Jurassic is aGeologic Age, bounded bythe triassic periodandCretaceousBetween 199600000 BC (error value is 600000 years) and 145500000 BC (error value is 4 million years).Jurassic ismesozoicThe second period ofTriassic Jurassic extinction event。Although the rock marks of this period are very obvious and clear, the exact time of its beginning and end, like other ancient geological ages, cannot be determined very accurately.
The name of Jurassic Period comes fromSwitzerlandFrench borderJura Mountain(Modern translationRula Mountain）, French paleontologistA. BrowniarIt was proposed in 1829.Because the Jurassic lithology in Europe has obvious trichotomy, in 1837, L.vonBuchThe Jurassic in southern Germany is divided into lower, middle and upper parts.In 1843, F.A. Kunstede called the lower black marlstone Black Jurassic and the middle brown iron bearing limestoneBrown jura, upper white marlBaijura。Jurassic is divided into early, middle and late periods.
In the early Jurassic period, due to the mass extinction, all kinds of animals and plants are rare (belonging to the stage of recuperation), butDinosaurOne branch stands out, waiting for the opportunity to dominate the land.After the middle and late Jurassic period,dinosaurIt will become the most prosperous dominant species on the earth and will rule the earth for 150 million years untilCretaceous Tertiary extinction eventuntil.
During the Middle and Late Jurassic, plate movement caused the southern part of South America to separate from Africa.Laoya Ancient LandIt also gradually separated from Africa and South America, creating the Atlantic Ocean and the Gulf of Mexico.Along the margins of these rift continents, volcanic activity is frequent.At the same time, Eurasia moved southward, narrowing the Tethys Ocean.With the rise of sea level in Jurassic period, sea lanes on the continental margin were formed between North America and Europe.
In the Jurassic period, there were more independent landmasses on the earth than in the Triassic period, leading to the increase of coastal zones.
During the whole Jurassic period, most of them were warm and humid.The flourishing forest vegetation at that time formed the rich coal resources in Australia and Antarctica today.Although there were some arid areas at that time, the vast majority of Pangea was in lush oases.The biota of Laua continent and Gondwana continent in the south are still very unique in many aspects, and the fauna has more intercontinental colors.
Jurassic is aGeological age, between Triassic andCretaceousBC199600000 years ago (error value is 600000 years) to 145.5 million years ago (error value is 4 million years)mesozoicThe second period ofTriassic Jurassic extinction event。Although the rock marks of this period are very obvious and clear, the exact time of its beginning and end, like other ancient geological ages, cannot be determined very accurately.
Jurassic dinosaur
The Jurassic was formed byAlessandre Bloniar(Alexandre Brongniart)SwitzerlandBorderlineJura MountainThere are many large-scalemarine facieslimestoneOutcrop.The Chinese name originates from the old Japanese useJapanese Kanji PronunciationIts transliteration name is "Jurassic" (pronunciation: シュラキキ, Roman word: shuraki).
the triassic periodSome of the most primitive mammals in the late stagelate jurassic It is on the verge of extinction.Other early types of mammals were newly produced in the Early Jurassic——Gnarled mammal, which is considered to be the type of plant feedingCenozoic eraEarly extinction.The paleomammals in the Middle Jurassic are generally considered asMarsupialAnd ancestors of placental mammals.
Cartilaginous SclerodermaClass began to decline in Jurassic and wasWhole bone fishReplace.The earliestEuosteichthyesIt was not until the late Jurassic that there was a great development, with an increase in number but a small number of species.
Marine behemoths in the Jurassic period
The Jurassic ammonites are more evolved, mainly manifested in the complexity of sutures, and the increasingly diversified shell decorations and shapes, which may be due to the adaptation of ammonites to different marine environments and various lifestyles.Jurassicmarine faciesBivalveIt is very rich. Non marine bivalves have also developed rapidlyContinental strataIt plays an important role in the division and comparison of.
Jurassic isGymnospermsThe heyday of.CycasClass and ginkgo reached a peak,ConifersIt also occupies a very important position.
Stratigraphic division
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marine faciesJurassic stratum is rich inFossil, especiallyAmmonitesObvious features and complete preservation.On this basis, in 1815, W. Smith of England put forward the idea of using paleontological fossils to divide and correlate strata.In 1842, AC. Dobini proposed a smallerChronostratigraphic unitAnd named most of the Jurassic stages.German in 1856A. OpelA more detailed division of ammonite belt is proposed.Jurassic strata are officially divided into 3 series, 11 stages and 74 ammonite belts.Lower Jurassic（Lias series）It is divided into Hetang Stage, Sinemurian StagePrinsbachianAnd Torian;Middle Jurassic(Daoge Series) is divided into Alinian Stage, Bajou Stage, Batong Stage and Karolinian Stage;upper jurassic (Mam series) is divided into Oxford stage, Kimurian stage and Tetanian stage (Volga stage).The detailed ammonite zoning provides a good basis for the division and correlation of marine Jurassic in the world.staymarine faciesThe division of Jurassic top boundary and series has not been unified internationally.Jurassic strata in ChinaContinental depositMainly.becauseTerrestrial organismThe evolution speed and distribution breadth are not as fast asAmmonitesTherefore, the research accuracy of continental Jurassic is relatively low.[1]
Major events
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Some obvious geological and biological events occurred in Jurassic.maximumtransgressionThe event occurred inLate JurassicLate Cretaceous, andUnited Ancient LandThe splitting coincides with the new ocean expansion rate enhancement event.Circum Pacific beltOfNevada MovementIt also occurred in the late Tertiary, which may indicate that the united ancient land strengthened and split with the ancient landPacific plate There is some relationship between the accelerated subduction events.From the late Kimuri period, the Tethys region and the northern region were obviously separated from the marine animals, reflecting thatPaleoclimatic zonationandPaleogeographic isolationThe degree of strengthening.The cooling events at the end of Middle Jurassic are reflected in many parts of Eurasia.Rareiridium、OsmiumSome people think that the anomaly is the result of small extraterrestrial stars hitting the Earth.
Climatic minerals
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At this time, the climate around the world is very warm. The ocean generated by pouring into the crack generates humid wind, and the inland desert brings rainfall.Plant extends to the pastGlabrousIt provides food for dinosaurs (including the largest land animals) with a wide distribution and a large number.The earliest small birds flying over them;These birds may have evolved from small dinosaurs.The ocean is composed of large, swimming new reptiles and modernTeleost fishShared by.
The climate is warmer and more uniform than modern times, but there are also differences between tropical, subtropical and temperate zones.Early and Middle Jurassic, represented by evaporite and eolian sand duneArid climateThe belt appears in the south of North AmericaSouth AmericaAnd Africa,late jurassic It extended to central and southern Asia at that time.South China was in a tropical subtropical humid climate in the early Jurassic, and gradually became hot and dry in the middle and late Jurassic;In northern China, the climate was warm and humid in the Early and Middle Jurassic, and the warm and humid areas in the Late Jurassic shrunk.Strong Tectonic Changes in the Circum Pacific Belt and the Circum Pacific PlateContinental plateIs closely related to subduction.Withtectonic movementThe intensity ofMagmatic activityForming tungstentinMolybdenum, lead, zinc, copper, iron and other minerals have become the main part of the Pacific metal metallogenic belt.[2]
Biological overview
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The age of dinosaurs
Jurassic isdinosaurThe heyday ofthe triassic periodThe dinosaurs that appeared and began to develop have quickly become the rulers of the earth.All kinds of dinosaurs come together to form a world of dragons in various shapes.At that time, except for the huge body on landapatosaurus , Liang Longbrachiosaurus Etc, underwaterichthyosaurAnd flyingPterosaurAnd so on.[3]
Terrestrial life
majorHerbivorousvertebrateyesProtosauropodsandOrnithopteraDinosaurs, and similarMammalsSmall reptiles.But in the late period, the hugeSauropodsDinosaurs are in the ascendant.These animals can eat high and low plants at the same time;Dragonfoot mainly grinds food by swallowing stones.
Largetheropods Herbivorous animals;Small theropods, such asCoelophysis Class andCompsognathus Class and others hunt small prey and may also eat carrion.
The insects in Jurassic were more diversified, and more than 1000 kinds of insects lived in forests, lakesswampNearby.Except the existingcockroach、dragonflyClassbeetleBesides class, there areGrubClasswoodlice Class, flies and borers.Most of these insects have survived to modern times.
Botany
Chilean pineThe coniferous forest, a close relative ofTree fernPalm likeCycasLarge layer forest composed of Cycads and Cycads.The ground is covered with dense vegetation composed of ferns and horsetails.
In the Jurassic plant community,GymnospermsCycads, conifers and ginkgo in the.Extremely prosperous.FernInEquisetum、Filicinae And dense pine, cypress, ginkgo and arborFern toothThe grass ferns and other grasses are all over the low places, covering the ground.Cycads and ferns grow in relatively dry areas, forming vast evergreen fields.Before the Jurassic, the plant division on the earth was relatively obvious. Due to migration and evolutionFloraThe climate of Jurassic period is generally similar.
Aerial creatures
Leather wingedPterosaurClass is the dominant creature in the air.Early birds also appeared, the most famous beingarchaeopteryx, owned and smalltheropods Similar bones, teeth and claws, but also have feathered wings and tail, and can fly.Air creatures and ground creatures will also evolve.[3]
birds
The emergence of birds represents another important event in the evolution of vertebrates.1861 in Bavaria, GermanySorenhofenArchaeopteryx fossils found in the late Jurassic strata are recognized as the oldest representative birds;Found by Chinese paleontologists in Liaoning“Sinosauropteryx(Sinosauropteryx) fossils have received extensive attention from the international academic communityFeatherThe origin and evolution of birds provide new important materials.With the emergence of birds, vertebrates occupied the three ecological fields of land, sea and air for the first time.[3]
Living things in water
dinosaur
PseudodragonsandPlate toothed dragonAll species are extinct, butichthyosaurThe animals living in the shallow sea and a group of sea where the limbs have evolved into fin shaped limbs survivedCrocodilia And bony fish.othermarine organismalsoPlesiosaurAnd short dragons.In the late period, ichthyosaurs and sea crocodiles gradually declined.[4]
