中科院-脊椎動物課件

脊椎動物的進化古脊椎動物學(xué)：化石所講述的“脊椎動物進化”的故事教學(xué)目的本課程將脊椎動物的進化置于地質(zhì)歷史的框架中予以介紹，重點介紹一些高階元類群（如脊椎動物、四足動物、鳥類、哺乳動物）的起源、早期進化歷史以及最新研究進展。本課程主要讓學(xué)生認(rèn)識脊椎動物進化的基本格局，并了解脊椎動物重要類群起源、滅絕與輻射的環(huán)境控制因素，為進一步開展古脊椎動物學(xué)、古人類學(xué)、進化生物學(xué)研究工作積累知識。教學(xué)安排引言（基本概念、基礎(chǔ)知識）—（4）脊椎動物的起源與無頜脊椎動物的進化（2）

有頜類的起源與早期進化（3）從水到陸（3）早期陸生脊椎動物群（4）

恐龍起源、進化與滅絕（5）教學(xué)安排（續(xù)）鳥類起源與進化（3）哺乳動物的起源與早期進化（3）

新生代哺乳動物的輻射與環(huán)境背景（4）

哺乳動物重要類群的起源與進化（5）教學(xué)實習(xí)（京郊野外考察，4）第一章（講）引言進化的實證——化石地質(zhì)時代地質(zhì)時代中脊椎動物的發(fā)展順序分類學(xué)知識分支（支序）系統(tǒng)學(xué)基本概念：支序圖“化石”概念的嬗變OLDERDEFINITIONS -Anythingdugfromtheground（拉丁語原義：“掘出物”（dugup），指任何埋藏的東西。不但包括石化的動物、植物遺骸，還包括巖石、礦石和人工制品，如古錢幣。） -Religiousconnotationsre.Fossils: Noachianfloodsleftmarineorganismsinmountains；Satanputobjectsingroundtoconfuseus；Bonesgrowwhenplantedintheground；Organismsoftheunderworld.實體化石代表生物遺體或遺體的一部分硅化木遺跡化石通常指古代生物生活活動時在底質(zhì)（生物棲息的場所，如沉積物和貝殼）表面或內(nèi)部留下的活動痕跡。動物在軟質(zhì)底質(zhì)上行走時所留下的足跡(track)，高等動物留下的腳印，低等動物移動時在底質(zhì)中留下的移跡(trail)，生物在硬質(zhì)底質(zhì)中鉆蝕的棲孔(boring)，在軟質(zhì)底質(zhì)表而或內(nèi)部挖掘的潛穴(burrow)等，是常見的遺跡化石。遺跡化石還包括糞團(coprolite)、糞粒(fecalpellet)、蛋、卵、珍珠(雙殼綱分泌的)、胃石(gastrolith)等生物代謝、排泄、生殖的產(chǎn)物，甚至還包括古人類所使用的石器(stoneimplement)和骨器以及由外物膠結(jié)而成的低等動物棲管(tube)等生物制品(artifact)。

Explosionoflifeformsbetween800-600m.y.ago,baseofCambrian

Invertebrate(imagesoflifeimmediatelybeforetheCambrianPeriod)化學(xué)化石古代生物的遺體有些因腐爛分解而消失，但組成生物體的一些殘留有機物分子，可在化石中或摻入沉積物中而獲得保存。這些保存在巖石中的有機物分，構(gòu)成了第三類化石即化學(xué)化石(chemicalfossil)或分子化石(molecularfossil)。這些未經(jīng)變化或經(jīng)歷變化的殘留有機物分子可保存在各個時代的沉積物和化石遺體內(nèi)。人們已從這類化石中分離出許多有機物，如蛋白質(zhì)及其分解的氨基碳、脂肪酸、糖類、烴及色素等?！肿庸派飳W(xué)化石保存的條件從生物本身條件來說，最好具有硬體(hardpart)，因為軟體易腐爛、消失。當(dāng)然軟體在特定條件下也可形成化石，但為數(shù)不多。無脊椎動物的硬體多是殼體，其成分多為文石(如硬珊瑚)或方解石(如棘皮動物)和有機物基質(zhì)。一些低等生物如放射蟲等為硅質(zhì)蛋白石。少數(shù)硬體是復(fù)雜的有機物幾丁質(zhì)(chitin)和硬蛋白質(zhì)，前者是合氮的多糖類(如昆蟲)，后容是不溶的纖維蛋白質(zhì)(如筆石)。脊椎動物的硬體主要是硬骨(bone)和牙齒。硬骨由磷酸鈣組成，并含骨膠原(collagen，一種硬蛋白質(zhì))；牙齒也由鈣鹽組成，致密，表西有琺瑯質(zhì)，幾乎為純的磷酸鈣和碳酸鹽。植物的硬體為多糖類的纖維素和復(fù)雜的芳香化合物木質(zhì)素(lignin)。從外界環(huán)境來說，化石保存的條件最好是有掩蓋物質(zhì)將遺體迅速掩埋起來，免遭生物、機械和化學(xué)的破壞。常見的生物破壞是腐食動物、細(xì)菌、孔棲生物的吞食和破壞。機械破壞，主要是風(fēng)沙、波浪、汗流等的沖擊和磨蝕。其破壞能力主要取決于硬體結(jié)構(gòu)的堅實程度。化學(xué)破壞主要是水體溶解各種硬體成分。其溶解的能力，主要取決于硬體的礦物組成，也取決于水的性質(zhì)。TAPHONOMY（埋藏學(xué)）

(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).化石保存的方式未變保存變化保存鑄摸保存未變保存密封Encasement(viz.inamber)冰凍Freezing：北極地區(qū)更新統(tǒng)的猛犸象干燥Desiccation(木乃伊化Mummification)模鑄保存

印痕(impression)外模(externalmold]、內(nèi)模(internalmold)和復(fù)合模(compositemold)鑄型(cast)和復(fù)型(replica)

宙代紀(jì)顯生宙新生代第四紀(jì)新近紀(jì)古近紀(jì)中生代白堊紀(jì)侏羅紀(jì)三疊紀(jì)古生代二疊紀(jì)石炭紀(jì)泥盆紀(jì)志留紀(jì)奧陶紀(jì)寒武紀(jì)

前寒武紀(jì)

全新世更新世上新世中新世漸新世始新世古新世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）地質(zhì)時代中脊椎動物的發(fā)展順序

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

分類學(xué)（Taxonomy）知識ClassificationofspeciesintohighertaxaKingdomPhylumClassOrderFamilyGenusSpecies分類單元（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無頜綱（Agnatha）盾皮魚綱（Placodermi）棘魚綱（Acanthodii）軟骨魚綱（Chondrichthyes）硬骨魚綱（Osteichthyes）兩棲綱（Amphibia）爬行綱（Reptilia）鳥綱（Aves）哺乳綱（Mammalia）魚形總綱（Pisces）四足類總綱（Tetrapoda）脊椎動物亞門（Vertebrata）脊椎動物的分類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）系統(tǒng)學(xué)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