All About the Permian Period: The Era of the Pangaea


This system, named in 1841 by British geologist Roderick Impey Murchison after the region of Perm in Russia where it can be found, is distinguished by a thick layer of limestone above the Carboniferous rock layers. Before officially designating this system, Murchison established how Permian strata could be distinguished in various locations due to their characteristic fossils.

The Permian was the final era of the Paleozoic Era regarding geologic time. The Permian period lasted from the Carboniferous's conclusion to the Triassic period's beginning, or 298.9 to 252.2 million years ago.

The Emergence Of Pangaea

Permian Period

Photo: Ianm35 via Getty Images

During the Permian Period, all of the world's supercontinents collided to form a super-supercontinent that stretched from pole to pole—Pangaea.  The eastern side of Pangaea resembled the letter "C," making it an unusually symmetrical continent.

The Tethys Sea was nestled in the cupped opening of the letter C. The Pacific basin's eastern border coincided with a lengthy subduction zone along the "C" spine. Panthalassa, a vast ocean, covered much of Earth's surface.

The collision of continents resulted in arid environments, much as large deserts are situated within the interior of most modern continents. Only some areas of this enormous supercontinent received precipitation all year round, and extreme seasonal changes occurred since there were no large bodies of water in the immediate geographical area.

Pangaea's development also decreased the overall area of the coastline and hence the quantity of coastal marine habitat, which may have contributed to the extinction event after the period.

What Lived During The Permian Period?

Because of its massive size, the newly formed supercontinent Pangaea brought catastrophic climatic and environmental conditions. Much of the southern hemisphere was covered in ice caps, making it chilly and dry. 

More and more northern regions experienced extreme heat and large variations in precipitation throughout the year. After the Carboniferous period, drought-resistant plants such as conifers and seed ferns began to replace the previous, more abundant swamp forests.

Early reptiles were well-positioned to take advantage of the favorable conditions. Thanks to their thicker, more moisture-retaining skins, they could establish a foothold in ecosystems that amphibians had formerly dominated. They evolved into well-adapted species to the arid environments in which they now thrive.

The Permian world was dominated by two major animal groups: synapsids and sauropsids. Synapsids have solitary temporal openings in their skulls and are believed to represent the ancestry that evolved from mammals. On the other hand, the sauropsids were the progenitors of dinosaurs and birds and had two separate skull apertures.

The Synapsids

For a while during the early Permian, it looked that synapsids would dominate the land. The group was quite diverse. The pelycosaurs were the oldest and most basic synapsids; among them was the top predator Dimetrodon.

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Similar to a lizard but with a larger bony "sail" fin on its back, Dimetrodon likely employed this adaptation to control its body temperature. Recent studies have revealed that the Dimetrodon's skull, jaws, and teeth are more similar to those of mammals than those of reptiles, despite the animal's lizard-like form.

In the late Permian, a new bloodline known as therapsids replaced pelycosaurs. These creatures were a lot more mammalian-like. The placement of their legs underneath them gave them the more vertical posture characteristic of quadruped animals. Their jaws were stronger, and there was more variation in their teeth.

Certain species possessed fur and were endothermic, as evidenced by the presence of whiskers on fossilized skulls. Groups of cynodont ("dog-toothed") animals often worked together to hunt. The cynodonts were the presumed originators of all present-day mammals.

Procynosuchus, or "before dog crocodile," was the earliest cynodont to be identified, dating back to around 254 million years ago in South Africa's Karoo region in the 1930s. Like modern seals and crocodiles, Procynosuchus was a semi-aquatic creature that moved through the water by wriggling the ends of its rigid spine and paddling with webbed paws and hands.

The Sauropsids

Sauropsids are an incredibly diversified group of largely egg-laying vertebrates. All living and extinct reptiles, excluding synapsids, are included under the Sauropsida. Today, we consider lizards, snakes, turtles, crocodiles, and even birds to be living sauropsids. Other than birds, extinct sauropsids include pterosaurs, plesiosaurs, ichthyosaurs, and many more.

In that it was the very first pterosaur to be named, the Pterodactylus is considered the "father" of pterosaur paleontology. Some experts first described the species as resembling a bat; nevertheless, a definitive identification took quite some time to emerge.

The Plesiosaur was likely the family that influenced the mythological Nessie. The largest ever to exist in the oceans, the Liopleurodon, grew to a length of up to 25m (82 ft). The predatory beast had a large head (about 3 meters or 10 feet) but a short neck and four strong flippers.

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Shonisaurus was formerly supposed to be the biggest ichthyosaur due to a collection of extremely huge specimens assigned to the genus. ‭Later research determined, however, that these fossils were more accurately associated with a different genus called Shastasaurus. ‭ ‬ As of today, we know that the longest Shastasaurus ever discovered was at least 21 meters in length.

The Permian-Triassic Extinction Event

Large reefs dotted the shallow ocean floor, and the variety of life was remarkable. There were abundant types of ammonites and brachiopods. Most fossil material is buried, so we don't know much about life in the Panthalassic Ocean's depths, but we do know that cartilaginous fishes like sharks and rays were prevalent and that genuine bony fishes were on the rise.

Because of the abrupt climate change during the Permian's end, around 95% of marine species and 70% of terrestrial species became extinct in a very short amount of time (in geologic terms). 

Insects suffered one of the few major extinctions we know of now. Likewise, many flora species became extinct. Fossil records show widespread coniferous forests in present-day Europe disappeared sometime during the Permian period. Most likely, thanks to the amount of dead plant and animal material available for them to consume, fungi were less affected than other creatures.

The Permian mass extinction is so devastating that it has been given the moniker "The Great Dying." 

Its effects may still be seen today. Many species of gastropods and brachiopods perished, paving the way for the dominance of bivalves, which were not very common among the marine fauna of the Permian period. Present-day bivalves continue to populate today's oceans at high densities.

What Caused The Great Dying?

Permian Period

Photo: Jagoush via Getty Images

Researchers have not settled on a single theory to explain what triggered the Great Permian Extinction. Whether it occurred slowly over thousands of years or suddenly as a result of cataclysmic events is unknown.

Theory #1: Volcanic Eruptions

An enormous volcanic eruption that generated flood basalts, sometimes called Siberian Traps, is often cited as a potential cause of the extinction. As one of the greatest volcanic occurrences on Earth, the eruption blanketed around 2,000,000 square kilometers with lava. 

Massive quantities of carbon dioxide may have been released into the atmosphere due to the eruptions, leading to rapid global warming of far more than 10 degrees Celsius on land and roughly 8 degrees Celsius on the surface of the oceans. Several food chains may have collapsed because of the eruptions' potential to send acid aerosols and dust clouds into the sky, which would have blacked out the sun and impeded photosynthesis.

Theory #2: The Emergence of Pangaea

The formation of the supercontinent Pangaea is another likely cause. However, it occurred gradually over many millennia. During the Permian, when Pangaea was fully developed, the amount of shallower aquatic ecosystems shrank significantly. 

The majority of oxygen in the atmosphere comes from these relatively shallow areas in the ocean. Earth's oxygen supply may have dropped without them. Many creatures that played crucial roles in the foundation of food webs might also be found in these regions. 

When the habitats of these creatures dwindled, so did the amount of food available to the marine ecosystem. The emergence of Pangaea may have also modified ocean circulation, altering ocean nutrient flow and influencing global weather systems.

Theory #3: Asteroids 

An impact event, like the one that wiped the dinosaurs at the end of the Cretaceous Period, is another theory for the extinction's origin. Possibly two or three separate extinction events occurred throughout the Permian period. 

Two or more independent collisions may have caused this pulsing. Craters in Australia, rare examples of shocked quartz in Australia and Antarctica, and meteorite fragments all indicate the possibility of impact occurrences. I

If a meteor (or three) struck Earth during the Permian period,  it would have fallen into the ocean. Any collision trace is likely long gone, as the ocean floor is regenerated by tectonic action every 200 million years. 

Cheers!

~GB


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