PERMIAN: CHARACTERISTICS, DIVISIONS, GEOLOGY, FLORA AND FAUNA - GEOGRAFÍA - 2025

The Permian was the sixth period of the Paleozoic era, between the Carboniferous and the Triassic (Mesozoic era). It lasted for approximately 48 million years and it can be said that it was a time of transition for the planet, both geologically and climatic.

During the Permian period, a large number of transcendental changes occurred at the biological level, such as the first sketch of mammals, in the figure of the so-called mammalian reptiles, as well as the diversification and expansion of the rest of the living beings that existed.

Permian fossil exhibit. Source: Emilio J. Rodríguez Posada

This period has been very well studied by specialists, especially its end, since here the most catastrophic and devastating mass extinction event on the planet took place (more than the one that caused the extinction of the dinosaurs).

In this, commonly known as "the Great Dying", more than 90% of the species of living beings disappeared. During this event, the conditions of the planet changed in such a way that life on the planet was practically unviable.

Only a few species survived, which later gave way to the most famous animals of prehistory: dinosaurs.

General characteristics

Duration

The Permian period lasted approximately 48 million years. It began 299 million years ago and ended 251 million years ago.

Variable weather

During this period, the Earth experienced a relatively variable climate, since both in its beginning and in its end glaciations were observed, and during its intermediate phase, the climate was quite hot and humid, especially in the equatorial zone.

Evolution of certain species of animals

In the Permian period, some species of animals underwent great diversification. Such is the case of reptiles, which were considered as mammals, since, according to fossil records, they could be the ancestors of current mammals.

The Great Dying

It was a mass extinction event that occurred at the end of the Permian period and the beginning of the following period, the Triassic. It was the most devastating extinction process that the planet has gone through, since it wiped out approximately 90% of the species of living beings that populated the planet.

There are many causes that have been postulated to explain this event. Among the most accepted is an intense volcanic activity that caused the expulsion of a lot of carbon dioxide into the atmosphere, which contributed to raising the environmental temperature.

Likewise, the release of carbohydrates from the bottom of the oceans and the impact of a meteorite have been proposed as causes.

Whatever the causes, this was a fairly catastrophic event that greatly affected the environmental conditions of planet Earth.

geology

The Permian period began immediately after the Carboniferous period. It is important to note that at the end of the Carboniferous the Earth experienced an ice age, so that in the Permian there were still traces of this.

Likewise, during this period, the supercontinent Pangea was almost entirely united, only a few small pieces of land remained outside, such as the southeast of the Asian continent.

During this period, a part of Pangea, specifically Gondwana, split up and began to move north. This fragment was called Cimmeria.

This continent contained the territories of what is now Turkey, Tibet, Afghanistan, and some Asian regions such as Malaysia and Indochina. The separation and subsequent displacement of Cimmeria caused the Paleo Tethys ocean to close, until it disappeared.

Finally, already in another period (Jurassic), this continent would collide with Laurasia, giving rise to what was known as the Cimmerian Orogeny.

Likewise, the sea level was low, which corresponds to what also happened during the previous period, the Carboniferous. Similarly, during this period the Hercynian Orogeny had its final phase.

Hercynian Orogeny

As is well known, this was a process of mountain formation, caused by the movement and collision of tectonic plates. It lasted about 100 million years.

This orogeny mainly involved the collision between two supercontinents: Gondwana and Laurasia. As in any supercontinent collision process, the Hercynian orogeny generated the formation of large mountain ranges that are believed to have peaks similar in height to those of the Himalayas.

However, they are only speculations by specialists based on fossil records and projections, since these mountains disappeared as a result of natural erosion.

It is important to note that the Hercynian orogeny played a major role in the formation of the Pangea.

Existing oceans

In the Permian period, land masses were not the only ones to undergo transformations. Some bodies of water were also transformed and modified.

• Panthalassa Ocean: it continued to be the largest and deepest ocean on the planet, a precursor to the current Pacific Ocean. It was encircling the entire continental masses.
• Paleo Ocean - Tethys: this continent was occupying the "O" of the Pangea, between the territories of Gondwana and Laurasia. However, when Cimmeria separated from Gondwana and began its slow movement northward, this ocean slowly closed, until it became a sea channel.
• Thetis Ocean: began to form during this period, as a result of the displacement of Cimmeria to the north. As the Paleo-Tethys ocean closed, this ocean began to form behind Cimmeria. It occupied the same place that Paleo Tethys occupied. It was baptized with that name in honor of the Greek goddess of the sea, Thetis.

Weather

During the Permian period the climate underwent certain modifications. The first thing to note is that this period began and ended with glaciations. At the beginning of the period, part of Gondwana was covered with ice, especially towards the south pole.

Towards the equatorial zone, the climate was much warmer, which facilitated the development and permanence of various living beings, as shown by the fossil records.

As time progressed, the planet's climate stabilized. Low temperatures were limited to the poles, while a warm and humid climate continued to exist in the equatorial region.

This was so in the areas near the ocean. Kilometers into the Pangea, the story was different: the climate was arid and dry. According to the opinion of specialists, there were possibilities that in this territory there would be alternation of seasons, with intense rains and prolonged droughts.

Towards the end of the period there was a decrease in environmental temperature, which was followed by a significant increase in it, produced by various causes according to various hypotheses: volcanic activity and the release into the atmosphere of various gases such as carbohydrates, among others.

Flora

During this period, atmospheric oxygen levels were slightly higher than they are today, allowing a number of life forms to flourish, both botanical and zoological.

In the Permian period, plant life diversified to a great extent. Some of the plants that had dominated during the Carboniferous continued to exist.

The fern group in particular declined markedly during this period. Similarly, in the equatorial region there were jungles, which could develop thanks to the favorable climate of this area.

Likewise, the type of plant that dominated during the Permian period were gymnosperms. It is important to remember that these plants belong to the group of plants with seeds, their essential characteristic being that their seed is "naked". This means that the seed does not develop in an ovary (as in angiosperms).

Among the gymnosperms that made their appearance on Earth, we can mention the ginkgos, conifers and cycads.

Ginkgos

The first specimens of this group are believed to have appeared in the Permian period. These were dioecious plants, which means that there were individuals with male reproductive organs and plants with female reproductive organs.

These types of plants were arborescent. Its leaves were wide, fan-shaped and it is even estimated that they could reach measures of 20 cm.

Almost all the species became extinct, currently only one species is found, the Ginkgo biloba.

Conifers

They are plants that owe their name to the structure in which their seeds are stored, the cones. The first representatives of this group emerged in this period. They were monoecious plants, with the reproductive structures, female and male in the same individual.

These plants can adapt to extreme environments, such as very cold ones. Its leaves are simple, needle-shaped and evergreen. Its stems are woody.

Cicadaceae

These types of plants have managed to survive to this day. Its characteristics include its woody stem, without branches, and its pinnate leaves that are located at the terminal end of the plant. They were also dioecious; they presented female and male gametes.

Close up view of a cycad. Source: Bruno da Silva Lessa (email: brunoslessa (at) yahoo (.) Com (.) Br, via Wikimedia Commons

Fauna

In the Permian period some species of animals that had their origin in previous periods such as the Devonian or the Carboniferous were kept.

However, during this period an important group of animals emerged, the mammalian reptiles, which are considered by specialists as the ancestors of today's mammals. Likewise, in the seas life was also diverse.

Invertebrates

Within the group of invertebrates, some marine groups such as echinoderms and mollusks stood out. Various fossil records of bivalves and gastropods, as well as brachiopods, have been found.

Similarly, within this group and in the marine ecosystems, the members of the poriferous edge (sponges) stood out, which were part of barrier reefs.

There was a species of protozoan that reached great diversification and development during this period, the fusulinids. Although they became extinct, an abundant fossil record has been found, so much so that more than 4 thousand species have been identified in the fossils. Their distinctive feature was that they were protected by a cover of calcareous material.

On the other hand, arthropods, especially insects, remained, at least initially, as in the Carboniferous. It should be noted that the size of the insects was quite significant.

An example of this was Meganeura, the so-called “giant dragonfly”, as well as other members of the group of arachnids. However, as time progressed, the size of these insects gradually decreased. Specialists have indicated that this was perhaps due to a reduction in atmospheric oxygen levels.

Finally, within the group of arthropods, several new orders appeared in this period, such as the Diptera and the Coleoptera.

Vertebrates

Vertebrates also experienced great expansion and diversification, both in aquatic and terrestrial ecosystems.

Fishes

Among the most representative fish of this period are chondrichthyans (cartilaginous fish), such as shark and bony fish.

Hybodus

This belonged to the group of chondrichthyans. It was a type of shark that became extinct in the Cretaceous period. According to the data collected, it is believed that he could have a mixed diet, since he had teeth of different shapes, adapted to different types of food.

They were very similar to today's sharks, although it was not large, since it could only reach about 2 meters in length.

Orthacanthus

It was an extinct type of fish. Although it belonged to the group of sharks, its appearance was quite different. It had a long and somewhat thin body, similar to that of an eel. He also had several types of teeth, which allows us to infer that he could have a varied diet.

Amphibians

In this period there were several tetrapods (with four legs). Among these, one of the most representative was the Temnospondyli. It had its peak during the Carboniferous, Permian and Triassic periods.

This was a fairly diverse group, the size of which could range from a few centimeters to about 10 meters. Its limbs were small and its skull was elongated. Regarding its diet, it was a carnivore, essentially a predator of small insects.

Reptiles

This was a group that experienced great diversification. In this period the so-called therapsids stood out, as well as the pelycosaurs.

Therapsids

It is a group of animals that are believed to be the ancestors of today's mammals. Because of this, they are known as mammalian reptiles.

Among their distinctive characteristics, it can be mentioned that they presented several types of teeth (like modern mammals), each one adapted to different functions. They also had four limbs or legs and their diet was varied. There were carnivorous and other herbivorous species.

Dicynodonts

This type of therapsids had a fairly compact body, with strong and short bones. Likewise, its teeth were quite small and its snout was modified into a beak. When it came to food, it was purely herbivorous.

Cynodonts

They were a group of small animals, the largest being 1 meter in length. Just like current mammals, they had different types of teeth, specialized for different functions such as tearing, cutting or grinding.

Specialists believe that this type of animal could have had a body covered with hair, which is one of the distinctive characteristics of the group of mammals.

Pelycosaurs

It was a group of animals that had a somewhat compact body, with four short limbs and a long tail. Likewise, on their dorsal surface they had a wide fin that, according to experts, allowed them to regulate body temperature to keep it constant.

Mesosaurus

Special mention should be made of this reptile typical of freshwater ecosystems, where it was a recognized predator. Its body was longer than it was tall, and it also had an elongated snout with long teeth. Externally they resembled current crocodiles.

Representation of a Mesosaurus. Source: Nobu Tamura (http://spinops.blogspot.com), from Wikimedia Commons

Divisions

The Permian is divided into three epochs, which, in turn, span nine ages.

Cisuralian

It was the first division of this period. It lasted 29 million years and in turn was made up of four ages:

• Asselian (299 - 295 million years)
• Sakmarian (293 - 284 million years)
• Artinskian (284 - 275 million years)
• Kungurian (275 - 270 million years)

Guadalupian

Second division of the period. With a duration of 5 million years. It was made up of three ages:

• Roadian (270 - 268 million years).
• Wordian (268 - 265 million years)
• Capitanian (265 - 260 million years)

Lopingian

It was the last division of the period. It lasted 9 million years. The ages that made it up were:

• Wuchiapingian (260 - 253 million years)
• Changhsingiense (253 - 251 million years.

References

1. Bagley, M. (2014). Permian Period: climate, animals & plants. Retrieved from: Livescience.com
2. Castellanos, C. (2006). Extinction: causes and effects on biological diversity. Luna Azul Magazine. 23. 33-37
3. Emiliani, C. (1992) Planet Earth: Cosmology, Geology, and the Evolution of Life and Environment. Cambridge: Cambridge University Press
4. Henderson, C., Davydov, W., Wardlaw, B., Gradstein, F. (2012). The Permian Period.
5. Sour Tovar, Francisco and Quiroz Barroso, Sara Alicia. (1998). The fauna of the Paleozoic. Science 52, October-December, 40-45.
6. Van Andel, T. (1985), New Views on an Old Planet: A History of Global Change, Cambridge University Press