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雅思阅读机经：GeneralTrainingBPterosaurs.docx

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雅思阅读机经：GeneralTrainingBPterosaursAPterosaursstandoutasoneofnature'sgreatsuccessstories.TheyfirstappearedduringtheTriassicperiod,215millionyearsago,andthrivedfor150millionyearsbeforebecomingextinctattheendoftheCretaceousperiod.Uncontestedintheair,pterosaurscolonizedallcontinentsandevolvedintoavastarrayofshapesandsizes.BUntilrecently,mostscientistswouldnothaveputpterosaursinthesameclassasbirdsintermsofflyingability.Becausepterosaurswerereptiles,generationsofresearchersimaginedthatthosecreaturesmusthavebooncold-blooded,likemodernsnakesandlizards.Thiswouldhavemadeflyingawkward,astheywouldhavelackedtheendurancetopowertheirmusclesforlongperiodsoftime.CInthepastthreedecades,however,anumberoffossildiscoverieshavepromptedresearcherstore-examinetheirviews.Thenewpictureofpterosaursrevealsthattheywereunlikeanymodernreptile.FromafossildiscoveredinKazakhstan,scientistssuspectthatpterosaurshadacoveringresemblingfur.Ifso,thisdetailprovidesevidenceofawarm-bloodedbodythatcouldmaintainthekindofeffortneededtostayintheair.Indeed,scientistsnowbelievethatmanypterosaursweregiftedair?bornepredators,builttofeedwhileinflight.And,infact,suchcontroversyhassurroundedpterosaurssincethefirstdiscoveryofoneintheearly1700s.DCosimoAlessandroCollini,thefirstnaturalhistoriantostudythefossilanddescribeit,wasunabletoclassifyit.Itwasnotuntil1791thatthegreatFrenchanatomistGeorgesCuvierdeducedthattheanimalwasinfactaflyingreptile,whosefourthfingersupportedawing.HonamedthefossilPterodactylus,combiningtheGreekwordsforwingandfinger.Afewdecadeslater,thenamepterosaur,orwingedreptile,wasadoptedtodescribethegrowinglistofsimilarfossils.EIn1873,aremarkablepterosaurspecimencametolightthatconfirmedCuvier'sdeduction.Unlikeearlierfossils,thisnewfindneartheBavariantownofSolnhofencontaineddelicatewingimpressions,establishingdefinitelythattheextinctreptilewascapableofflight.Eventhoughoverathousandpterosaurspecimensareknowntoday,suchwingimpressionsremainrare.NormallyonlybonessurvivethefossilizationprocessFButhowpterosaurslear