ocean animals have been getting bigger 阅读理解答案

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1、Oceananimalshavebeengettingbigger阅读理解答案　　Oceananimalshavebeengettingbiggeroverthelasthalf-billionyears.Notalittlebigger.Notevenalotbigger.Theyhavemushroomedgigantically,scientistsnowconclude.　　Theirnewfindinglendssupportforsomethingknownas“Cope’srule.”

2、Itholdsthatanimalstendtoevolveintospeciesthataremuchlargerthantheirdistantancestors.Thishypothesis(假说)takesitsnamefromthe19thcenturypaleontologistEdwardDrinkerCope.Whilestudyingfossils(化石),hewasthefirsttonoticethistrend.　　NoelHeimisapaleontologistatSta

3、nfordUniversityinPaloAlto,Calif.Healsoisaco-authorofthenewstudy.HisteamcomparedthebodysizeofanimalsbetweentheCambrianPeriodandmoderntimes.Thiswasaspanof542millionyears.Theanimalsstudiedincludedspeciesfrommorethan17,000genera.Theyrangedfromancienttrilob

4、ites,plesiosaurs(extinctreptileswithalongneckandflippers)andmanylessfamiliarcreaturestotoday’swhalesandclams.　　Oceananimalstodayareanaverageof150timeslargerthantheywereduringtheCambrian,Heim’sgroupreports.Thesmallestanimalsalivetoday—tinycrustaceanscal

5、ledostracods—areonlyaboutone-tenththesizeoftheCambrian’stiniestanimals.Buttoday’slargestoceananimals—whales—aremorethan100,000timesbiggerthanthebiggestintheCambrian.　　“Classesofanimalsthatwerealreadybig…tendedtolivelonger,”Heimsays.Theyalsotendedtochan

6、gemorethanclassesofanimalsthatweresmalldid.　　Thesizegainsinoceananimalsaremuchlargerthanwouldbeexpectedbychance,saysJonathanPayne.He’saco-authorwhoalsoworksatStanford.　　Thescientistsdon’tknowwhatdrivesthetrend.Onepossibilityisanarmsrace(军备竞赛)betweenpre

7、datorsandprey.Theideahereisthatlargeranimalsarelesslikelytobecomesomeotheranimals’meal.Anotherpossibilityhastodowithoxygen.Landanimalsevolvedfromspeciesthatstartedintheocean.Someoftheselandanimalseventuallyreturnedtotheocean.Andtheykepttheabilitytobrea

8、theoxygen-richair.Thatmayhavemadeiteasierforthemtooutgrowanimalsthathadtofilter(过滤)theiroxygenoutofthewater.　　Whatcurrentanimalsmaybestillustrate“mushroomed”inparagraphone　　A.Plesiosaurs.B.Ostracods.C.Whales.D.AfricanElephants.　　60.What