The Cretaceous Period isGeologic AgeinmesozoicThe last period of the Phanerozoic Era began 145 million years ago and ended 66 million years ago. After 79 million years, it is the longest stage of the Phanerozoic Era[1][12]。
The Cretaceous was formed in 1822 byBelgiumgeologistJean d'Omalius d'Halloy StudyParis BasinProposed by.The Cretaceous Period is named for the stratum in western Europe during that period, which is mainly Cretaceous sedimentation.
Cretaceousjurassic periodandPaleogeneBC145 million years ago (error value is 4 million years) to 65 million years ago (error value is 300000 years).
The Cretaceous Tertiary extinction event isGeologic AgeThe most serious large-scaleExtinction eventOne is that most species, including dinosaurs, perished.The extinction event that took place at the end of the Cretaceous period becameCenozoic eraThe boundary of.
During the Cretaceous period,mainlandSeparated by the sea, the earth becomes warm and dry.
The Cretaceous is the largestdinosaurDuring the emergence period, many new dinosaur species began to appear, and dinosaurs still dominated the land,PterosaurGliding in the sky, hugemarine reptilesDominate the shallow sea.
The earliest snakes, moths, bees and many new small mammals also appeared.Angiosperms also appeared in this period.
The stratum formed during the Cretaceous period is called "Cretaceous System", abbreviated as KGerman(Kreidezeit).
Cretaceous atmosphereoxygenThe content is 150% today,carbon dioxideThe content isindustrial ageThe previous six times, the temperature is 4 ℃ higher than today.
The Cretaceous Tertiary extinction event isGeologic AgeThe most serious large-scaleExtinction eventOne is that most species, including dinosaurs, perished.
Like other ancient geological times, the Cretaceous rock marks are very obvious and clear, but the exact time of its beginning cannot be determined very accurately, and its error is within several million years.Not between Jurassic and CretaceousExtinction eventOr the characteristics of biological evolution can clearly separate two years.
The end of the Cretaceous period is relatively accurate, which ended between 65 million and 66 million years ago. At that time, the rock layers of the whole earth contain a large amount ofiridium。
This meteorite caused the extinction of a large number of creatures, which is called the Cretaceous Tertiary extinction event.However, this theory is still controversial.
Cretaceous sublayer
The early scientific literature divided the Cretaceous period into three periods, which are:Newcomb（Neocomian）、Gaulish（Gallic）、senonian （Senonian）。There are different opinions on how to determine the top and bottom boundaries of the Middle System.
From 1974 to 1982, there was a "Middle Cretaceous Event" organization in the world, which was very active, mainly studying the organisms in the Cretaceous periodstratigraphy、Transgression and regression, hypoxia eventGeomagnetic reversal, salt and chalk formation, South Atlantic andMozambiqueThe cracking of the canyon, andIndian Plate fromGondwanaAnd so on.
The middle Cretaceous is not an exact concept of geological age. Some people calculate from Aptian to Thornton, while most people calculate fromAlbuThe period starts from the Conniac period.
Division of Middle CretaceousMiddle EastIt is rarely used internationally.The Cretaceous dichotomy has been used for decades, and can be found in a large number of publications and geological maps, which is not suitable for further modification at present.
The Cretaceous system is divided into EuropeMarine strataOn the basis of the above, it was initially divided into 6~7 stages (stages) based on the ammonite standard. Later, some sub stages were upgraded to 12 stages (stages), but some people are still used to calling the 4 stages in the lower part of the Lower Cretaceous asNeocomian stage(or Neocomian).KangniakThorntonTogether with the three stages of Campan, they are called the Cenozoic Stage.Among the 12 stages, 53 ammonite belts can be divided, and planktonic foraminifera and calcareous nannofossils are used as important basis for Cretaceous stage division, zoning and intercontinental correlation.
The current scientific literature generally divides the Cretaceous period into the late and early periods, with a total of 12 periodsEuropeThe stratum of is named, which is subdivided from the latest to the earliest as follows:
Ⅲ.Barremian: 130.0 ± 1.5 – 125.0 ± 1.0 million years
Ⅳ.Hauterivian: 136.4 ± 2.0 – 130.0 ± 1.5 million years
Ⅴ.Fanlan current period: 140.2 ± 3.0 – 136.4 ± 2.0 million years
Ⅵ.Berian: 145.5 ± 4.0 – 140.2 ± 3.0 million years
formation
Announce
edit
The stratum formed during the Cretaceous period is called“Cretaceous system”, which can be crushed by hand. The abbreviation is K, which is the German abbreviation for Kreidezeit.
Cretaceous is not only developed in Europe, but also distributed in North America and western Australia.
Chalk islimestoneA type ofcalciteComposition, even and fine particles.The temperature in Cretaceous was about 4 ℃ higher than that today.
Geological structure
Announce
edit
North American scientists have abandoned the practice of some authors in the past to separate the Lower Cretaceous into "Komachi System" and adopted the international standard.
However, in the vast Rocky Mountains, the CretaceoustransgressionIt started from the late Early Cretaceous, and the early and middle sediments are generally absent.
1、 The lower part of the Cretaceous is famousWeldonGroup continental strata, includingHastings Layer and Weldon mudstone;
2、 The upper part of the Lower Cretaceous is a green sandstone layer, including the Aput and Albian deposits.
The Upper Cretaceous is a narrow sense of the Cretaceous, including the Cenomanian to early Campan strata, with the top missing the mid late Campan andMaastrichtStage sedimentation.
Japanese scholars believe that the Japanese islands are far away from Western Europe and belong to different regionsBiogeographic regionIt is difficult to directly compare with the international standard classification based on Europe. The marine Cretaceous system is divided into K1~K66 units independently, and different stratigraphic names are used in different facies regions.
The continental Cretaceous system is very developed in the hinterland of East Asia, rich in oilcoal, salt and other minerals, as well as various freshwater and terrestrial animal and plant fossils.
Only Tibet and Xinjiang in ChinaKashgarRegion, eastern Heilongjiang Province andTaiwan IslandOnly thenmarine faciesCretaceous sediments are developed to varying degrees in other vast areasContinental strata。
The eastern coast of China belongs to the circum Pacific active zone, which is sandwiched by red and variegated rock layersVolcaniclastic rockAnd lava;northwestInland basinMainly variegated sedimentary rocks;southwestAnd central China are mainly red rock formations.The lower part of the Lower Cretaceous in Northeast China is a coal bearing stratum, and the upper part isLacustrine deposit, clip a littleoil shale；The Upper Cretaceous is a famous oil-bearing rock series. Unlike North America, there are few coal bearing strata.
Cretaceous system in ChinaBiostratigraphySince the 1950s, great progress has been made in the research of, but the research foundation is relatively weak because it is mainly continental strata, and the regional formation and stage building work has not been completed so far, and the established layers in various regions cannot be compared with the marine standard layers perfectly.
Dinosaur Footprints of Cretaceous Period in Sichuan
The division of the Jurassic Cretaceous boundary has become a controversial issue for a long time, which seems to be difficult to be properly resolved in the short term.
Climatic environment
Announce
edit
CretaceousSea level changeLarge and warm climate, showing that a large area of land is covered by warm shallow sea.
The Cretaceous period is named after the common Cretaceous layer in Europe, but in other regions of the world, the Cretaceous stratum is mainly composed ofmarine faciesThese marine limestone layers are formed in a warm shallow sea environment.High sea level will cause a large range of subsidence, thus forming thickSedimentary layer。
Due to the thick Cretaceous stratum and its recent age, Cretaceous stratum outcrops are often found around the world.
The composition of chalk is common in Cretaceous strata.The chalk is marineCoccolith algaeIt is formed by deposition of calcareous shell particles (spherulite particles);Coccolith is a common algae in cretaceous period.
In northwest Europe, the Cretaceous sedimentary layer of Upper Cretaceous is often found, including:Dover White cliffs, Normandy coast, France, andLow land countries, Northern GermanyDenmarkcoast.The texture of chalk is not firm, so theseSedimentary layerThe texture is loose.These strata also include limestone and sandy rock.Sea urchinsArchery stone, ammonites, and marine reptiles (e.gMosasaurus）Fossil.
The Cretaceous strata in southern Europe are mostly marine strata, mainly composed of limestone and a few marls.During the Cretaceous period, the AlpsOrogenyIt hasn't happened yet, so the Cretaceous strata in southern Europe were mostlyTethysPerioceanicContinental shelf。
In the middle Cretaceous period, the flow in the lower layer of the ocean was slow, resulting in the anoxic environment of the ocean.
Many around the worldBlack shaleLayer, that is, the formation of anoxic environment during this period.These shale beds are important sources of oil and natural gas,the north seaSo it is.
Barremian periodThe climate ofjurassic periodThe last issue has already started.
High latitude areaThe snowfall ofthe triassic periodThe Jurassic period was more humid.However, glaciers only appear in high latitude mountains, whileLow latitudeSeasonal snowfall is still visible.
At the end of the Barremian Stage, the temperature began to rise and continued to the end of the Cretaceous.The reason for the temperature rise is the intensive volcanic eruption, which produces a large amount of carbon dioxide into the atmosphere.
Mid ocean ridgeMany thermal pillars have been formed along the line, causing the rise of sea level,Continental crustMany areas of are covered by shallow sea.Bit inequatorThe regional Tethys Ocean contributes to global warming.
stayAlaskaAndGreenlandDiscoveredPlant fossil, and discovered in the area of 15 ° south latitude since Cretaceousdinosaur fossil, which proves that the temperature in Cretaceous was quite warm.
The temperature gradient between the tropical region and the polar region is gentle, which may be due to the stagnation of ocean flow and the weakness of the planetary wind system.The widespread oil shale and anoxic events can confirm the stagnation of ocean flow.[2]
according toSedimentary layerAccording to the research ofsurface temperature About 42 ℃, higher than the current 17 ℃;The global average surface temperature of seawater is 37 ℃.The temperature of the ocean bottom is about 15 to 20 ℃ higher than our current temperature.[2]
Global land distribution during the Cretaceous period
Topographical features
Announce
edit
In the early Cretaceous,GondwanaIt has not been divided yet, and then South America, Antarctica and Australia separated from Africa, India andMadagascarIt is also connected to Africa.southAtlanticAnd the Indian Ocean began to appear.
The Tethys Ocean to the north of Africa is narrowing.Western Interior Seaway North America is divided into east and west parts, and this sea passage shrank in the late Cretaceous, leaving thickMarine depositLayer, including coal mine bed.
During the period of the highest sea level in the Cretaceous, 1/3 of the land on the surface was immersedYu HaiyangBelow.
The Cretaceous period is famous for its clay layer, which formed more thanPhanerozoicOther periods.The volcanic activity of the Mid Ocean Ridge, orSubmarine volcanoThe flow of nearby seawater makes the Cretaceous ocean rich in calcium and nearly saturated, which also makes the calcareousMicroplanktonThe number of.Widely distributed carbonate and othersSedimentary layerSo that there are many Cretaceous rock records.
From the late Cretaceous to the early Paleocene, large-scale volcanic eruptions occurred in IndiaDeccan Traps 。
During the Cretaceous, the rift between South America and the African continent rapidly opened to form the SouthAtlanticBy the end of the period, it had been widened to about 3000 kilometers.North AtlanticThe rift valley is located on the east side of Greenland and North AmericaNorth AmericaDrifting westward, the rift valley is expanding.Tethys SeaTo separate Eurasia from Africa, Central and Southern Europe andMiddle and Near EastMany countries intransgressionMedium.
In Cretaceous, the climate was relatively warm, and nopolar regionEvidence of ice cover.At that time, most areas had abundant rainfall and humid climate, and offshore and coastal areas were rich in oilcoal, natural gas and oil shale deposits, such asTexas, MexicoPersian Gulf, North Africa and Russiaoil field, like ChinaSongliao PlainUpper CretaceousDaqing Oilfield , many large coalfields of the Lower Cretaceous in Northeast China and Inner Mongolia.In some areas with arid and hot climate, such as the Southwest Lake Group andYun-mengLakes Water system, with huge thickness of gypsum salt deposit deposits.In addition, in the Cretaceous red beds in Yunnan, copper bearing placer deposits are famous in China for their high grade, large scale, easy mining and smeltingTongxiang。
Species distribution
Announce
edit
Cretaceous: the golden age of dinosaurs (painted by Zhao Chuang)
Gymnosperms andFernIt still occupies the dominant position, pine and cypressCycasGinkgo biloba, pteridophyte and arthropod constitute the main flora.
Angiosperms began to appear inEarly Cretaceous, increased significantly in the middle periodTerrestrial plantDominant in China, beechbanyan, magnolia, maple, oak, poplar, camphor, walnutplane treeEtc. have appeared, approaching the Cenozoic eraFloraThe face of.
Since JurassicNannofossilIts characteristics change with different horizons, which has important stratigraphic significancePebbleIn addition, there are extinctMicroconeStone（Nannoconus）Wedge stone（Sphenolithus）Etc.
PreJurassicSclerodermacoverBony fishReplaced by.oceaninvertebrateThe emergence of mesoplankton foraminifera has become an important basis for the division and correlation of the middle and late Cretaceous marine strata, and many benthic macroforaminifera also appearStandard fossil。Chrysanthemum stone and archery stone evolve rapidly and obviously, and are widely distributed. They are standard fossils for traditional classification of stages and zones.
Gregarious benthicFixed clamRudistids can form reefs, which are typical warm water fauna, and are found in the Upper Cretaceous strata of Tibet and southern Xinjiang in China.Sea urchins thrive in the Tethys Sea, with a few standard species.Coral andBrachiopodsIn Cretaceous, it was in a secondary position.
Freshwater invertebrates are also abundant, such as crustaceans, ostracods andLeaf acrosomeRapid evolution, molluscs, snails and mussels are widely distributed, as well as insects and freshwaterCharophyte fossil, many of them can be classified and contrastedContinental strataThe standard fossil ofGeological mappingPlays an important role in the exploration of mineral resources such as oil and coal.
Early Cretaceous in ChinaPhytogeographyThe division is very obvious. According to the research on spores and pollen, there are at least two distinctPalynoflora。
（1） Seamless Dicystic Powders – Leptorhabdosporium（Disacciatrileti-Cicatricosisporites）Flora.It is distributed in the northern region, mainly including northeast and northern North China.There are luxuriant plants here, especially PinaceaePodocarpineandSeagold sandFamilies and other plants form rich coal reserves.It also means it's warm and humid hereClimatic zone。
（2） Classot powder – Cyperus fern spore（Clas-sopollis-Schizaeoisporites）Flora.It is distributed in the southern region, and mainly produces red strata containing gypsum salt deposits, reflecting the relatively hot and dryClimatic environment。Between 40 ° and 50 ° north latitude, there is a strip transition zone in the direction of NWW SEFloraMixed phenomenon occurs.From the perspective of global distribution, the situation of South and North China flora is similar to that of arid zone and humid subtropical zone.
Botany
Early CretaceousGymnospermsThe main plant community is still flourishing, andangiospermThe appearance ofPlant evolutionAnother important event in history.
The Cretaceous has a reliableEarly angiospermIn the late Late Cretaceous, angiosperms flourished rapidly, replacing the dominant position of gymnosperms and forming an angiospermous flora that continues today, such asa magnolia, Liu, Fengpoplar, birch, palm, etc.
The emergence and development of angiosperms are not onlyFloraThis is a great change in the world, and it also has a great impact on animals.Angiosperms are some animals, such as insects, birdsMammals, providing a large amount of food to enable them to breed;On the other hand, the role of animals in spreading pollen and seeds also contributes to the prosperity and development of angiosperms.
The flowering plants (angiosperms) began to appear and spread in the Cretaceous, but it was not until the Campanian terrace that they became the dominant plants.The appearance of bees is conducive to the evolution of flowering plants, and flowering plants and insects are examples of coevolution.At the same time, banyanplane tree, magnolia and other large plants began to appear.
Some early gymnosperms still exist, such asPine cypress。Araucaria lanceolataWith other pines and cypresses thriving and widely distributedBenecydidesPerished at the end of the Cretaceous.
In the Early Cretaceous, the cycadsCycas benneiClass, ginkgo, pine and cypress,Filicinae Still thriving.
Geoangiosperms, which rose in the late Early Cretaceous, developed rapidly in the Late Cretaceous and gradually replaced gymnosperms as the dominant species.Angiosperms appeared at the beginning of this period and gradually developed later.Chrysanthemum, dinosaur, pterosaur, ichthyosaur, plesiosaur, etc. have gradually become extinct from prosperity, and mammals and birds have become emerging animal groups.
Terrestrial fauna
The Cretaceous dinosaur species reached its peak. At this time, the most famous dinosaur wasTyrannosaurus RexAt that time, the huge and fierce reptiles in the sea were no less than Tyrannosaurus rex, among which the pliosaurs and marine creatures of mixed dragonslizardThe Cang dragon of the same species can be more than 15 meters long, which is more than the reverse halberd we knowwhaleandgreat white sharkAll are big.[3]
The thick shell clam, which was used to build reefs in the Cretaceous ocean, reached its peak and once replaced coral as the main reef building organism, making modernCoral reefIt has been interrupted for nearly 70 million years.By the end of the Cretaceous period about 67 million years ago, a large number of these marine and terrestrial animals had been extinct, with only a few remaining.[3]
Many prevailing and dominant categories in the Mesozoic era, such asGymnosperms, reptiles, ammonites, archery stones, etc., which declined or disappeared in the later period, emerging angiosperms, birds, mammalsGastropods、BivalveThe development of the new biological evolution stage indicates the arrival of the Cenozoic era.Reptiles in vertebrates reached their peak from the late Jurassic to the early Cretaceous, representingTyrannosaurus rex、Pterosaur、Qingdao DragonAnd then went into decline.
At the end of the Cretaceous period, dinosaurs, ammonites and other biological groups were largely extinct.There are many controversies about the cause of this mass extinction of living things.
Some people think it is a giant in the universemeteorThe reason is that the content of iridium in clay rocks on the boundary between Cretaceous and Tertiary is abnormally high.
Velociraptor
In the animal kingdom, mammals are still relatively small, only a small part of land animals.Dominant animals on land are stillMain dragonsReptiles, especially dinosaurs, are more diversified than in the previous period.
PterosauridaIt flourished in the middle to late Cretaceous, but gradually faced the competition of radiation adaptation of birds.At the end of Cretaceous, there were only about two families of pterosaurs.[4]
Birds are the most successful group of vertebrates that develop into the air.Birds began to differentiate in the early Cretaceous, and their flight ability and arboreal ability were more thanarchaeopteryxGreatly improved.The famous“Confuciusornis ”Is a representative member of birds in the Early Cretaceous.[4]
At the end of the Cretaceous, life on the earth experienced another major extinction event: a large number of reptiles that dominated the earth's surface disappeared, and dinosaurs were completely extinct;More than half of plants and othersTerrestrial animalIt also disappears.What exactly caused the sudden extinction of dinosaurs and a large number of creatures?This problem has always been a puzzle in geological history.It is generally accepted thatMeteorite impact theory。Remarkably, mammals were the biggest beneficiaries of this extinction event. They survived the crisis and occupied the ecological environment withdrawn by dinosaurs and other reptiles in the subsequent Cenozoic, rapidly evolving into new rulers on the earth.A large number of early Cretaceous small dinosaurs, birds and mammals have been found in the Chaomidianzi Formation in Liaoning Province, China.Many kinds found hereManiraptor, regarded as the connection between dinosaurs and birds, including severalFeathered dinosaurs 。
Insects began to diversify at this time, and the oldest ants, termites, lepidoptera (butterflies and moths) were found.Budwormgrasshopper、Gall waspIt also began to appear.
AmmoniteHaving a straight shell, belonging toAsteraceae, and reef building organismsClamBoth are prosperous animals of the sea.Twilight BirdsIt is a group of primitive birds that cannot fly and can swim in the water, just like the modern grebe.ForaminiferaGlobotruncanidae andEchinoderma(e.gSea urchin、Starfish）Continue to live.In the Cretaceous, the earliestdiatom(It should be siliceous diatom rather than calcareous diatom);Diatoms living in fresh water did not appear until Miocene.For causingBiological erosionCretaceous is an important stage in the evolution of these species.
Extinction event
Announce
edit
Violentcrustal movementThe changes of sea and land led to the great changes of the Cretaceous biosphere. Many popular and dominant categories of Mesozoic (such as gymnosperms, reptiles, ammonites and archery stones) declined and disappeared in the later period, and emerging angiosperms, birds, mammals, gastropods, bivalves, etc. all developed, indicating a new stage of biological evolution - the advent of the Cenozoic era.[5]
Reptiles reached their peak from the late Jurassic to the early Cretaceous, and continued to occupy the sea, land and air.Birds continue to evolve, and their characteristics are constantly approaching modern birds.Mammals have developed slightlyMarsupialAnd primitive placentalEutheria 。Fish have been completelyEuosteichthyesMainly.
The most important phylum of marine invertebrates in the Cretaceous is still the class of ammonites. The ammonites are far more diverse in shell size, shell shape, shell decoration and suture type than those in the Jurassic.During the Cretaceous, the southern ancient continent continued to disintegrate, and the northern ancient continent continued to rise. The climate became cold and seasonal changes were obvious.The omnivorous, insectivorous and scavenger animals survived the extinction event, probably because their feeding habits changed a lot.There seems to be no complete herbivorous or carnivorous mammals at the end of the Cretaceous.Mammals and birds rely on insectsearthworm、snailThey live in K-T events while they feed on dead plants and animals.Scientists assume that these creatures live on organic detritus, so they canFloraThe collapse of the extinction event survived.
Atlas of Cretaceous Animals
In the riverBiomeOnly a few animals perished;Because the river biological community mostly depends on the biological organic debris washed down from the land, and less on living plants directly.The sea has a similar situation, but it is more complex.Animals living in the planktonic zone are far more affected than those living in theseabedOur animals are still big.Animals living in the planktonic zone almost live on living phytoplankton, while animals living on the seabed feed on organic detritus of organisms, or can be converted into organic detritus of organisms.
Among the creatures that survived this extinction event, the largest land animals arecrocodileAndLyosaurus, is a semi aquatic animal, and canBioclasticMake a living.Modern crocodiles can live on decay, and can not eat for months;Juvenile crocodiles are small in size and slow in growth. In the first few years, they feed on invertebrates and dead creatures.These characteristics may be the key for crocodiles to survive the extinction event at the end of Cretaceous.
The Cretaceous was an era of rapid changes in the distribution of the earth's land and the biosphere, rapid cracking of the Atlantic Ocean and frequent volcanic activities, and extensive transgression occurred in the late low-lying terrain.Late CretaceousangiospermReplacing gymnosperms on land is a major change in the plant world.The animal kingdom changed significantly at the end of the Cretaceous, including dinosaurs, ammonites and many othersbiological groupMass extinction indicates that the Cenozoic Era is about to begin.The cause of this mass extinction has been hotly debated in the international scientific community.The popular theory of "extraterrestrial events" believes that in some places on the earth, there is an abnormally high content of iridium in clay rocks on the Cretaceous Tertiary boundary, which is similar to that produced by a giant meteor colliding with the earth in the universeNuclear winterAccording to the effect, when the Cretaceous Tertiary boundary is determined around the world,Iridium anomalyIs an important principle.However, there are also many people who have doubts and objections to the "extraterrestrial event". They believe that the mass extinction of living things at the end of the Cretaceous was gradual and was the result of ecological changes, rather than a disaster caused by a simple collision of extraterrestrial visitors with the earth.
Cretaceous(English:Cretaceous Period）YesGeologic AgeThe last period of the Mesozoic Era, 70 million years long, wasPhanerozoicThe longest stage of.
In the west, the strata of this age are mainlyCretaceousIt is named after sedimentation.The Cretaceous period is between Jurassic and Paleogene, from 137 million years ago (error value of 4 million years) to 65 million years ago (error value of 300000 years).Cretaceous-TertiaryThe extinction event is one of the most serious mass extinction events in the geological age, and most species, including dinosaurs, perished.
Like other ancient geological times, the Cretaceous rock marks are very obvious and clear, but the exact time of its beginning cannot be determined very accurately, and its error is within several million years.There is no extinction event or biological evolution between Jurassic and Cretaceous, and two ages can be clearly separated.The end time of the Cretaceous period is relatively accurate, which is about 65.5 million years ago (some scientists estimated it to be 65.9 million years ago). At that time, the rock layers of the whole earth contained a large amount of iridium.It is generally believed that a huge meteorite hit the earth at that time, and there was a big crater near the Yucatan Peninsula in Mexico today.This meteorite caused a lot ofExtinction, calledCretaceous Tertiary extinction event。But this theory is controversial.[6]
Paleontological discovery
Announce
edit
On September 15, 2014,Zigong Dinosaur Museum With experts from China University of Geosciences, we conducted a field study on the dinosaur footprints found in Xinyang and Longjing villages in Dashi Township, Xuyong County, Luzhou City, and concluded that there were three kinds of dinosaur footprints in the Cretaceous period, about 100 million years ago.
In 2022, the staff of Zhucheng Dinosaur Culture Research Center in Shandong Province found a relatively complete water ripple trace fossil and some large dinosaur footprint fossils in the main fossil heritage areas of Zhucheng in the spring during the field fossil survey.The geological and geomorphic development and preservation of this fossil relic area are relatively complete. Through the comparative analysis of the surrounding rock stratum sedimentation and the characteristics of the strata and strata around the fossil relic site, it is preliminarily determined as the Early Cretaceous geologystratum.[8]
In January 2022, the Cretaceous fish fossils more than 100 million years ago were found in Linhai, Taizhou. The largest fossil is a whole lifelike fish.[9]
Research progress
Announce
edit
Cretaceous Red Clam Fossils[13]
In March 2020, a new study in the Journal of Paleooceanography and Paleoclimatology of the American Geographic Society said that mollusc shell fossils in the late Cretaceous revealed a secret:The age of dinosaursAt the end of the day, the earth rotates faster than it does today. The earth rotates 372 times a year, compared with 365 times at present.This means that one day in the Cretaceous lasted only 23 and a half hours.[7]
In August 2023, during the investigation of paleontological fossils carried out by Bayannur Institute of Paleontological Fossils Protection and Institute of Vertebrate Paleontology and Paleoanthropology of Chinese Academy of Sciences, the staff found a Cretaceous lizard in Bayinmanduhu Dinosaur Fossil Reserve of Urad Back BannerFossil lizard skulls.[10]
In October 2023, the "Peak Mission" Zooyoufengke Archaeological Biology TeamIn the late Cretaceous strata 70 million years ago, the scientific research team found abnormal ammonites, describing that some biological groups had genetic disorder before the fifth mass extinction.[11]
