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-中国的古生物学家希望解释出动物的起源

2021-01-05 

本文摘要:AMONG the mysteries of evolution, oneofthemostprofoundiswhatexactlyhappenedatthebeginningofthecambrianperiod.beforethatperiod which started 541 myearsagoandranonfon lifewasamodestthing.bacteriahadbeenaroundforabout3billion years,butformostofthistimetheyhadtheearthtothemselves.seaweeds,Jeaweeds spongesandtheoddwormdostarttoputinanappearanceafewmillionyearsbeforethecambrianbegins.butredintoothandclawtheprecambrianwa snoo 寒武纪以前(即5.41亿年前,倒数5600万年)的物种很少。

AMONG the mysteries of evolution, oneofthemostprofoundiswhatexactlyhappenedatthebeginningofthecambrianperiod.beforethatperiod which started 541 myearsagoandranonfon lifewasamodestthing.bacteriahadbeenaroundforabout3billion years,butformostofthistimetheyhadtheearthtothemselves.seaweeds,Jeaweeds spongesandtheoddwormdostarttoputinanappearanceafewmillionyearsbeforethecambrianbegins.butredintoothandclawtheprecambrianwa snoo 寒武纪以前(即5.41亿年前,倒数5600万年)的物种很少。细菌已经出现了30亿年,在这期间地球只伴随着它们。在寒武纪到来的数百万年前,海草、水母类、海绵和鬼蚯蚓开始出现。

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但是红牙利爪生物直到寒武纪都没有经常出现。Then,in the 20m-yearblinkofageologicaleye,animalsarrivedinforce.mostofthemaingroupsoftheanimalkingdom-arth room coelenterates molluscs and even chordate s, thebranchfromwhichvertebrateswentontodevelop-arefoundinthefossilbedsofthecambrian.thesuddenevolutionofthismegafaunaisk thecams uriesafteritwasnoticed,inthemountainsofwalesafterwhichthecambrianperiodisnamed,nobood人们在寒武纪化石床上找到了动物王国的主要动物集合。也包括腕足、腔肠、棘皮、软体、脊索(脊椎动物进化的分支)。

寒武因越来越激烈和巨大动物群的急剧进化而闻名。在被发现的2世纪后,在以寒武纪命名的威尔士山,没有人知道为什么越来越激烈。A group of Chinese scientists,ledbyzhumaoyanofthenanjinginstituteofgeologyandpalaeontology, plantochangethatwithaprojectcalled“fromthesnowballearthtothecambrianexplosion : theevolutionoflifeandenvironment 600 myearr“ toaseriesoficeagesthathappenedbetween 725 mand 541 m years ago.these were,at their maxima amongthemostextensiveglaciationsintheearth’ though是, withperiodsthatmakethemoderntropicsseemchilly : the planet’saveragetemperaturewassometimesashighas 50c.addthefact nti nent (viewedfromtheearth’s south pole ) wasbreakingupatthistime, andyouhaveapictureofaworldinchaos.justthesortofthingthatmightdriveevolution.drzhuandhiscolleagueshopetofindoutexactlyhaos thes respondtochangesinthefossilrecord .中国科学家团队——是朱茂炎派的南京地质古生物所,“从冰雪地球到寒武愈: 6亿年前的生命进化与环境“冰雪地球”再次发生在7.25亿年至5.41亿年前这些时期的高峰是地球历史上冰川运动最普遍的时期。冰川活动在这些时期交错再次发生,现代热带地区看起来很冷,但地球的平均温度有时不会下降约50。

并且可以想象超强大陆(上图右图,位于南极附近)在这个时期分化,那时的世界会多么恐慌。只有一些物种不会进化。朱博士和他的同事们希望这些环境变化能准确地找到与化石记录相对应的变化。the animals’carnival动物狂欢节Fortunately, China’sfossilrecordforthisperiodisrich.until recently, theonlyknownfossilsofprecambriananimalswerewhatiscalledtheediacaranfauna-ahandfulofstrangecreaturesfoundinaustralia, canadaandtheenglishmidlandsthatlivedintheediacaranperiod,between 635m and 541m years ago是andwhichbearlittleresemblancetowhatcames however,a team led by Chen Junyuan,also of the Nanjing institute andanotherledbyxiaoshuhaiofthevirginiapolytechnicinstitute, in America是discovered a 580 m-year-oldlagerstte-aplacewherefossilsareparticularlywellpreserved-inageologicalformationcalled幸直到最近,人们发现的唯一前寒武纪的动物化石被称为埃迪卡拉动物群——在澳大利亚、加拿大、英国内陆发现的住在埃迪卡拉纪期(6.35亿年到5.41亿年之间)的奇怪生物,它们与后来的生物一点也相似但是,1998年,南京地质古生物所陈均远队和美国弗吉尼亚理工大学带着肖书海队,找到了另一个5.8亿年前的寒武纪宝库,该地化石留下比较好,被称为陡山沱两组地层,产于中国南部地区。

Portents of the modern world现代世界的前兆thislagersttehasyieldedmanypreviouslyunknownspecies, including microscopic sponges表示smalltubularorganismsofunknownnature, thingsthatlooklikejellyfishbutmightnotbeandarangeofwhatappeartobeembryosthatshowbilateralsymmetry (pictured right ) . whattheseembryoswouldhavegrownintoisunclear.butsomemightbetheancestorsofthecambrianmegafauna .这个化石宝库发现了很多不为人知的物种。另外,还包括微海绵动物。目前还不知道这些胚胎会进化。

但是,可能是寒武纪巨大动物群的祖先。totrytolinktheevolutionofthesespecieswithchangesintheenvironment是chuxueleioftheinstituteofgeologyandgeophysicsinbeijingandhii havefoundthattheproportionofc-alightisotopeofcarbonthatismoreeasilyincorporatedbylivingorganismsintoorganicmatterthanitsheee c c-increasedonatleastthreeoccasionsduringtheediacaranperiod.theysuggesttheseincreasesmarkmomentswhentheamountofoxygenin ent up, becausemoreoxygenwouldmeanmoreoxidisationofburiedorganicmatter.thatwouldliberateitsc,forincorporationintoroccess他们已经在有机体中他们指出,这些快速增长记录了海水中氧的减少量,因为更好的氧意味着更好的有机化合物的水解。它释放碳12,与岩石融合。eachofdrchu’soxidationeventscorrespondswithanincreaseinthesize,complexity and diversity of life是bothplantandanimal.whattrigggee is unclear.theremayhavebeenanincreaseinphotosynthesisbecausethereweremorealgaearound.orerodedmaterialfromnewlyformedmound haver uldotherwisehavereactedwithoxygen,leading to a build-up of the gas .楚博士的水解活动都是植物和动物的生命形状、复杂性,但启动时的原因依然是个谜。

由于周围的藻类变多,光合作用有可能减少。或者从新构成的山体生锈的材料在消化有机化合物时不吸入氧,构成气体。the last-andmostdramatic-riseinoxygentookplacetowardstheendoftheediacaran.follow-upworkbydrzhu是innineothersectionsofthedou suggeststhissurgestartedjustafterthefinalprecambrianglacialperiodabout 560 my earrs andwentonfor9myears.thesedatesoverlapwiththoss nrocksinotherpartsoftheworld是confirmingthatwhateverwasgoingonaffectedtheentireplanet.drzhususpectsthisglobalenvironmentalshi博士对陡山沱两组地质层的其他9个部分进行了研究,指出氧的减少正好发生在5.6亿年前的前寒武纪冰河期,持续了约900万年前。这些日期正好与世界其他地区发现的岩石水解迹象一致,证实再次发生的一切都影响了整个地球。

朱博士庞加莱的全球环境变化促进了简单的动物进化。drzhualsoplanstopushbackbeforetheediacaranperiod.otherresearchershavefoundfossilsofalgaeandwormlikecreaturesinrocksinnnorther her hemarinoanglaciation,635m years ago, whichmarkstheboundarybetweentheediacaranandthecryogenianperiodthatprecedesit.(thecryogenianbegan 850 m years ago.) such fossils are sodrzhuwillusenewimagingtechnologiesthatcanlookatthemwithouthavingtocleanawaythesurroundingrock andarealsoabletodetecttracesoff 其他研究者已经在中国北部地区的岩石中发现了水藻化石和蚯蚓类生物,在6.35亿年前的冰川世纪末,显示了埃迪卡拉纪和成冰系时代的边界后腿。

(出冰系始于8亿5千万年前。由于这样的化石很难研究,朱博士需要使用新的图像工程来观察它们,需要能准确地观察化石周围的岩石,用肉眼寻找有机化合物化石的足迹。besidesdiggingbackbeforetheediacaran是the new project’sresearchersalsointendtoanalysetheunfoldingofthecambrianexplosionitselfbb hasseveralthatdatefromthecambrian.dr Chen,indeed,first made his name in 1984, whenheexcavatedoneatchengjianginyunnanprovince.itdatesfrom 525 m years ago是which make it 20 myearsolderthanthemostfamouscambrianlage theburgesshaleofbritishcolumbia是in Canada.the project’sresearchersplantoseehow,evolutionarily speaking,thevariouslagerstet totrytodetermineexactlywhendifferentgroupsoforganismsemerged .除了发掘埃迪卡拉纪以前的项目外,新项目的研究者们还发现了其他化石宝库(中国有来自寒武纪的化石陈博士最早于1984年对云南省澄江生物群进行了实地调查而闻名。

云南澄江生物群情的愤怒起源于5.25年前,比西方最有名的寒武纪化石宝库“不列颠哥伦比亚州伯吉斯生物群”(加拿大)早了2000万年。项目的研究者们试图告诉我们不同的化石宝库和其他有什么联系,正确确认不同的有机生物集团经常出现的时间。theywillalsolookatthechemistryofelementsotherthancarbonandoxygen-particularlynitrogenandphosphorous, whichareessentialther and sulphur, whichoftenindicatestheabsenceofoxygenandisthusantitheticaltomuchanimallife.drzhuhopestomapchangesinthedistributionoftheseccc m hewillassesshowthesechangescorrelate,whethertheyarerelatedtoweathering,mountainbuildingandtheebbbandflowofglaciers, howtheycouldhaveaffectedtheevolutionoflife,andhowplantsandanimalsmightthemselveshavealteredthechemistryofairandsea .他们也将碳和氧硫指出缺氧会危害大部分动物。

朱博士期待着能绘制这些化学元素在时间和空间上的生产变化图。他还估计这些变化如何相互关联,它们与风化、山体建设和冰川潮汐有关,它们如何影响生命的进化,植物和动物如何改变空气和海洋的化学成分。Most ambitiously,Dr Zhu, drxiaoandtheircolleagueshopetodrillrightthroughseveralfossiliferoussitesinsouthernchinawhereediacaranrocksturnseamlesslyintoca arevaluablebecauseinmostpartsoftheworldthereisagap、known as an unconformity、 betweentheediacaranandthecambrian.unconformitiesareplaceswhererockshavebeenerodedbeforenewonesaredeposited, andthewidespreadediacaran-cambrianunconformityhasbeenabigobstacletounderstandingthecambrianexplosion.with luck, then amysteryfirstnoticedinthewelshmountainsintheearly 19 thcenturywillbesolvedinthechineseonesintheearly 21st.if itis, theoriginoftheanimalkingdomwillhavebecomeclear,andanimportantgapinthehistoryofhumanityitselfwillhavebeenfilled .朱博士世界上大部分的这个不统一面的岩石在新岩石产生前就生锈了,不统一面广泛分布在埃迪格拉纪-寒武纪之间,它们对寒武的研究越来越严重的阻碍。

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幸运的是,19世纪初在威尔士山脉发现的第一个秘密是回答21世纪中国人想表达的问题。确实,动物王国的起源逐渐明确,填补了人类历史上最重要的差距。


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