Permian

The Permian is a time period in Earth's history that lasted for 47 million years, from 298.9 million years ago to 251.902 million years ago. It was the sixth and last period of the Paleozoic Era, and it came before the Triassic Period, which is part of the Mesozoic Era. The idea of the Permian was first suggested in 1841 by a scientist named Sir Roderick Murchison, who named it after the region of Perm in Russia.

During the Permian, many types of animals that laid eggs on land, called amniotes, became more common. These included two groups: synapsids and sauropsids, which included reptiles. The world at that time had one huge landmass called Pangaea, surrounded by a giant ocean called Panthalassa. When big forests disappeared, drier conditions allowed these new land animals to thrive instead of their amphibian ancestors.

The Permian time had several big changes in animal life, and some scientists think there were major events where many species died out. By the end of the Permian, a huge event called the Permian–Triassic extinction, or the Great Dying, happened. It was the largest mass extinction in Earth's history, with most marine species and many land species disappearing. Life on Earth took a very long time to recover from this disaster.

Etymology and history

Before the term Permian was used, rocks of similar age in Germany were called the Rotliegend and Zechstein, and in Great Britain they were known as the New Red Sandstone.

The name Permian was created in geology in 1841 by Sir Roderick Impey Murchison, who was president of the Geological Society of London. He came up with the name after studying rocks near the Ural Mountains in Russia with Édouard de Verneuil. Murchison found many layers of different types of rock, like marl, schist, limestone, sandstone, and conglomerate, that came after the Carboniferous rocks in that area. He named this time period after the region of Perm in Russia, which was once part of an old kingdom called Permia and is now part of Perm Krai. Later, a scientist named Jules Marcou found similar rocks in North America, from the Mississippi River to the Colorado River, and suggested a different name, Dyassic, but Murchison did not accept it. For many years, people argued about the Permian name, and even in the United States, some scientists thought it was just part of the Carboniferous time until 1941.

Geology

The Permian Period is split into three epochs, called the Cisuralian, Guadalupian, and Lopingian. People often refer to these as the Early, Middle, and Late Permian. Scientists study rocks from this time and divide them into smaller parts called stages. These stages help experts compare rocks from different places around the world.

For many years, the Permian was simply split into Early and Late parts. But in the 1990s, scientists suggested a new way to divide it into three parts, and this idea was later accepted.

One way scientists used to study these old rocks was by looking at tiny, ancient sea creatures called ammonoids. However, these creatures are not often found in Permian rock layers. Instead, scientists now mainly use another group of ancient sea creatures called conodonts to help date these rocks.

Cisuralian

The Cisuralian name comes from rock layers found on the western slopes of the Ural Mountains in Russia and Kazakhstan. This name was suggested in 1982. It includes four stages: Asselian, Sakmarian, Artinskian, and Kungurian.

Guadalupian

The Guadalupian name comes from the Guadalupe Mountains in Texas and New Mexico, where many old ocean rock layers from this time can be seen. This name was used in 1902.

Lopingian

The Lopingian name comes from a place called Leping in Jiangxi, China. It was first used in 1923 and became an official part of the Permian timeline in 1995.

Regional stages

In Russia, the Tatarian Stage includes parts of the Lopingian and Guadalupian. In North America, the Permian is split into different stages like the Wolfcampian, Leonardian, Guadalupian, and Ochoan. In New Zealand, the Permian is divided into three epochs with several smaller stages.

Paleogeography

During the Permian period, all of Earth's big land areas came together to form one huge landmass called Pangaea. This land stretched from the equator to near the poles, changing the way oceans moved around the world. One large ocean, called Panthalassa, covered most of the planet, while another ocean, the Paleo-Tethys Ocean, sat between Asia and another land area. Over time, parts of these lands moved, causing oceans to shift and change.

The climate on Pangaea varied a lot, with very hot and very cold areas. Deserts were common, and this helped certain plants, like early trees such as conifers, ginkgos, and cycads, to thrive. Important areas for studying this time include the Ural Mountains, parts of China, and areas in the southwestern United States, such as Texas and New Mexico. The Permian Basin in these U.S. states has some of the thickest rock layers from this period.

Climate

The Permian period was cooler than many other times in Earth's history, with gentle temperature changes from the poles to the equator. At the start of the Permian, Earth was in a cold phase known as the Late Paleozoic icehouse, which began earlier in the Devonian period and lasted through the Carboniferous period. As the Permian began, the climate started to warm and become drier, especially near the equator.

Later in the Permian, there were periods of cooling and warming. One warm period, called the Artinskian Warming Event, caused glaciers to shrink, though some ice remained in places like Australia and Siberia. Another cool period happened around the middle of the Capitanian stage, known as the Kamura Event. The end of the Permian saw a huge burst of carbon dioxide from volcanic activity in what is now Siberia, leading to a massive warming and a major extinction event. The climate of the Permian also had strong seasons, with heavy rains in some areas and very dry conditions in others.

Life

The Permian period was a time when many kinds of animals and plants lived in the oceans and on land.

Marine biota

The oceans during the Permian had many shells, strange brachiopods, and spiny echinoderms. Brachiopods were very common and played important roles in the underwater world. Ammonoids, like Goniatitida, were also important but became less common later in the Permian. Trilobites, which had been around for a long time, were few in number during the Permian.

Terrestrial biota

On land, the Permian had many plants, fungi, bugs, and early reptiles. Big deserts covered parts of the world, and the climate was dry. Plants changed a lot during this time. Trees like Lepidodendron and Sigillaria were replaced by seed ferns and early conifers. Forests were rich and diverse, with many different kinds of plants growing.

Insects

Insects became more diverse during the early Permian. There were many different kinds of insects, including early damselflies, dragonflies, and beetles. Some insects were very large, and others had special ways to protect themselves from plants.

Tetrapods

Early land animals included different kinds of synapsids, like Dimetrodon. These animals were important because they could live in drier places. Later, more advanced therapsids appeared, which would lead to mammals.

Amniotes

Synapsids, the group that would become mammals, were very successful during the Permian. They included large animals like Dimetrodon. Therapsids became common, and some of them, like gorgonopsians and dicynodonts, were important predators and herbivores. New groups of reptiles also appeared, like the first Archosauromorpha, which would later give rise to dinosaurs.

Amphibians

Amphibians were also around during the Permian. Temnospondyls were common but became less diverse later on. Embolomeres, which looked like crocodiles, lived in water and were around until the end of the Permian.

Fish

Fish were not as diverse during the Permian as they would become later. Bony fishes called Paleopterygii were common, and coelacanths had their highest diversity at the very end of the Permian. Lungfish were important in freshwater, and some sharks, like Helicoprion, were known for their unusual teeth.

Flora

Plants during the Permian were different in different parts of the world. In some places, forests were made of lycopsids, while in others, tree ferns and conifers were common. The climate became drier, which helped conifers spread. New plants like ginkgoales and cycads appeared, and forests became more widespread.

Permian–Triassic extinction event

The Permian period ended with a huge loss of life known as the Permian–Triassic extinction event. About 90 to 95% of sea creatures and 70% of land animals did not survive. Even insects, which had been around for a long time, disappeared. It took a very long time for life to recover on land—about 30 million years.

Scientists think that huge eruptions of lava in an area now called the Siberian Traps caused a lot of problems for plants and animals. These eruptions may have released gases that warmed the planet and made it hard for many species to live. Some researchers also suggest that a gas called hydrogen sulfide, produced by special bacteria in the deep ocean, might have risen and harmed life on Earth. Another idea is that warming from the lava eruptions caused frozen methane under the ocean to melt, releasing even more heat-trapping gases into the air.