The Permian Period

The Permian Period

300 mya - 250 mya

Sir Roderick Murchison, a Scottish geologist, named the Permian Period after the ancient kingdom of Permia (and the present city of Perm, near the Ural Mountains) in 1841. The Permian is the last period of the Paleozoic,following the Carboniferous Period, and precedes the first Period of the Mesozoic. The early Permian saw the emergence of Pangaea, the earth's second supercontinent (the one before had been the supercontinent of Rodinia in the late Proterozoic), as Gondwana and Euramerica--the two great continents of the Paleozoic--collided in an uproar that raised the modern-day Ural Mountains. Pangaea took the shape of a thick "C": India, Australia, and Antarctica made up the bottom curve, Africa hugged the middle curve, North and South America climbed up the back, and Europe and Asia formed the top curve. The Tethys Ocean sat inside the "C". 

let's be real: it's more of a Pac-Man than a "C"

Another notable body of water was the Zechstein sea, a shallow, salty inland ocean catering to bivalves and brachiopods, which could cope with the salinity. Hardly anything is known about the deeps of Panthalassa, the global ocean, but reefs laden with corals and sponges developed in the coastal waters. Ammonites, brachiopods, nautiloids, and gastropods continued into the Permian Period, but the lobe-finned and spiny fishes (ancestors to the amphibians of the Carboniferous) were being outdone by true bony fish. And, of course, sharks kept doing their thing.

Helicoprion, a contemporary shark of the Permian

The Permian started with an Ice Age, and consequently had poles covered ice and glaciation. The climate warmed up towards the middle of the Period, and the glaciers receded and the interiors became drier. Swampy areas dried out, and the mossy, fern-like plants that had excelled in the Carboniferous were hard-pressed to complete with a new type of plant, the gymnosperm. Gymnosperms had two advantages on the competition: it was a vascular plant, meaning that it could transport its water internally (perfect for a drier climate), and it reproduced via seeds encased in a shell. The gymnosperm's success resulted in the rise of cycads and gingkoes, and the genius of its design is seen in the vast conifer forests around the world today. The interior of Pangaea became warm and arid; those animals that could lay eggs on land or incubate their offspring internally had an edge in this new state of affairs. The amphibians that had flourished in the swamps found their habitats drying up along with their options, and their numbers began to shrink. Amniotes--ancestors of mammals, turtles, lepidosaurs (reptiles with overlapping scales) and archosaurs--overran their amphibious competition and made some pretty incredible leaps and bound, exemplified in the images below (the first representative of the early Permian and the second representative of the late Permian):

Terrestrial animals of the Permian fall into two categories: the synapsids and the sauropsids. The synapsids ("fused-arch") had a temporal fenestrae (or opening) in each eye, resulting in a bony arch; these animals are also known as "theropsids" ("beast-face"). The therapsids were a subgroup of the synapsids, and this group included the "dog-toothed" Cynodonts, which probably hunted in packs and which are the ancestors of modern mammals (including you and me!). 

Pristerognathus, a fierce little therapsid

Many therapsids had whiskers, which indicates they probably had fur and were endothermic (or warm-blooded). Though the non-mammalian types are often referred to as "mammal-like reptile," this is a misnomer, since they were not reptiles or mammals; it'd be more apt to say they are reptile-like mammals, since they are closer to mammals than reptiles. The synapsids lacked epidermal scales, and many had rows of osteoderms and horny scutes (think croc skin). The synapsids were the largest terrestrial vertebrates of the Period, and some of the most-known include the carnivorous Dimetrodon and Edaphosaurus. Lystrosaurus is a good example of herbivorous synapsids.

Dimetrodon, an infamous synapsid. Though often mistaken for a dinosaur,
Dimetrodon is more closely related to mammals than dinosaurs. The fin
on its back was probably used for regulating its body temperature or
for mating displays.

Lystrosaurus being attacked by an ancestor of the crocodile.

The sauropsids ("lizard-faced") group is virtually synonymous with reptiles, and it includes the archosaurs that would diversify in the Triassic and lead to the dinosaurs. Less gloriously, insects continued to diversify: the Permian Period saw the emergence of true bugs (ones able to pierce and suck plant material); flies, beetles, and cicadas came onto the scene. 

The Permian Period came to an abrupt and brutal end around 250 million years ago: the worst extinction in earth's history, the Permian-Triassic Extinction, took place in the blink of a geologic eye (100,000 years) and wiped out 90-95% of the planet's marine species and 70% of its terrestrial species. So infamous is this extinction that most people are unaware that the Permian had a previous extinction, albeit one that pales in comparison. The cause of this extinction is unknown, though some speculate the cause was volcanic activity in northern Pangaea instigating a "nuclear winter."


Gallery: Artwork of the Permian

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