Sorted

Ages and subdivisions

The beginning of Sorted is defined today officially by UNESCO in Meishan in China by the appearance of the Conodonte Hindeodus parvus .

Sorted is subddivisé in 3 times (Lower Triassic, average and higher) and in 7 stratigraphic stages :

Paleogeography and tectonic evolution

Since the Carboniferous higher and closing on its western part of a vast East-West ocean called Paléotéthys, the major part of the emerged grounds is gathered in only one supercontinent called Pangée. Thus with Lower Triassic, the ground resembles a kind of " CAP-Man " with the open mouth towards the east. The " machoire" higher is called Laurasia, the lower part Gondwana and it bathes in a vast ocean called Panthalassa (all sea). Paléotéthys (the ocean which thus forms space in the mouth) continues to be closed again in the east during all Sorted it. Its closing by subduction in direction of north creates a succession of small oceans (called basins of back-arc) which one observes today the sediments mainly in Eastern Europe (basins known as of Hallstatt, Meliata, Maliak and Küre). With the Permian , certain grounds separated from the northern margin of Gondwana and started to derive towards north. They are parts of the Turkey, Iran, Afghanistan, Tibet and China of the South. This chain of large islands is called unintermitting Cimmériens; they will enter in collision ave Laurasia to Sorted higher generating the Orogénèse cimmérienne. Sorted higher also sees developing an important province Magma tick which recovers today the Morocco and the New England in the United States. This volcanicity is precusor of the opening of the central Atlantique which will follow.

If thus Sorted it is remarkable for its calm tectonics in Western Europe and in particular in France, its history in the east of the austro-Switzerland border is rather agitated. It is also in the mountains between the the Tyrol and China of the south, that one will find the most important deposits of Sorted and where its modern stratigraphy was defined.

Climate

Lower Triassic in Western Europe is marked by important deposits of rocks evaporitic S. the principal mines of salt of Switzerland (Mines of Bex), of Austria (Hallstatt), of Germany and from Lorraine come from triassic sedimentary deposits. Moreover any glacial sediment is not known with Sorted. They are thus signs of a hot climate which will perdurera for all the period. The important size of supercontinent Panga was to moderate the influence of the ocean on its climate and there was to be large deserts as well as important zones of continental Climat.

Evolution of the life

Sorted begin with definition after the greatest extinction from alive species in the history from the evolution from the life on ground, that of the Permien limit/Trias. Sorted ends in another of the 5 greater extinctions. Between these two reference marks Nets, Lower Triassic it is marked by slow and difficult rediversification of the species after the catastrophe. It is as probable as the still unstable environment caused several small extinctions which marked stops in the rediversification. Sorted average is one stable time which observes the return of complete and complex ecological systems, in particular the reefs which were absent from Lower Triassic. Sorted higher is marked by a succession of small crises touching each time various communities (fauna Benthique, fauna pelagic, terrestrial flora, the Dinosaures), crises intersecting with the periods of stability and which will bring to the great crisis of the limit Trias/Jurassic.

Three types of organizations thus mark Sorted it: survivors of the Limit Permian/Sorted (P/T), of the groups which will explode but which will have one limited lifespan and of the new groups which will dominate all the Mesozoic . In detail:

Maritime environment is marked by the establishment with Sorted average modern types of corals after the extinction of the forms Paléozoïque S in extreme cases Permien/Trias. A type of algae limestones (tubiphytes) will also create important reefs but this group will die out almost completely during Sorted higher. The Ammonites go rediversifier and to become again abundant starting from one only surviving line of limit P/T. pelagic Bivalves will be also locally very abundant. The Conodonte S, important group for the dating of the rocks, will die out completely in extreme cases Sort-Jurassic. The fish, which underwent few losses in extreme cases P/T, show a great stability. The marine reptiles (in particular the Ichthyosaure S, Plésiosaure S, Placodonte S) will develop, to become common to Sorted average and to reach enormous sizes with Sorted higher. The principal change in the oceans will be the appearance with Sorted higher Plancton with shells limestones and nanoplancton. This appearance will modify deeply as well ecology and the oceanic food chain as marine chemistry.

Over ground, the survivors of limit P/T who are the Lycophyte S still dominate with Lower Triassic before leaving their place to the cycade S, Ginkgophyta (which are represented more currently only by Ginkgo biloba ) and the glossoptéride S. Then the Spermatophyte S, or plants with seeds will dominate the flora and in the northern hemisphere the coniferous will multiply.

Various groups of Amphibians will follow one another throughout Sorted while being maintained successfully. In the reptiles, the Archosaures gradually will replace the reptiles Synapside S which dominated the Permian one. In Carnien, Cynodonte S will give rise to the first mammals. At the same time, the Ornithodira, which were a not very significant group with species of small sizes, will evolve to the Ptérosaure S and part of the Dinosaure S. the Lepidosauria (snakes and lizards) appears in Carnien, in fact more precisely the Sphenodontia count today only two species in danger of extinction in some islands of New Zealand. The first tortoises will appear in Norien.

See too

geological Time scale
Sorted, a kind of Orchidée S

External bonds

Objective-Ground, Sorted it

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Simple: Triassic

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