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Missing link is found between egg and adult of earliest known animals

By Eddie Weaver,2014-12-15 04:19
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Missing link is found between egg and adult of earliest known animals

Missing link is found between egg and adult

    of earliest known animals

    WCH

    Paleontology

    Missinglinkisfoundbetweeneggand adultofearliestknownanimals A篓磊

    Thefindingswerereportedinthe naloftheGeologicalSocietyof VirginiaInstituteofTechnology, College,andZHOUChuanmingand traitsincommonwithboth

    groups?

    Whiletherearethou-

    sandsofearlY-stage

    embryos,accordingtothe

    article,only80havebeen

    recoveredthathavead-

    vancedtoanintermediary

    stageofdevelopment.The

    latterhaveanenvelope

    simartothatofearlier

    embryonicstage,andeach

    ofthemhasacoiledtubu-

    larembryowithinthe

    envelope.Theirenvelope

    hasagrooveonthesurface,

consistingofthreeclock-

    wisecoils.Using

    microfocusX?-raycorn?-

    PutedtomograPhY

    (microCT)imaging,thesci-

    entistsvirtuallypeeledoff

    theenvelopeandexposed

    theembryoinside.Thetu-

    bularembryoisalsowound

    into.withthreeclockwise

    shownarescanningelectronphotomicrographsof twofossiIembryospecimensfromthe600-miIIion? yeaoldDoushantuoFormationinSouthChina.The soccer_baII-shapedspecimenisinterpretedasanearly staqefblastuIa)embryo,andthebasebaIl-shaped specimenisinterPretedasanintermediate-stage heIicaIembryoCOnSistingofthreeclockwisecofIs. EachembryousedtobeencIosedinanenveIope, whichwasremoved(somepiecestremainsinthe

    soccebalI.shapedspecimen)sothattheembryo itseIfisexPosed.Embryosareabout0.550.75

    miIIimeterindiameter.(Credit:ShuhaiXiao) coils.Insomespecimens,thescien-

    tistsfoundsignsofuncoiling."This

    isfurtherevidencethattheseembryos

    wouldhavegrownintothetubular

    organisms,"Xiaosaid.

    Inthearticle,theresearchers

    state,"ifthispossibilityholdsupto

    furthertesting,thenewfossilsmay

    bridgethedevelopmentalgapbe? tweentwopreviouslydescribed Doushantuoforn'ls.''

    "Thediscoveryofadditionaljnter- mediarystagesandevenmoread- vancedspecimenswouldbetheulti- matetest,"Xiaosays.Butthecondi- tionsthatpreservedtheancientembryos maynothavebeenfavorableforpre- servingorfossilizingmoredeveloped lifeforms,theresearchersnote.Con- nectingthefirstmomentsofanimal evolutionwilllikelyrequiremoreuse ofadvancedimagingtechniques.?

    BulletinoftheChineseAcademyofSciencesI79

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