Dinosaurs(Greek:δεινόσαυρος,deinosauros)werethedominantterrestrialvertebrateanimalsforover160millionyears,fromthelateTriassicperiod,about230millionyearsago(Ma),untiltheendoftheCretaceousperiod,about65Ma,whenmostofthembecameextinctintheCretaceous–Tertiaryextinctionevent.ThefossilrecordindicatesthatbirdsevolvedfromtheropoddinosaursduringtheJurassicperiod,andmostpaleontologistsregardthemastheonlycladeofdinosaurstohavesurviveduntilthepresentday. 　　Dinosaurswereavariedgroupofanimals.Paleontologistshaveidentifiedover500distinctgeneraandmorethan1,000differentspeciesofdinosaur,andremainshavebeenfoundoneverycontinentonEarth.Somedinosaurswereherbivorous,otherscarnivorous.Somewerebipedal,othersquadrupedal,andotherswereabletoshiftbetweenthesebodypostures.Manyspeciesdevelopedelaborateskeletalmodificationssuchasbonyarmor,hornsorcrests.Althoughgenerallyknownfortheirlargesize,manydinosaurswerehuman-sizedorevensmaller.Mostmajorgroupsofdinosaursareknowntohavebuiltnestsandlaideggs,suggestinganoviparitysimilartothatofmodernbirds. 　　Theterm"dinosaur"wascoinedin1842bySirRichardOwenandderivesfromGreekδεινός(deinos)"terrible,powerful,wondrous"+σαῦρος(sauros)"lizard".Throughthefirsthalfofthe20thcentury,mostofthescientificcommunitybelieveddinosaurstohavebeensluggish,unintelligentcold-bloodedanimals.Mostresearchconductedsincethe1970s,however,hassupportedwhathassincebecomethescientificconsensusview:thatdinosaurswereactiveanimalswithelevatedmetabolismsandnumerousadaptationsforsocialinteraction. 　　Sincethefirstdinosaurfossilswererecognizedintheearlynineteenthcentury,mounteddinosaurskeletonshavebecomemajorattractionsatmuseumsaroundtheworld.Dinosaurshavebecomeapartofworldcultureandremainconsistentlypopular.Theyhavebeenfeaturedinbest-sellingbooksandfilmssuchasJurassicPark,andnewdiscoveriesareregularlycoveredbythemedia.Asaresult,theword"dinosaur"hasenteredthecommonvernacular,althoughitsuseandmeaningincolloquialspeechmaybeinconsistentwithmodernscience.InEnglish,forexample,"dinosaur"iscommonlyusedtodescribeanythingthatisimpracticallylarge,slow-moving,obsolete,orboundforextinction.