The Permian Period290-248 MY

Jarðsaga 1

-Saga Lífs og Lands –

Ólafur Ingólfsson

The Permian period was named in 1841 byMurchison after a tour of Russia, to include the"vast series of beds of marls, schists, lime-stones, sandstones, and conglomerates" that overlay the Carboniferous formations in the eastern part of the country. He named it after the ancient kingdom of Permia and the present city of Perm near the Ural mountains.

The Permian Period marked great changesin Earth's climate and environments:• Trilobites and other marine groups became extinct, anda group of small reptiles (diapsids) abound. These werethe ancestors to most modern reptiles and the rulingdinosaurs as well as pterosaurs and crocodiles. Thriving also, were the early ancestors to mammals (synapdia), which included some large reptiles such as dimetrodon.

• Reptiles grew to dominance among vertebrates, because their special adaptations enabled them to flourish in the drier climate. The warm zone spread in the northern hemisphere, where extensive dry desert appeared. The rock formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover.

Vast Continent, Vast Ocean• The global geography of the Permian included massive areas of land and water.

• By the beginning of the Permian, the motion of theEarth's crustal plates had brought much of the totalland together, fused in the Pangea supercontinent. Many of the continents of today in somewhat intact form met in Pangea (only Asia was broken up at the time), which stretched from high northern latitudes to the southern pole.

• Most of the rest of the surface area of the Earthwas occupied by a corresponding single ocean, known as Panthalassa, with a smaller sea to the east of Pangea known as Tethys.

Permian configuration of continents

Early Permian Climate

Much of the Southern Hemisphere was covered by ice. Coalformed in Equatorial rainforests and in temperate forests during the warmer "Interglacial" periods.

Permian climate development: a journey between end

members in climate

Climate development through the Permian

• As the Permian opened, glaciers continued to covermuch of Gondwana, as they had during the late Carboni-ferous. At the same time the tropics were covered in swampy forests.• Towards the middle of the period the climate becamewarmer and milder, the glaciers receded, and thecontinental interiors became drier. Much of the interiorof Pangea was probably arid, with great seasonal fluctuations (wet and dry seasons), because of the lack of the moderating effect of nearby bodies of water.• This drying tendency continued through to the latePermian, along with alternating warming and cooling periods.

Permianclimatezones

Permianwater-masses

Permian Life in the OceansThe warm shallow oceans swarmedwith life, very similar to Carboniferous forms.• The marine life of the period was per-haps more diverse than that of moderntimes. Ammonities were very abundant. Stromatolites, algae, foraminifers, corals, bryozoa and calcareous sponges built great reefs which in turn provided homes and shelter for active animals like ammonoids, nautiloids, gastropods and fish. Ray-finned fishes and sharks developed strongly...

Development of plants...The early Permian saw the continuation of the Carboni-ferous biomes, with polar tundra regions and warm wettropical swamp forests. The drying climatic tendency during the mid Permian spelled death for the mighty swamp forests.

Lycopods (jafnar) and sphenopsids (elftingar) weregreatly reduced in size, becoming mere shrubs. Plant lifeconsisted mainly of ferns (burknar) and seed-ferns, withnew plants like conifers and ginkgos coming into prominence. The increased importance of gymnosperms (berfrævingar) probably reflects development towards colonization of dryer habitats.

The Glossopteris flora was dominating in Gondwana. Itis gradually replaced by the seed-fern Dicroidium as the climate dries in the Late Permian.

Plant life on land

An Early Permian landscape in Europe. The form in theright foreground is the seed-fern Autunia, and in the leftbackground is a tree fern. The conifer in the right background is Walchia, while the plants around the pond are sphenophytes (elftingar). This community represents a seasonally dry savanna-like biome of the tropics.

Permian Conifers Conifers are hinterland elements which typically show severaladaptations for survival in drierhabitats. Towards the very endof the Carboniferous and during the Permian conifers became more common and in the Late Permian most European floras were dominated by conifers.

The amphibians grew to huge predators...

Eryops was a massive Permian amphibian reaching 2 m inlength. This meat-eater had a stout body with very wideribs, a strong spine, short and strong legs, a short tail, and a wide, skull with many sharp teeth in strong jaws.

SeymouriaSeymouria was anotherpredatory Early Permianamphibian. It was about60 cm long, with a strongbackbone, short, sturdy legs, and a short tail. Its long boned feet and digits were almost like that of a reptile.

Rise of the ReptilesMost skeletal differences between the earliest

reptiles and their amphibian ancestors were minor – the important diffrence was the mode of reproducing -

By early Permian, the pelicosaurs (fin-backedreptiles) had become the top carnivores of wide-spread ecosystems. Their fossil occurrances suugest they were primarily swamp-dwellers.

The Pelicosaurdynasty

The pelycosaur dynasty, included the large finbacks of the early Permian such as the Dimetrodon, which attaineda lengths some 3 meters. The large dorsal "sails" weremost certainly thermoregulatory devices that would heat up the animal in the cold morning, making it more active and giving it an advantage over it's more sluggish sail-less relatives. These animals were limited to the equatorial tropics.

Another Early Permian reptile:The name of this creature, Eudibamus cursoris, translatesas "original runner on two limbs" - the oldest knownexample of a bipedal reptile. The skeletal remains suggestthat Eudibamus could sprint upright on its long hind limbs, using its tail for balance. Why did this reptile require such a swift foot? A small herbivore (<50 cm) like Eudibamusmost likely used its speed to escape predators.

Euparkeria

Euparkeria was a small, Early Triassic, carnivorous animalfrom the Karoo basin of southern Africa. Its small fore limbs suggest it could run bipedally.

The Mesosaurus

Mesosaurus was a fresh-water dwelling reptile that livedfrom the late Carboniferous to the early Permian. It wasa lightly-built, four-legged animal with an elongated headand a flattened tail that was probably used for swimming. It was about 45 cm long. This carnivore probably ate fish and shrimp, catching them with its mouth. Mesosaurus was one of the first aquatic reptiles.

Diadectes (“Göðlar”) The diadectes were herbivorous reptiles,

approximately 2 m in length

Dinocephalian dynasty of the middle Permian

The Dinocephalians were among the most primitive of thetherapsids, "mammal-like reptiles". Some grew to huge size(5-6 meters) with meter long heads full of wicked teeth (the name Dinocephalian means "fearsome head"). These creatures succeeded the Pelycosaurs, being both larger in size and more metabolically active.

A Russian murderer

Titanophoneus was a dinocephalian reptile fromthe late Permian period of Russia. It's name means "giant murderer." Titanophoneus grew to a length of 3 m.

Late Permian reptilesThe Dinocephalians all died out suddenly at theend of the middle Permian. Why is not known. TheTherapsids that followed were smaller but moremammal-like. Some may even have had fur and warm-blood. These included the large Gorgon-opsians (the equivalent of the "saber-toothed tiger"), the small to medium-sized Therocephalia, and the peaceful herbivorous Dicynodonts.

Gorgonopsian Therocephalia Dicynodont

Therapsids - þelskriðdýrThe therapsids were a group of manydifferent species of reptiles, fromhuge plant-eaters with horns, thickskulls and sharp tusks for self-defense to large carnivores. Some were small as a rat, others big as a hippo. Even a lion-sized meat-eater with venomous fangs like a snake.

http://www.sunshine.net/www/2100/sn2192/therapsids.htm

The Therapsids (ca. 270 MY)The therapsids (þelskriðdýr), descendants of thepelycosaurs, developed physiology that was a step towards the mammals:

• Their legs were positioned more vertically beneath their bodies

• Their scull structure resembled that of mammals

• Their jaws were complex and their teth werediffrentiated into frontal incisors (for nipping), large lateral fangs (for puncturing and tearing) and molars for shearing and chopping food

Therapsid development

The Lycaenops (“Wolf Face”)It is believed that at least some of the therapsides, liketheir living mammal relatives, were endothermic, whichmeans they maintained a constant internal bodytemperature. Part of the reasoning for this is the lightand agile skeleton of this group. Such a build suggests an active animal. Also, the legs are rather long compared to the size of the body - far more so than in other contemporary animals. These long legs suggest they were capable of running, an activity that requires more energy.

TheProcynosuchus

“First dog crocodile”

One small, seemingly insignificant, otter-like therapsid —Procynosuchus — is thought to be the distant ancestor of the hot-blooded mammals. Fossil occurrance in South Africa and Germany

The large amphibian Eryopsemerging from a pool. The pelycosaurs Dimetrodon are in the rear.

Carboniferous amphibians andearly reptiles had jaws that couldsnap closed quickly, but couldapply little pressure. They hadpointed teeth that could kill prayquickly, but they were unable to slize or tear food apart. Whereas the alligator-like Eryptos had to swallow his meals whole, Dimetrodon could tear large animals to pieces...

The amfibians lost thePermian arms race

It was also a question of agility...

Neopteroplax, 290-260 MY amphibian fromthe late Carboniferous-early Permian

Reptiles like the Edaphosaurus andLycaenops were capable of greater speed than the amphibians

Late Permian Climate

Equatorial rainforest diminished as deserts spread across centralPangea. The southern ice sheets were gone, but an ice cap probably

covered the North Pole.

The dry Permian

Widespread evaporitesThroughout the Permian, largeparts of NW Europe wascovered by a very salty inlandsea, the Zechstein sea, whichadvanced and receded at leasttwice. This was home to animpoverished fauna, mainly brachiopods and bivalves, which were able to cope with the hypersaline conditions. Widespread accumulation ofevaporites, and more of Permian salt deposits than of any other age.

Permian evaporites on Svalbard...

...and in Texas

...in Germany...

Gypsum: a commonwhite or colorlessmineral (hydratedcalcium sulphate) used to makecements andplasters (especiallyplaster of Paris)

The Permian Mass Extinction- species affected -

The Permian mass extinction occurred about 248 millionyears ago and was the greatest mass extinction recordedin Earth´s history; larger than the Ordovician andDevonian crises and the better known K/T extinction at the end of the Cretaceous that felled the dinosaurs. 70-90% of marine species were eliminated as a result of thisPermian event. The primary marine and terrestrial victims included foraminifera, trilobites, rugose and tabulate corals, acanthodians, placoderms, and pelycosaurs, which did not survive beyond the Permian boundary. Other groups that were substantially reduced included the bryozoans, brachiopods, molluscs, ammonoids, sharks, bony fish, crinoids, therapsids.

Plants seem to have missed thegreat extinction. What floralchanges occurred during thePermian occurred earlier inthe period, when the gradualdrying out of the continent ledto the evolution and spread of better adapted "dry forms" such as gymnosperms and seed ferns to replace the swamp trees of the Carboniferous such as lycopods and sphenopsids. One major plant group disappeared, the swamp gymnosperm Cordaites. The mass extinction was primarily marine...

The PermianMass Extinction

- species little affected -

The Permian Mass Extinction- Causes -

The cause of the Permian mass extinction remains a debate, and numerous theories have been formulated to explain the events of the extinction:

• One of the most current theories for the mass extinction of the Permian is an agent that has been alsoheld responsible for the Ordovician and Devonian crises, glaciation on Gondwana, or possibly glaciation at high latitudes both north and south.

• Another theory which explainsthe mass extinctions of thePermian is the reduction of shallowcontinental shelves due to theformation of the super-continentPangea. Such a reduction in oceaniccontinental shelves would result inecological competition for space, perhaps acting as an agent for extinction. However, although this is a viable theory, the formation of Pangea and the ensuing destruction of the continental shelves occurred in the early and middle Permian, and mass extinction did not occur until the late Permian.

The PermianMass Extinction

- Causes -

The PermianMass

Extinction- Causes -

The third suggestion is that thePermian mass extinction occurred asa result of basaltic lava eruptions inSiberia. These volcanic eruptionswere large and sent a quantity of ashand sulphates into the atmosphere. Evidence in China supports thatthese volcanic eruptions may havebeen silica-rich, and thus explosive, a factor that would have produced large ash clouds around the world. The combination of sulphates in the atmosphere and the ejection of ash clouds may cooled the globe. The age of the lava flows falls within the interval in which the Permian mass extinction occurred.

The Siberian TrapsPresent coverageincluding associ-ated pyroclasticsis just under 2 million km2. Estimates of the original volume of the traps range from 1-4 million km3.

The eruptions lasted at full intensity for about a million years at the end of the Permian, which coincides with the extinction.

How could the eruptions cause extinction?

The Permian Mass Extinction - causes -

There have been speculations on a large meteoritecollision causing the mass extinction, but the this theory is not backed by comprehensive and convincing evidence. Possible impact site: off NW Australia

The fossil record of marine animal biodiversity

http://www.pbs.org/wgbh/evolution/library/03/2/l_032_03.html

Total extinction rates per million years

http://www.pbs.org/wgbh/evolution/library/03/2/image_pop/l_032_01.html

References, web-resources

• Stanley, Earth System History, chapter 15• Fortey, R. Life – A natural History of the first four billion years of life on Earth. New York, Vintage Books, 346 pp.• http://www.ucmp.berkeley.edu/permian/permian.html• http://hannover.park.org/Canada/Museum/extinction/permass.html• http://www.palaeos.com/Paleozoic/Permian/Permian.htm• http://palaeo.gly.bris.ac.uk/Palaeofiles/Permian/intro.html• http://jan.ucc.nau.edu/~rcb7/globaltext2.html• http://www.scotese.com/• http://www.pbs.org/wgbh/evolution/library/03/index.html• Skemmtileg videomynd: http://www.pbs.org/wgbh/evolution/library/03/2/quicktime/l_032_02.html• http://www.handprint.com/PS/GEO/geoevo.html#Perm• http://www.bbc.co.uk/education/darwin/exfiles/index.htm• http://www.science501.com/PTPermian.html• http://www.pbs.org/wgbh/evolution/library/03/2/image_pop/l_032_01.html •http://www.pbs.org/wgbh/evolution/library/03/2/l_032_03.html