System (period) Series Stage (age) Lower boundary, Ma
Triassic Lower Induan 251.902±0.024
Permian Lopingian Changhsingian Golden spike254.14±0.07
Wuchiapingian Golden spike259.51±0.21
Guadalupian Capitanian Golden spike264.28±0.16
Wordian Golden spike266.9±0.4
Roadian Golden spike273.01±0.14
Cisuralian Kungurian 283.5±0.6
Artinskian Golden spike290.1±0.26
Sakmarian Golden spike293.52±0.17
Asselian Golden spike298.9±0.15
Carb. Pen. Upper Gzhelian older
Subdivisions and "golden spikes" according to IUGS as os September 2023[1]

The Permian is a geologic period and system which extends from 298.9 ± 0.15 to 251.902 ± 0.024 (Million years ago). It is the last period of the Paleozoic Era, following the Carboniferous Period and preceding the Triassic Period of the Mesozoic Era. It was first introduced in 1841 by geologist Sir Roderick Murchison, and is named after the ancient kingdom of Permia. 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 a single supercontinent known as Pangaea, surrounded by a global ocean called Panthalassa. The extensive rainforests of the Carboniferous had disappeared, leaving behind vast regions of arid desert within the continental interior. Reptiles, who could better cope with these dryer conditions, rose to dominance in lieu of their amphibian ancestors. The Permian Period (along with the Paleozoic Era) ended with the largest mass extinction in Earth's history, in which nearly 90% of marine species and 70% of terrestrial species died out. It would take well into the Triassic for life to recover from this catastrophe.

This was the period when the first group of large animals ever returned to water-the mesosaurs. The permian period was the last period of the paleozoic era and preceded the Triassic period. This was when dicynodonts and pareiasaurs were at the peak of their evolution since they were the dominant herbivores at the time and some grew up to the size of a rhino or hippo. The biggest carnivores were the pelycosaurs and gorgonopsids such as Inostrancevia alexandri. These carnivores grew up to the size of a large bear or tiger. Contrary to popular belief. Dimetrodon lived and went extinct in the Permian period and never lived alongside the dinosaurs which wouldn't be around for another 22 million years. This was also the time when the first synapsids were appearing. These were creatures with two postorbital openings. These animals would give rise to the first true mammals in the late Triassic.

Permian subdivisions[]

The Permian system is divided into three series (geochronological equivalent is an epoch): Cisuralian, Guadalupian and Lopingian, and each of them is divided into several stages (geochronological equivalent is an age). Asselian, Sakmarian, Artinskian and Kungurian are parts of the Cisuralian; Roadian, Wordian and Capitanian are parts of the Guadalupian; finally, Wuchiapingian and Changhsingian are parts of the Lopingian. Cisuralian series has been moved to the International stratigraphic chart from the regional Russian one, while Guadalupian and Lopingian were originally used in US and China, respectively.

In Russia, the type locality of the Permian system, its subdivisions are slightly different. The additional Ufimian stage is distinguished above the Kungurian (thus, there are five stages in the Cisuralian series), although its lower boundary and age have not been established, and therefore a number of researchers consider it to be the upper part of the Kungurian stage. The places of Guadalupian and Lopingian are occupied by the Biarmian and Tatarian series, respectively. Biarmian is subdivided into Kazanian and Urzhumian stages, while Severodvinian and Vyatkian stages are united into the Tatarian series. The lower boundary of the Biarmian compares well with that of the Guadalupian. The reason why the Biarmian and Tatarian divisions are not included in the international scale is that their boundaries within the East European Plain are determined by freshwater and continental sediments, which are poorly correlated worldwide. The divisions of the Guadalupian and Lopingian series are determined by marine sediments, which make their correlation easier.

Terrestrial biota[]

Lycopods became extinct in the Permian, as well as the extinction of 8 insect Orders. Early conifers, tree ferns, ginkos and cycads appear with first plant fruiting structures also appearing. Beetles are evidenced as feeding on these fruting structures and possibly pollinating them as well.