Mesozoic | U.S. Geological Survey

Mesozoic (252-66 million years ago) means 'middle life' and this is the time of the dinosaurs. This era includes the Triassic, Jurassic, and Cretaceous ... Skiptomaincontent Officialwebsitesuse.gov A.govwebsitebelongstoanofficialgovernmentorganizationintheUnitedStates. Secure.govwebsitesuseHTTPS Alock()orhttps://meansyou’vesafelyconnectedtothe.govwebsite.Sharesensitiveinformationonlyonofficial,securewebsites. Label Close US.GeologicalSurvey Science Products News Connect About LatestEarthquakes WebChat Share  Facebook  Twitter  Linkedin  Digg  Reddit  Pinterest  Email Breadcrumb YouthandEducationinScience Mesozoic ByYouthandEducationinScience YouthandEducationinScience Mesozoic(252-66millionyearsago)means'middlelife' andthisisthetimeofthedinosaurs. ThiseraincludestheTriassic,Jurassic,andCretaceousPeriods,namesthatmaybefamiliartoyou.Itendedwithamassivemeteoriteimpactthatcausedamassextinction,wipingoutthedinosaursandupto80%of lifeonEarth.  Mesozoicsignpostsarecolored blue. TheimagesshowtheartontheTrekThroughTimesignposts.ThenameofeachperiodisalinktotheentireplaqueinstalledontheTrekThroughTime. TheTriassicPeriod:252to201millionyearsago WhatdidEarthlooklikeduringtheTriassicPeriod? Sources/Usage:PublicDomain. Artist'srenditionoflifeintheTriassic.Notetheplatemovementsalsointhelowerleftoftheseimages.  AlthoughthesupercontinentPangaeaexistedthroughouttheTriassic,theforcesthatformeditimmediatelybegantopullitapart. Pangaeabegantorotatewithdifferentplatesrotatingindifferentdirectionsatdifferentrates. Theresultingtensioncausedaseriesofripsinthecontinent,andtheEarthsaggeddownintotheseripsformingriftbasins. DuringtheTriassic,theseriftbasins(orriftvalleys)developedbetweenNorthAmericaandEuropeandbetweenAfricaandSouthAmerica. WithcontinuedseparationthroughouttheJurassicPeriod,thesebasinsbecametheAtlanticOceanandtheGulfofMexico. OtherriftslatersplitoffAntarctica,India,andAustralia. WhatwasEarth’sclimatelikeduringtheTriassicPeriod? TheclimateduringmuchoftheTriassicwaswarmwithadrycontinentalinteriorandnoevidenceoficeatthepoles. WhatanimalswereonEarthduringtheTriassicPeriod? AfterthegreatextinctionattheendofthePermian,manynewkindsofanimalsevolvedduringtheTriassic. Thedominantlandanimalswerereptiles. Thefirstdinosaurs,marinereptiles,lizards,andtortoisesappeared.  MammalsappearedduringtheTriassic,buttheyremainedinsignificantuntiltheircompetitors,thedinosaurs,becameextinctattheendoftheCretaceous. Crocodileswereabundant.Itwasinthisperiodthatinsectsattainedcompletemetamorphosis. WhatplantswereonEarthduringtheTriassicPeriod? Therewereclimaticvariationsduetoalternatingwet/dryandcold/hotseasonsthatinfluencedthedistributionofplantcommunities. Conifers,cycads,andfernswerecommon.   TheJurassicPeriod:201to145millionyearsago WhatdidEarthlooklikeduringtheJurassicPeriod? Sources/Usage:PublicDomain. Artist'srenditionofJurassiclife.Largereptilesdominatedtheland,andbirdsappear. ThebreakupofPangaeathatbeganintheTriassiccontinued,andtheearlyAtlanticOceanandtheGulfofMexicoappearedasshallowcontinentalseas. ShallowinlandseascoveredpartsofthewesternUnitedStates. WhatwasEarth’sclimatelikeduringtheJurassicPeriod? Warmtropicalgreenhouseconditionsoccurredworldwide. WhatanimalswereonEarthduringtheJurassicPeriod? Giantplant-eatingdinosaursroamedtheEarthwithsmallerbutviciouscarnivoresstalkingthem. Flyingreptilesandthefirstbirdsappeared. Creepingaboutintheundergrowthweretinymammalsnobiggerthanrats. Theshallowoceanscontainedabundantlifefromtinyplanktontohuge,whale-sizedmarinereptiles. WhatplantswereonEarthduringtheJurassicPeriod? Coniferscontinuedtobethemostdiverselargetrees. Cycads(evergreen,cone-bearing,palm-likeplants)becamesoabundantanddiversethattheJurassicissometimescalledthe"AgeofCycads." WhatwasVirginialikeduringtheJurassicPeriod? AstheAtlanticOceanopened,east-flowingriverssuchastheJamesandtheRoanokedeveloped. Alongtheriftvalleys,volcanoeswereactive. WhatwasVirginialikeduringtheJurassicPeriod? ThesesedimentsarepresentassandstonesandshalesinVAtoday.   TheCretaceousPeriod:145to66millionyearsago WhatdidEarthlooklikeduringtheCretaceousPeriod? Sources/Usage:PublicDomain. Artist'srenditionoflifeintheCretaceous.Mostofthesespecieswillnotsurvivethemassextinctionattheendofthisperiod.NotethatthesupercontinentPangeaisbreakingapart.  TheAtlanticOceancontinuedtolengthenandwiden,particularlytothesouth,whichsplitSouthAmericafromAfrica. Indiaseparatedandbecameanislandcontinent. Muchofeachcontinentwascoveredwithshallowcontinentaloceansandinlandseas. NorthAmerica,Europe,Asia,andAfricabecameaseriesofislands.  ThepartoftheUSbetweentheRockyMountainsandtheAppalachiansandOzarkswasmostlyunderwater. WhatwasEarth’sclimatelike? DuringtheLateCretaceous,withrisingsealevelsandseparatedcontinents,shallowoceancurrentscarriedwarmwaterfarthertowardthepoles. Thiscreatedamildglobalclimatewithice-freepoles. WhatanimalswereonEarthduringtheCretaceousPeriod? Atleastinitially,dinosaursandmarinereptilescontinuedtoflourish,andmanynewspeciesappeared. Birdsdiversifiedandexpandedinnumbers,andtheymayhavebeenthereasonthatflyingreptilesdecreasedsignificantly. Thereweremanynewmammals,includingthethreegroupsthatlivetoday. Duetotheappearanceoffloweringplants,manymoderngroupsofinsectsappearedandbegantodiversify,includingants,termites,bees,butterflies,aphids,andgrasshoppers. WhatplantswereonEarthduringtheCretaceousPeriod? OneofthemostsignificantdevelopmentsduringtheCretaceouswastheappearanceandrapiddiversificationofthefirstfloweringplants. WhatwasVirginialikeduringtheCretaceousPeriod? Ashallowsea,partoftheearlyAtlanticOcean,coveredeasternVirginia. WhatelsehappenedduringtheCretaceousPeriod? AlargemeteoritecrashedintotheGulfofMexico66millionyearsago,causingamassivetsunamiandaclimatedisruptionthatkilledupto80%oftheworld'sanimalandplantspecies,thelastofthedinosaursbeingthemostnoticeablevictims. ThismassextinctioneventseparatestheMesozoicfromtheCenozoicEra. OnwardtotheCenozoic! BackwardtothePaleozoic BackwardtotheIntroduction