Permian
Sir Roderick Impey Murchison introduced the term Permian into geology in 1841. He named it after the region of Perm in Russia following extensive explorations with Édouard de Verneuil near the Ural Mountains during 1840 and 1841. Murchison identified vast series of marl, schist, limestone, sandstone, and conglomerate that succeeded Carboniferous strata in that area. The name derived from the medieval kingdom of Permia which occupied the same territory hundreds of years prior. Before this introduction, rocks of equivalent age in Germany were called Rotliegend and Zechstein while Great Britain used New Red Sandstone. Between 1853 and 1867 Jules Marcou recognized Permian strata across North America from the Mississippi River to the Colorado River. He proposed the name Dyassic from Dyas and Trias but Murchison rejected this proposal in 1871. The system remained controversial for over a century until the United States Geological Survey finally accepted it as distinct from the Carboniferous in 1941.
The Cisuralian Series takes its name from strata exposed on the western slopes of the Ural Mountains in Russia and Kazakhstan. J.B. Waterhouse proposed this name in 1982 to include the Asselian, Sakmarian, and Artinskian stages. Albert Auguste Cochon de Lapparent had earlier suggested the Uralian Series in 1900 before inconsistent usage led to its abandonment. The Asselian stage was named by Russian stratigrapher V.E. Ruzhenchev in 1954 after the Assel River in the southern Ural Mountains. Its Global Boundary Stratotype Section and Point sits in the Aidaralash River valley near Aqtöbe, Kazakhstan, ratified in 1996. The boundary marks the first appearance of Streptognathodus postfusus. Alexander Karpinsky coined the Sakmarian in 1874 referencing the Sakmara River in the southern Urals. This stage's GSSP lies at the Usolka section in the southern Urals, ratified in 2018. It begins with the first appearance of Sweetognathus binodosus. The Artinskian derives its name from the city of Arti in Sverdlovsk Oblast, Russia, also named by Karpinsky in 1874. No defined GSSP exists for the Artinskian yet. Recent proposals suggest Neostreptognathodus pnevi as a lower boundary marker.
During the Permian all Earth's major landmasses collected into a single supercontinent known as Pangaea. Microcontinental terranes like Cathaysia sat to the east while Pangaea straddled the equator extending toward the poles. Ocean currents flowed through Panthalassa, the universal sea, and the Paleo-Tethys Ocean between Asia and Gondwana. The Cimmeria continent rifted away from Gondwana drifting north to Laurasia causing the Paleo-Tethys Ocean to shrink. A new ocean called the Neotethys grew on its southern end dominating much of the Mesozoic Era. Magmatic arcs containing Hainan began forming as Panthalassa subducted under southeastern South China. The Central Pangean Mountains reached maximum height during the early Permian around 295 Ma comparable to present Himalayas before heavy erosion occurred. The Kazakhstania block collided with Baltica during the Cisuralian while North China Craton fused with Pangea by the period's end. Large continental interiors experienced extreme heat and cold variations alongside monsoon conditions with highly seasonal rainfall patterns. Deserts covered vast regions of Pangaea favoring gymnosperms over spore-dispersing plants. Three areas hold extensive Permian deposits: the Ural Mountains where Perm itself is located, China, and southwest North America including Texas red beds.
Synapsids thrived and diversified greatly during the Cisuralian epoch. Permian synapsids included large members such as Dimetrodon whose special adaptations enabled them to flourish in drier climates. They grew to dominate vertebrates replacing amphibians through a faunal turnover occurring between the Cisuralian and Guadalupian. This transition lasted about 20 million years from the Sakmarian to the end of the Kungurian. Predator-prey interactions among terrestrial synapsids became more dynamic. A global hiatus in the terrestrial fossil record known as Olson's Gap obscures details of this transition. Middle Permian faunas of South Africa and Russia were dominated by therapsids most abundantly diverse Dinocephalia. These creatures went extinct at the end of the Middle Permian during the Capitanian mass extinction event. Late Permian faunas featured advanced therapsids like predatory sabertoothed gorgonopsians and herbivorous beaked dicynodonts alongside large herbivorous pareiasaur parareptiles. Archosauromorpha first appeared and diversified during the Late Permian giving rise to pseudosuchians dinosaurs and pterosaurs. Cynodonts ancestral to modern mammals gained worldwide distribution during the Late Permion. Therocephalians such as Lycosuchus arose in the Middle Permian while Weigeltisauridae represented the oldest known gliding vertebrates with extendable wings.
The Permian ended with the most extensive extinction event recorded in paleontology labeled the Permian-Triassic extinction event. Ninety to 95 percent of marine species vanished along with 70 percent of all land organisms. It remains the only known mass extinction affecting insects. Recovery from this catastrophe took ecosystems 30 million years on land. Trilobites finally became extinct before the period's conclusion though Nautiloids surprisingly survived. Evidence shows magma poured onto Earth's surface as flood basalt in what is now called the Siberian Traps for thousands of years. This contributed to environmental stress leading to mass extinction. Worst-case scenarios suggest eruptions released enough carbon dioxide to raise world temperatures five degrees Celsius. Another hypothesis involves ocean venting of hydrogen sulfide gas destroying ozone layers allowing ultraviolet radiation to kill surviving species. Models indicate frozen methane reservoirs melting could expel potent greenhouse gases raising temperatures an additional five degrees Celsius. This explains why the first phase of extinctions was land-based followed by a marine-based second phase starting after increased C-12 levels then returning to land-based again. The Capitanian mass extinction event occurred around 260 million years ago corresponding to eruption of Emeishan Traps causing rapid climate change.
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Common questions
Who introduced the term Permian into geology and when?
Sir Roderick Impey Murchison introduced the term Permian into geology in 1841. He named it after the region of Perm in Russia following extensive explorations with Édouard de Verneuil near the Ural Mountains during 1840 and 1841.
When did the United States Geological Survey accept the Permian as distinct from the Carboniferous?
The United States Geological Survey finally accepted the Permian system as distinct from the Carboniferous in 1941. The system remained controversial for over a century before this official recognition occurred.
Where is the Global Boundary Stratotype Section and Point for the Asselian stage located?
The Global Boundary Stratotype Section and Point for the Asselian stage sits in the Aidaralash River valley near Aqtöbe, Kazakhstan. This boundary was ratified in 1996 and marks the first appearance of Streptognathodus postfusus.
What supercontinent formed during the Permian period?
During the Permian all Earth's major landmasses collected into a single supercontinent known as Pangaea. Microcontinental terranes like Cathaysia sat to the east while Pangaea straddled the equator extending toward the poles.
How many percent of marine species vanished during the Permian-Triassic extinction event?
Ninety to 95 percent of marine species vanished along with 70 percent of all land organisms during the Permian-Triassic extinction event. Recovery from this catastrophe took ecosystems 30 million years on land.