics and geography of Pangaea may have worsened the Permian–Triassic extinction event or other extinctions. For example, the reduced area of continental shelf environments may have left marine species vulnerable to extinction. However, no evidence for a species-area effect has been found in more recent and better characterized portions of the geologic record. Another possibility is that reduced sea-floor spreading associated with the formation of Pangaea, and the resulting cooling and subsidence of oceanic crust, may have reduced the number of islands that could have served as refugia for marine species. Species diversity may have already been reduced prior to mass extinction events due to mingling of species possible when formerly separate continents were merged. However, there is strong evidence that climate barriers continued to separate ecological communities in different parts of Pangaea. The eruptions of the
Emeishan Traps The Emeishan Traps constitute a flood basalt volcanic province, or large igneous province, in south-western China, centred in Sichuan province. It is sometimes referred to as the Permian Emeishan Large Igneous Province or Emeishan Flood Basalts. Li ...
may have eliminated South China, one of the few continental areas not merged with Pangaea, as a refugium.


Rifting and break-up

There were three major phases in the break-up of Pangaea.


Opening of the Atlantic

The Atlantic Ocean did not open uniformly; rifting began in the north-central Atlantic. The first breakup of Pangaea is proposed for the late Ladinian (230 Ma) with initial spreading in the opening central Atlantic. Then the rifting proceeded along the eastern margin of North America, the northwest African margin and the High, Saharan and Tunisian Atlas. Another phase began in the
Early Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...
-
Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
(about 175 Ma), when Pangaea began to rift from the Tethys Ocean in the east to the Pacific Ocean in the west. The rifting that took place between North America and Africa produced multiple failed rifts. One rift resulted in a new ocean, the North Atlantic Ocean. The South Atlantic did not open until the Cretaceous when Laurasia started to rotate clockwise and moved northward with North America to the north, and Eurasia to the south. The clockwise motion of Laurasia led much later to the closing of the Tethys Ocean and the widening of the "Sinus Borealis", which later became the Arctic Ocean. Meanwhile, on the other side of Africa and along the adjacent margins of east Africa, Antarctica and Madagascar, new rifts were forming that would lead to the formation of the southwestern Indian Ocean that would open up in the Cretaceous.


Break-up of Gondwana

The second major phase in the break-up of Pangaea began in the
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
(150–140 Ma), when the landmass of Gondwana separated into multiple continents (Africa, South America, India, Antarctica, and Australia). The subduction at Tethyan Trench probably caused Africa, India and Australia to move northward, causing the opening of a "South Indian Ocean". In the Early Cretaceous, Atlantica, today's South America and Africa, finally separated from eastern Gondwana (Antarctica, India and Australia). Then in the Middle Cretaceous, Gondwana fragmented to open up the South Atlantic Ocean as South America started to move westward away from Africa. The South Atlantic did not develop uniformly; rather, it rifted from south to north. Also, at the same time, Madagascar and India began to separate from Antarctica and moved northward, opening up the Indian Ocean. Madagascar and India separated from each other 100–90 Ma in the Late Cretaceous. India continued to move northward toward Eurasia at 15 centimeters (6 in) a year (a plate tectonic record), closing the eastern Tethys Ocean, while Madagascar stopped and became locked to the African Plate. New Zealand,
New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...
and the rest of Zealandia began to separate from Australia, moving eastward toward the Pacific and opening the
Coral Sea The Coral Sea () is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion. The Coral Sea extends down the Australian northeast coast. Most of it is protected by the Fre ...
and Tasman Sea.


Opening of the Norwegian Sea and break-up of Australia and Antarctica

The third major and final phase of the break-up of Pangaea occurred in the early
Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
( Paleocene to
Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
).
Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
split when North America/Greenland (also called Laurentia) broke free from Eurasia, opening the Norwegian Sea about 60–55 Ma. The Atlantic and Indian Oceans continued to expand, closing the Tethys Ocean. Meanwhile, Australia split from Antarctica and moved quickly northward, just as India had done more than 40 million years before. Australia is currently on a collision course with
eastern Asia East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...
. Both Australia and India are currently moving northeast at 5–6 centimeters (2–3 in) a year. Antarctica has been near or at the South Pole since the formation of Pangaea about 280 Ma. India started to collide with Asia beginning about 35 Ma, forming the Himalayan orogeny, and also finally closing the
Tethys Seaway The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...
; this collision continues today. The African Plate started to change directions, from west to northwest toward Europe, and South America began to move in a northward direction, separating it from Antarctica and allowing complete oceanic circulation around Antarctica for the first time. This motion, together with decreasing atmospheric carbon dioxide concentrations, caused a rapid cooling of Antarctica and allowed glaciers to form. This glaciation eventually coalesced into the kilometers-thick ice sheets seen today. Other major events took place during the
Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
, including the opening of the Gulf of California, the uplift of the Alps, and the opening of the Sea of Japan. The break-up of Pangaea continues today in the Red Sea Rift and
East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. In the past it was considered to be part of a ...
.


Climate change after Pangaea

The breakup of Pangaea was accompanied by outgassing of large quantities of carbon dioxide from continental rifts. This produced a Mesozoic CO2 High that contributed to the very warm climate of the
Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145  Ma to 100.5 Ma. Geology Pro ...
. The opening of the Tethys Ocean also contributed to the warming of the climate. The very active mid-ocean ridges associated with the breakup of Pangaea raised sea levels to the highest in the geological record, flooding much of the continents. The expansion of the temperate climate zones that accompanied the breakup of Pangaea may have contributed to the diversification of the
angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s.


See also

*
History of Earth The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologi ...
* Potential future supercontinents:
Pangaea Ultima Pangaea Proxima (also called Pangaea Ultima, Neopangaea, and Pangaea II) is a possible future supercontinent configuration. Consistent with the supercontinent cycle, Pangaea Proxima could occur within the next 200 million years. This potential c ...
,
Novopangaea Novopangaea or Novopangea (Greco-Latin for "New Pangaea") is a possible future supercontinent postulated by Roy Livermore in the late 1990s. It assumes closure of the Pacific,Wilkins, Alasdair.A Geological History of Supercontinents on Planet Eart ...
&
Amasia Amasia may refer to the following places: * Amasya, a city in Northern Turkey ** Amasya Province, which contains the city ** Amasea (titular see), the former Metropolitan Archbishopric with see there, now a Latin Catholic titular see * Amasia, Shir ...
* Supercontinent cycle *
Wilson Cycle The Wilson Cycle is a model that describes the opening and closing of ocean basins and the subduction and divergence of tectonic plates during the assembly and disassembly of supercontinents. A classic example of the Wilson Cycle is the opening an ...


References


External links


USGS Overview




{{Authority control Carboniferous paleogeography Former supercontinents Historical continents Jurassic paleogeography Permian paleogeography Plate tectonics Triassic paleogeography