ByAliceBryant

31July

ACanadianscientistmighthavefoundtheearliestevidenceofanimallifeonEarth.

GeologistElizabethTurnerpresentedherfindingsinthesciencepublicationNatureinlateJuly.

ThisundatedphotoprovidedbyElizabethTurnershowsafieldlocationinNorthwestTerritories,Canada.CanadiangeologistElizabethTurnermayhavefoundtheearliestfossilrecordofanimallifeonEarthinthearea.(CourtesyofElizabethTurner/LaurentianUniversityviaAP)

TurnermadeherdiscoveryintherocksofCanadasNorthwestTerritories.Shehasbeendoingresearchtheresincethes.Theareawheresheworkshashighmountainsandcanonlybereachedbyhelicopter.Butanestimatedmillionyearsago,theareawasunderthesea.

There,Turnersaidshefoundtheremainsofspongespreservedasmineralsinrock.Therockcontainsstructuresthatlooklikemodernspongesthatliveintheworldsoceans.

JoachimReitnerisanexpertonspongesatGermanysUniversityofG#;ttingen.Reitnerwasnotinvolvedintheresearch.Butheagreedthefindingsmustbeakindofsponge.

Datingofrocklevelssuggeststhattherockscontainingthestructuresareaboutmillionyearsold.Thatwouldmakethemaboutmillionyearsolderthantheoldestspongefossilsfoundduringearlierstudies.

PacoCardenasisanexpertonspongesatSwedensUppsalaUniversityandwasnotinvolvedintheresearch.Hesaidthedateofthespongeisthemostshockingthingaboutit.Discoveringspongefossilsfromclosetomillionyearsagowillimproveourunderstandingofearlyanimallife,hesaid.

Manyscientistsbelievethefirstanimalgroupsincludedspongesorsponge-likecreatureswithoutmusclesornerves.Buttheyhadotherqualitiesofsimpleanimals,includingcellsfordifferentpurposesandspermforreproduction.

However,thereisverylittlescientificagreementaboutthingsthathappenedonebillionyearsago.SootherresearcherswillcontinuetoexamineanddebateTurnersfindings.

"Ithinkshesgotaprettystrongcase.Ithinkthisisveryworthyofpublishing.Itputstheevidenceoutthereforotherpeopletoconsider,"saidDavidBottjer.HeisapaleobiologistatUniversityofSouthernCaliforniaandwasnotinvolvedintheresearch.

ScientistsbelievelifeonEarthappeared3.7billionyearsago.Theearliestanimalsappearedmuchlaterbutexactlywhenisstilldebated.

Theoldestundisputedfossilspongesdatetoaroundmillionyearsago,atimecalledtheCambrianperiod.

Somescientistsusingamethodcalledthemolecularclocksayevidencesuggestsspongesappearedaroundabillionyearsago.Themolecularclockmethoddateschangesinlivingthingsbasedontheideathatgeneticchangetakesplaceataregularrateoverlongperiodsoftime.

Butnosupportingphysicalevidenceforthefirstappearanceofspongeshadbeenfound.

"ThiswouldbethefirsttimethataspongefossilhasbeenfoundfrombeforetheCambrian,andnotonlybefore,butwaybefore—thatswhatsmostexciting,"saidCardenas.Headdedthattheresearchseemstoconfirmthemolecularclockestimates.

LittlefossilevidenceexistsbeforetheCambrianperiod,whenanimalsfirstdevelopedhardbones,exoskeletonsandshells.Thosestructuresaremorelikelytobepreserved.

Thetimeperiodofmillionyearsagoisimportant.Iftheorganismisconfirmedasasponge,thediscoverywouldprovethatthefirstanimalsdevelopedbeforeoxygenreachedalevelscientiststhoughtwasneededforanimallife.Butrecentresearchsuggeststhatsomespongescansurvivewithlittleoxygen.

"EverythingonEarthhasanancestor,"saidRogerSummons.HeisanMITgeobiologistwhoalsowasnotinvolvedintheresearch.Hesaidithasalwaysbeenpredictedthatthefirstproofofanimallifewouldbesmallandmysterious.

ImAliceBryant.

TheAssociatedPressreportedthisstory.AliceBryantadapteditforLearningEnglish.MarioRitter,Jr.wastheeditor.

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sponge–n.akindofseaanimalthatlivesincoloniesandformshardstructuresinthewater

geologist–n.ascientistswhostudiestherockstolearnaboutthehistoryoftheEarthanditslife

fossil–n.theremainsofancientplantsoranimalsthathavebe