最新研究验证：现代鸟类的起源可追溯到恐龙时代
Anewstudyprovidesevidencesuggestingthattheevolutionofmodernbirdscommencedlongbeforetheextinctionofdinosaurs./VCG
鸟类是当今世界上物种多样性最高的陆生脊椎动物，现生种类约1.1万种，其起源和演化此前普遍被认为发生在恐龙灭绝之后，也有猜想认为起源于恐龙时代。近期由中美科学家联合开展的一项基因组学研究用新的证据验证了这一观点：现代鸟类的起源可以追溯到恐龙时代。
该研究由江苏师范大学伍少远教授研究团队、中国科学院古脊椎动物与古人类研究所周忠和院士与来自美国哈佛大学、佐治亚大学等机构院所的科学家共同完成，研究成果日前在线发表于国际学术期刊《美国国家科学院院刊》。
研究人员从124种鸟类基因组序列中提取到25640个不同遗传位点的DNA序列数据，结合不同地质历史时期的化石记录，通过系统进化树构建、分子钟演化时间估算、物种多样性分化速率等分析，重建了现代鸟类的演化历史和轨迹。
在涵盖了近95%现代鸟类物种多样性的新鸟小纲中，研究人员发现了一支全新的鸟类进化谱系，并将其定名为水陆鸟类，包含了水鸟及其近缘种类。水陆鸟类与早期研究发现的陆鸟类一起构成了新鸟小纲的两大谱系。
Anewstudyprovidesevidencesuggestingthattheevolutionofmodernbirdscommencedmuchearlierthanpreviouslybelieved,predatingtheextinctionofdinosaurs.
PublishedearlierthismonthinthejournalProceedingsoftheNationalAcademyofSciences,thestudywasledbyscientistsfromChinaandtheUnitedStateswhoanalyzedthegenomesof124livingbirdspeciesandcreatedanevolutionarytreeforNeoaves,whichinclude95percentofallmodernbirds.
Combiningfossilrecords,theyfoundthatthemainlineagesofbirdscanbedividedintotwogroups,withonegrouprepresentingland-basedspeciesandtheothergrouprepresentingwaterbirds.TheyestimatedthatthissplittookplaceduringtheLateCretaceousperiod(roughly87millionyearsago),longbeforetheend-Cretaceousextinctioneventthatwipedoutdinosaursapproximately66millionyearsago.
Thefindingschallengethewidely-heldbeliefthatthedinosaurianextinctionwasfollowedbyarapidevolutionofbirdspecies.Previousstudiesindicatedthatthecatastropheresultedintheeliminationofbirds'competitionforresources,therebyfacilitatingtheirfastdiversificationintothe11,000speciesweseetoday.
Theextinctionevent"seemstohavehadalimitedimpactonbirds'evolution,"saidfirstauthorWuShaoyuan,aprofessorfromtheJiangsuNormalUniversityineastChina.
Researcherswhoworkedonthestudyalsofoundthataglobalwarmingeventoccurring55millionyearsagowasresponsiblefortheevolutionofmodernseabirdspecies,suchaspenguinsandseagulls.
Thenewfindingsprovideamorecomprehensiveandrefinedperspectiveontheevolutionofbirds,saidco-authorZhouZhonghe,fromtheInstituteofVertebratePaleontologyandPaleoanthropology,theChineseAcademyofSciences.
"Thedevelopmentofmodernbirds,unlikethepreviouslyacknowledgedpatternofrapidevolutionarychanges,isagradualandcontinuousprocessdrivenbynaturalselection.Theytendtoalignwiththediversificationofplants,mammals,fishandinsects,"Zhounoted.