中科院-脊椎动物课件

脊椎动物的进化古脊椎动物学：化石所讲述的“脊椎动物进化”的故事教学目的本课程将脊椎动物的进化置于地质历史的框架中予以介绍，重点介绍一些高阶元类群（如脊椎动物、四足动物、鸟类、哺乳动物）的起源、早期进化历史以及最新研究进展。本课程主要让学生认识脊椎动物进化的基本格局，并了解脊椎动物重要类群起源、灭绝与辐射的环境控制因素，为进一步开展古脊椎动物学、古人类学、进化生物学研究工作积累知识。教学安排引言（基本概念、基础知识）—（4）脊椎动物的起源与无颌脊椎动物的进化（2）

有颌类的起源与早期进化（3）从水到陆（3）早期陆生脊椎动物群（4）

恐龙起源、进化与灭绝（5）教学安排（续）鸟类起源与进化（3）哺乳动物的起源与早期进化（3）

新生代哺乳动物的辐射与环境背景（4）

哺乳动物重要类群的起源与进化（5）教学实习（京郊野外考察，4）第一章（讲）引言进化的实证——化石地质时代地质时代中脊椎动物的发展顺序分类学知识分支（支序）系统学基本概念：支序图“化石”概念的嬗变OLDERDEFINITIONS -Anythingdugfromtheground（拉丁语原义：“掘出物”（dugup），指任何埋藏的东西。不但包括石化的动物、植物遗骸，还包括岩石、矿石和人工制品，如古钱币。） -Religiousconnotationsre.Fossils: Noachianfloodsleftmarineorganismsinmountains；Satanputobjectsingroundtoconfuseus；Bonesgrowwhenplantedintheground；Organismsoftheunderworld.实体化石代表生物遗体或遗体的一部分硅化木遗迹化石通常指古代生物生活活动时在底质（生物栖息的场所，如沉积物和贝壳）表面或内部留下的活动痕迹。动物在软质底质上行走时所留下的足迹(track)，高等动物留下的脚印，低等动物移动时在底质中留下的移迹(trail)，生物在硬质底质中钻蚀的栖孔(boring)，在软质底质表而或内部挖掘的潜穴(burrow)等，是常见的遗迹化石。遗迹化石还包括粪团(coprolite)、粪粒(fecalpellet)、蛋、卵、珍珠(双壳纲分泌的)、胃石(gastrolith)等生物代谢、排泄、生殖的产物，甚至还包括古人类所使用的石器(stoneimplement)和骨器以及由外物胶结而成的低等动物栖管(tube)等生物制品(artifact)。

Explosionoflifeformsbetween800-600m.y.ago,baseofCambrian

Invertebrate(imagesoflifeimmediatelybeforetheCambrianPeriod)化学化石古代生物的遗体有些因腐烂分解而消失，但组成生物体的一些残留有机物分子，可在化石中或掺入沉积物中而获得保存。这些保存在岩石中的有机物分，构成了第三类化石即化学化石(chemicalfossil)或分子化石(molecularfossil)。这些未经变化或经历变化的残留有机物分子可保存在各个时代的沉积物和化石遗体内。人们已从这类化石中分离出许多有机物，如蛋白质及其分解的氨基碳、脂肪酸、糖类、烃及色素等。——分子古生物学化石保存的条件从生物本身条件来说，最好具有硬体(hardpart)，因为软体易腐烂、消失。当然软体在特定条件下也可形成化石，但为数不多。无脊椎动物的硬体多是壳体，其成分多为文石(如硬珊瑚)或方解石(如棘皮动物)和有机物基质。一些低等生物如放射虫等为硅质蛋白石。少数硬体是复杂的有机物几丁质(chitin)和硬蛋白质，前者是合氮的多糖类(如昆虫)，后容是不溶的纤维蛋白质(如笔石)。脊椎动物的硬体主要是硬骨(bone)和牙齿。硬骨由磷酸钙组成，并含骨胶原(collagen，一种硬蛋白质)；牙齿也由钙盐组成，致密，表西有珐琅质，几乎为纯的磷酸钙和碳酸盐。植物的硬体为多糖类的纤维素和复杂的芳香化合物木质素(lignin)。从外界环境来说，化石保存的条件最好是有掩盖物质将遗体迅速掩埋起来，免遭生物、机械和化学的破坏。常见的生物破坏是腐食动物、细菌、孔栖生物的吞食和破坏。机械破坏，主要是风沙、波浪、汗流等的冲击和磨蚀。其破坏能力主要取决于硬体结构的坚实程度。化学破坏主要是水体溶解各种硬体成分。其溶解的能力，主要取决于硬体的矿物组成，也取决于水的性质。TAPHONOMY（埋藏学）

(Preservationafterdeath)EventsafterdeathPre-burialwithtotalloss:Bacterialdecompositionunderoxidativeconditions(C->CO2;N->NOx;H->H2O).Scavengers(animals,insects,bacteria,fungusetc.)Mechanicaldecomposition(waves,currents,wind,trampling,chewing).Pre-burialbutwithpreservation:Mummification(desiccation,freezing).Encasement(viz.inamber).化石保存的方式未变保存变化保存铸摸保存未变保存密封Encasement(viz.inamber)冰冻Freezing：北极地区更新统的猛犸象干燥Desiccation(木乃伊化Mummification)模铸保存

印痕(impression)外模(externalmold]、内模(internalmold)和复合模(compositemold)铸型(cast)和复型(replica)

宙代纪显生宙新生代第四纪新近纪古近纪中生代白垩纪侏罗纪三叠纪古生代二叠纪石炭纪泥盆纪志留纪奥陶纪寒武纪

前寒武纪

全新世更新世上新世中新世渐新世始新世古新世CenozoicTimescaleGeologicTimeMetaphorTwowaystodate

geologicevents1)relativedating(fossils,structure)2)absolutedating(isotopic,treerings,etc.)1)relativedating(fossils,structure)2)absolutedating(isotopic,treerings,etc.)EarlyGeologists

NicolausStenoLawsofStratigraphyEachstratumisdepositedfromfluiduponasolidsubjacentsurface--hard(solid)fossilsmaybeincorporatedintosoft(loose)sedimentatthisstageEachstratumislaterallycontinuousandapproximatelyhorizontal.Superposition(stacking)ofstratatakesplaceaccordingtoage.Anydeviationisduetolateralteration--earthquake,volcano,etc.FirsttoproposethatfossilswererecordsofpreviouslivingorganismsImportanceofrunningwaterinshapingtheEarth’ssurfaceSteno'sLawsNicolausSteno(1669)PrincipleofSuperposition PrincipleofOriginalHorizontalityPrincipleofLateralContinuityLawsapplytobothsedimentaryandvolcanicrocks.PrincipleofSuperpositionInasequenceofundisturbedlayeredrocks,theoldestrocksareonthebottom.JimSteinberg/PhotoResearchersOldestrocksYoungestrocksPrincipleofSuperpositionPrincipleofOriginalHorizontalityLayeredstrataaredepositedhorizontalornearlyhorizontalornearlyparalleltotheEarth’ssurface.PrinciplesoforiginalhorizontalityandsuperpositionPrincipleofLateralContinuityLayeredrocksaredepositedincontinuouscontact.PrincipleofLateralContinuityMap

viewPrincipleofLateralContinuityMapviewPrincipleofLateralContinuityMapviewUsingFossilstoCorrelateRocksUnconformityAburiedsurfaceoferosionSedimentationofBedsA-DBeneaththeSeaUpliftandExposureofDtoErosionContinuedErosionRemovesDandExposesCtoErosionUnconformity:aburiedsurfaceoferosionSubsidenceandSedimentationofEoverCFormationofaDisconformityFig.9.6Angularunconformity,GrandCanyonSedimentationofBedsA-DBeneaththeSeaDeformationandErosionDuringMountainBuilding

ErosionalSurfaceCutsAcrossDeformedRocksSubsidenceandSubsequentDepositionBuriesErosionalSurfaceAngularUnconformityFormationofan

AngularUnconformity（三）地质时代中脊椎动物的发展顺序

Taxonomy=scienceofclassifying;thestudyoftherelationshipsbetweengroupsoforganisms.Taxonomyistheartofclassifyingthingsintogroups—aquintessentialhumanbehavior—establishedasamainstreamscientificfieldbyCarolusLinnaeus(1707-1778).1758“thesystemofnature,animalkingdom”10thedition.Eachspeciesgivenabinomen.

分类学（Taxonomy）知识ClassificationofspeciesintohighertaxaKingdomPhylumClassOrderFamilyGenusSpecies分类单元（taxon；taxa）Canbedividedintosuper,sub,infraCanbedividedintosub

tribe

KingdomPhylumClassOrderFamily“-idea”animals,“-aceae”plantsGenus;noun-italicizedorunderlined,capitalized-GreekorLatinSpecies;withgenus,italicizedorunderlined,noun+adjective,sameadjectivemayapplytodifferentspecies-lowercaseMustbeuniqueTaxonomyHomosapiensSimilarity(相似性）Pre-DarwinianClassificationClusteringbysimilarityandbycommondescentPost-DarwinianClassificationTruesimilarityvs.falsesimilarity无颌纲（Agnatha）盾皮鱼纲（Placodermi）棘鱼纲（Acanthodii）软骨鱼纲（Chondrichthyes）硬骨鱼纲（Osteichthyes）两栖纲（Amphibia）爬行纲（Reptilia）鸟纲（Aves）哺乳纲（Mammalia）鱼形总纲（Pisces）四足类总纲（Tetrapoda）脊椎动物亚门（Vertebrata）脊椎动物的分类PhylogeneticsEvolutionarytheorystatesthatgroupsofsimilarorganismsaredescendedfromacommonancestor.Phylogeneticsystematics(cladistics)isamethodoftaxonomicclassificationbasedontheirevolutionaryhistory.ItwasdevelopedbyWilliHennig,aGermanentomologist,in1950.TypesofTaxonomicGroupsMonophyleticgroup=ataxonthatincludesalldescendantsofcommonancestor(=naturalgroup,holophyleticgroup)Polyphyleticgroup=ataxonthatincludesgroupsfromtwounrelatedlineagesParaphyleticgroup=ataxonthatincludessome,butnotalldescendantsofacommonancestorTypesofTaxonomicGroups1-Monophyletic2-Paraphyletic3-PolyphyleticABCDECladisticMethodsEvolutionaryrelationshipsaredocumentedbycreatingabranchingstructure,termedaphylogenyortree,thatillustratestherelationshipsbetweenthesequences.Cladisticmethodsconstructatree(cladogram)byconsideringthevariouspossiblepathwaysofevolutionandchoosefromamongthesethebestpossibletree.

Aphylogramisatreewithbranchesthatareproportionaltoevolutionarydistances.分支（支序）系统学基本概念Codingofcharactersisagoodapproach-requireabettermeansofanalysisofcharacterdistributionsGoalistorecognizemonophyletic(holophyletic)taxa-alldescendantsofacommonancestorTracedistributionsofcharactersamongtaxatoidentifylinesofcommonancestryPhylogeneticSystematics-CladisticsApomorphyadvancedorderivedtrait-newcharacterorcharacterstatethosethatservetodistinguishataxonfromitsancestorsPlesiomorphyprimitivetrait-inheritedfromancestorCladisticsAutapomorphy

derivedcharacterheldbyonlyonegroupoforganismsOfnouseindeterminingrelationshipswithothergroupsUsefulforcharacterizingthatgroupCladisticsSynapomorphy

Derivedtraitthatissharedby2ormoregroupsoforganismsUsefulinestablishingrelationshipsbetweengroupsoneormoresynampomorphiessharedinsistergroups,closelyrelatedtaxaPhylogeneticSystematics-CladisticsEstablishingrelationshipsamonggroupsoforganismsonthebasisofshared,derivedcharacters-synapomorphiesnotallcharactersareimportantonlytheuniqueevolutionarynoveltiesCladisticsAparticularcharactermayhaveadifferentvalue,dependingonthelevelofanalysisE.g.bivalveshellsofBivalvesAutapomorphicforbivalvesasawhole(nousefordeterminingrelationtoothermolluscgroups)SynapomorphicforallorderswithinBivalvia(distinguishesthemfromotherMolluscgroups)PleisomorphicwithrespecttofinersubdivisionswithinBivalvia-can’tbeusedtodistinguisharazorclamfromamusselcladogramNode,commonancestortaxaSynapomorphies,derivedcharactersofmammalspleisomorphies,primitivecharactersofsharks,frogs,cows,monkeys,humansCladisticsCharactersmayberepresentedonlyinabinarystatePRESENTorABSENTOrinmultiplestates(absent,slightlydeveloped,well-developed,eg.Headspinesontrilobites)orincreasingdecreasingnumbersofafeature(ungulatetoes)Whichisthederivedcharacterandwhichistheprimitivecharacter? CharacterPolarityCladisticsCharacterPolarity-howtoassessageofappearanceinthefossilrecordProblem:fossilrecordisincompleteOutgroupcomparison–examinethedistributionofthischaracteramongcloserelativesoutsidethestudygroupcladogramAbsenceofhairormammaryglandsintheoutgroupsfrog,shark,lampreyShellsymmetryinbivalves3states–2planesofsymmetryBivalvesymmetrybutbilateralasymmetryBivalveandbilateralsymmetryneitherbivalvenorbilateralsymmetryoysters-somewithnosymmetry,comparisonwithotherbivalvesymmetry,theasymmetryisnotcommon(notinoutgroups)andisprobablyderivedscallops-bilateralsymmetryofnon-swimmingforms,alsoderived.

BilateralsymmetryBivalvesymmetrycommoncommonalitywidespreadfeatureswithinagroupareprobablyprimitive,rareonesprobablyderived.EmbryologicaldevelopmentusuallyderivedcharacterstatesdeveloplaterinearlyontogenyoftendifficulttoapplytoextincttaxaIfpossible,shouldaffirmthatstructuresseeninvariousgroupsarehomologous-thiswillbetestedintheoutcomeoftheanalysis

charactersofunknownpolaritywillbedeterminedbyanalysisCladogram5trilobites(A-E)usedthemtoshownumericaltaxonomyresultedinaphenogram(6.2)Forcladisticsemphasisoncladogenesisnotanagenesislookingforprimitivevsderivedcharactershypothesis-lowernumberingofcharactermayrepresentsmoreprimitive,e.g.HdSp0moreprimativethanHdSp3

CkEmisuniqueforthattaxon=autoapomorphous,doesnotcontributetothecladisticanalysis(6.4A)allremainingfeatureshavederivedcharactersthatgrouptwoormoreofthe5trilobitesproduce5featuretrees(6.4B-F)Cladogramcladogram6featuresinonetree(6.4C)HdSp3OcSg2Th4Sp2areautapomorphous4featuretreesarecompatible(6.4C-F)one(6.4B)isgroupsTriAwithTriE,thisisindistinctconflictwiththeothers,thereforeassumedtobeparallelevolutioncladogram6.4C,6featuresshowthatDandEformamonophyleticgroup6.4D,showsthatC,D,andEformanother,largermonophyleticgroup6.4F,supportsthesameconclusioncombineintosinglecladogram(6.5)nodes(1-4)arespeciationeventsTriBhasnocharacteronitsclade(branch),possiblethatBandnode2arethesame,butpossilbethatcharactersuniquetoBhavebeenmissedCladisticsPrincipleofParsimonyThesimplestsolutiontothedistributionofcharacters-i.e.thefewestnumberofbranchingevents-isprobablythecorrectsolutionthisrepresentsthesmallestnumberofhomoplasiesCladisticsWhataboutancestors?Nodesrepresentmostrecentcommonancestors-thepointoforiginationofasynapomorphyusuallytreatedashypotheticalentitiesifonememberofacladeisnotdistinguishedfromthenodebyany(orveryfew)synapomorphies,itmaybetheancestoroftheothertaxainthecladeCladisticsAcladogramisatestablehypothesisofrelationshipswithadditionofnewcharactersorcharacterstateswithadditionofdifferenttaxawithselectionofadifferentoutgroup,polarity,characterweighting,ordering,etc.CladogramtophylogramExpressanagenesislengthandangleofbranchesofcladogramchangedtoreflectamountofchangeinferredforeachbranchresultingphylogram(6.6)showsthatABCgroup(paraphyletic)andDE(monophyletic)aredistinct(majorgapsbetweennodes3and4Phenogram(6.2)andphylogram(6.6)demonstratesimilaritiesinABCandDE,butbranchingsequencesaredifferentcladogram(6.5)andphylogramhaveidenticalbranchingpatterns,butsimilaritiesofABCarenotevidentin6.5PhylogeneticClassificationtaxonomybasedonstrictinterpretationofcladogramdefinem