No.ofQuestions:2OKTOEFLiBTCompletePracticeTest

TPO29WritingSection1

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readingYouhave3minutestoreadthepassage.Clicktobeginreadingnow.LargenumbersofdinosaurfossilshavebeendiscoveredindepositsonAlaskasNorthSlope,aregionthattodayexperiencesanextremelycold,arcticclimate.Onehundredmillionyearsago,whenthosedinosaurswerealive,theenvironmentoftheNorthSlopewasalreadyinhospitable,especiallyduringthewinterwhenitexperiencedseveralmonthsoftotaldarkness.Howdidthedinosaurssurvivethewintertime?PaleontologistshaveproposedthatoneofthemostcommonNorthSlopedinosaurs,theelephant-sizededmontosaur(Edmontosaurus),survivedthewinterbymigratingsouthtomorehospitableregions.Severalargumentssupportthemigrationhypothesis.First,theedmontosaursdietsupportsthemigrationhypothesis.Edmontosaursfedexclusivelyonplants.SincetherewouldhavebeennoplantsgrowingduringthecoldanddarkNorthSlopewinter,itappearsthattheedmontosaurmusthaveleftforatleastpartoftheyearandmigratedtomoretemperatezonestofindfood.Second,manyedmontosaurskeletonshavebeenunearthedfromthesamesite.Thissuggeststhatedmontosaurslivedinherd.Manymodern-daymigratoryanimals,suchascaribouandbuffalo,liveandmigrateinherdsaswell.Movinginherdshelpsanimalscoordinatetheirmigration.Thefindingthatedmonotsaurslivedinherdsfurthersupportsthemigrationhypothesis.Finally,edmonosaurswerephysicallycapableofmigratinglongdistances.Toreachmorehospitableregions,theedmontosaurhadtomigrateabout1,600kilometerssouthward.Tomakesuchajourney,theedmontosaurneededtomoveataboutfivekilometersperhourforseveralweeks,whichiscertainlycoulddo.Theseanimalscouldrunveryfast,reachingspeedsupto45kilometersperhour.Itcouldhaveeasilyuseditsotivepowertomovetowarmerclimateduringtheharsharcticwinters.V2