-
Research progress in Ediacaran biostratigraphy of South China
SilicifiedmicrofossilsfromtheDoushantuoFormationattheLujiayuanzisectionDoushantuo-Pertatatakaacritarchs(DPAs)areabundantandwellpreservedintheEdiacaranDoushantuoFormationinSouthChina.NotonlydotheyprovideinsightsintothemarineecosystemimmediatelyafteraNeoproterozoicglobalglaciation,theyalsoaffordusanidealtoolforEdiacaranstratigraphicsubdivisionandcorrelation.However,previousreportsofDPAsinSouthChinaaremostlyfromtheYangtzeGorgesareainintra-shelfbasinandfromWeng’aninshelfmarginenvironments,whiledatafromlocalitiesinslopeandbasinalfaciesarelacking. Inrecentyears,OUYANGQingandcolleaguesfromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofScienceshavecarriedoutstratigraphicandmicrofossilinvestigationsforanupperslopesectionoftheDoushantuoFormationatLujiayuanziinnorthwesternHunanProvince,SouthChina.FiveDPAgeneraandeightspecieshavebeendiscoveredfromtheDoushantuoFormationchertnodules,withtheuppermosttwoDPAhorizonsoccurringaboveaδ13CnegativeexcursionthatiscorrelatedwiththeEN3/Shuramexcursionbasedonintegratedlitho-andchemostratigraphiccorrelation.ThenewfindingsrevealabroadertemporalandspatialdistributionofDPAsinSouthChina,andfurthersupporttheirbiostratigraphicpotentialintheearlymiddleEdiacaransubdivisionandcorrelation. Lithostratigraphiccolumn,fossiloccurrences,andchemostratigraphyoftheLujiayuanzisectionThisworkwassupportedbytheStrategicPriorityResearchProgram(B)ofChineseAcademyofSciences(grantnumberXDB18000000),theNationalNaturalScienceFoundationofChina(grantnumber41672027),NationalBasicResearchProgramofChina(grantnumber2013CB835005),andtheUSNationalScienceFoundation(EAR1528553). Articleinformation:Ouyang,Q.,Guan,C.,Zhou,C.*,Xiao,S.,2017,AcanthomorphicacritarchsoftheDoushantuoFormationfromanupperslopesectioninnorthwesternHunanProvince,SouthChina,withimplicationsforearly–middleEdiacaranbiostratigraphy.PrecambrianResearch,298:512–529.
2017-08-09
-
Middle–Upper Ordovician chitinozoan assemblage from Yangtze Platform
LithologyandchitinozoanstratigraphicrangesoftheMiddle–UpperOrdovicianMiaopoFormationatJieling,northernYichang,westernHubei. Asanextinctgroupoforganic-walled,plankticmicrofossils,chitinozoanischaracterizedbyitswidedistributionandshorttemporalrangeofitsspecies,whichenablesittobecomeanimportanttoolinthestratigraphiccorrelation.ThemostsignificantchitinozoanacmeappearedinthelateMiddletoearlyLateOrdovicianinBalticaandNorthGondwana.ArelativelyhighdiversityvaluealsoappearedduringthistimeintervalinLaurentia.However,chitinozoanbiodiversityintheYangtzePlatform,aswellasinChina,wasoriginallythoughttobefairlylowforthistimeintervalincomparisonwiththoseofothermajorpalaeoplatesorterranes.Andthechitinozoanbiostratigraphicsequenceforthistimeintervalrequiresfurtherworkforregionalandglobalcorrelations. Duringthelasttwoyears,Dr.LIANGYanfromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencesandhercolleaguesdescribedandanalyzedadiverseandabundantchitinozoanassemblagefromtheMiddle–UpperOrdovicianMiaopoFormationatJieling,YichangareaofSouthChina.Forty-threespeciesof16generawereidentified,whichsubstantiallyincreasesthechitinozoandiversityofthisparticulartimeintervaloftheSouthChinapalaeoplate. BiostratigraphicsubdivisionandcorrelationoftheMiddle–UpperOrdovicianinSouthChinaandBaltica.SeveralkeychitinozoanspeciesfromNorthGondwanaandBalticaarereportedforthefirsttimeinChina.ThechitinozoansofthisformationhavemixedNorthGondwanaandBalticapalaeogeographicaffinities.TherecognitionofLaufeldochitinastentorandArmoricochitinagranuliferaguaranteesabetterbiostratigraphiccorrelationbetweenSouthChinaandBaltica.Mostoftheformation,exceptforitstopmostpart,isassignedtotheL.stentorBiozone,whichcanbefurthersubdividedintotwosubzones:theCyathochitinamegacalixsp.nov.Subzone(lower)andtheA.granuliferaSubzone(upper).Additionally,threenewspeciesareformallydescribed,includingC.megacalixsp.nov.,Cyathochitinararicostatasp.nov.andEisenackitinatenuissp.nov. ThisresearchwasfundedbytheNationalNaturalScienceFoundationofChina,StateKeyLaboratoryofPalaeobiologyandStratigraphy,NanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciences.ThispaperisacontributiontotheIGCP653(TheOnsetoftheGreatOrdovicianBiodiversificationEvent). Articleinformation:YanLiang,FlorentinParis,PengTang.2017.Middle–LateOrdovicianchitinozoansfromtheYichangarea,SouthChina.ReviewofPalaeobotanyandPalynology244,26-42.Doi:10.1016/j.revpalbo.2017.04.004.
2017-08-09
-
The ecological effect through the end Ordovician mass extinction
Diagramshowingthegeneric(diversity)andspecimen(abundance)percentagesofvariousmajorgroupsoflateHirnantianandearlyRhuddanianbrachiopods(theCathaysiorthisfauna),andlateKatianbrachiopodsintheJiangnanRegion,SoutheastChina. Classificationofextinctioneventsandtheirseverityisgenerallybasedontaxonomiccounts.Theecologicalimpactsofsucheventshavebeencategorizedandprioritizedbutrarelytestedwithempiricaldata.Inarecentstudy,theecologicalseverityoftheendOrdovicianeventwasconsideredevenlesssignificantthanthatoftheSerpukhovian,andisrankedonlysixthwithintheelevenlargestPhanerozoiccrisessincethebeginningoftheOrdovicianPeriod. SouthChinaoffersakeyopportunitytoexaminetheecologicalchangesthroughtheendOrdovicianeventindetail.Recently,totesttheecologicalchangethroughtheendOrdovicianmassextinction,astudycarriedonbyProf.HUANGBing,CASAcademicianRONGJiayuandProf.ZHANRenbinfromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencestogetherwithDavidA.T.HarperfromDepartmentofEarthSciences,DurhamUniversity,UK. ThestudybasedonthedatafromtheCathaysiorthisfaunawhichdominatedbybrachiopodsfromtheuppermostOrdoviciantolowermostSilurianofSEChina,succeedingthecool-waterHirnantiaFauna.Thefaunaisabundantandhasarelativelyhighdiversity;thesedatawerereportedwiththedetailedsystematicdescriptionsofthefauna.Thespatialandtemporalrangesofmorethan6,500identifiedspecimens,from10collectionsderivedfrom6localitieswereinvestigatedbynetworkandclusteranalyses,nonmetricmultidimensionalscalingandaspeciesabundancemodel.TheecologicalcircumstancesofthesurvivalbrachiopodfaunaaftertheendOrdovicianmassextinctionwereevaluated. Other,olderbrachiopodfaunas,AltaethyrellafaunaandFoliomenafauna,characterizingthelateKatianwithinthesameareaarecomparedintermsofdiversity,populationstructure,benthicassemblagezonesandrelativeabundancetogetherwiththeirmajorcomponentstohelpfurtherelucidatetheecological‘turnover’throughtheendOrdovicianextinctioneventinSouthChina.Depthzonationsandstructureofbrachiopodassemblagesalonganonshore-offshoregradientinthelateKatianweresimilartothoseinthelatestOrdovician–earliestSilurian(post–extinctionfauna).Thewidthsofecologicalrangearesimilarbetweenbeforeandimmediatelyafterthecrisisthatmaysuggestthelimitedecologicaleffectoftheevent. Withinthisecologicalframework,deeper-waterfaunasarepartlyreplacedbynewtaxa;siliciclasticsubstratescontinuedtobedominatedbythemore‘Ordovician’orthidesandstrophomenides,shallow-watercarbonateenvironmentshostedatrypides,athyrididesandpentamerides,withthemoretypicalOrdovicianbrachiopodfaunacontinuingtodominateuntilthelateRhuddanian.TheendOrdovicianextinctionstestedtheresilienceofthebrachiopodfaunawithoutdamagetoitsoverallecologicalstructure;thatcommencedlaterattheendoftheRhuddanian. Reference:HuangBing,HarperDAT,RongJiayu,ZhanRenbin.2017.BrachiopodfaunasaftertheendOrdovicianmassextinctionfromSouthChina:Testingecologicalchangethroughamajortaxonomiccrisis.JournalofAsianEarthSciences,138:502–514.
2017-08-09
-
Morphological study of clam shrimps Diestheria from Jehol Biota
SEMimagesofDiestherialonginquaChen,inZhangetal.,1976,emend.（Fig.1alightmicroscopyimage)Clamshrimps(conchostracans)arelargefreshwaterbranchiopodcrustaceanswithachitinouscarapace(afewmillimetertotwocentimetersinsize)thathavealonggeologicalhistoryextendingbacktotheDevonian.Extantclamshrimpsnormallyinhabitquiet,alkalinefreshwaterpools,andoftenoccurintemporarywaterbodieslikericefieldandevenrainpools.Theyareusefulforbiostratigraphicsubdivisionandcorrelationofnon-marinesuccessions.ThefossilspinicaudatangenusDiestheriaChenisanimportantcomponentofthediverseEosestheriafaunaoftheEarlyCretaceousJeholBiotainnorthernChina.ThestudiedtypespecimensofDiestherialonginquaChen,inZhangetal.,1976wereoriginallycollectedfromtheLowerCretaceousYixianFormationatDakangpuofYixianCounty,westernLiaoningProvince,northeasternChina.TheyaredepositedinthecollectionoftheNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciences(NIGPCAS).Theholotype(NIGPCAS15462)isanexternalmouldofaleftvalveandtheparatype(NIGPCAS15463)isarightvalve.Mostofthepreviousstudiesonthepalaeontologyoffossilclamshrimpshaveusedalightmicroscope.Thismeansthatsomemorphologicalcharactersofpotentialtaxonomicvalueweredifficulttoseeclearly.Recently,M.S.LIYuling,M.S.TENGXiao,Prof.LIGangfromNIGPCASandProf.MATSUOKAAtsushifromNiigataUniv.re-examinedtheparatypespecimen(NIGPCAS15463)ofDiestherialonginquausingaLEO1530VPscanningelectronmicroscope(SEM).Andthemorphologicalre-examinationunderanSEMrevealedmorphologicalfeaturesonthecarapacethathavenotbeenrecognizedpreviously:1)growthlineswithfineridges;2)radialliraeintercalatedwithsmallirregularreticulationonthegrowthbandsinthepostero-middlepartofthecarapace.TheherediscovereddelicatereticulationbetweenradialliraeisdifferentfromtheevenlydistributedpunctafoundinNeodiestheria.ThisstudyindicatesthatitisnecessarytocarryoutafurthermorphologicalstudyonotherspeciesofDiestheriainthefuture.TheresearchwasrecentlypublishedinthejournalSci.Rep.NiigataUniv.(Geology).ThisresearchwasfundedbytheNationalNaturalScienceFoundationofChina.Relatedinformationofthispaper:YulingLI,XiaoTENG,AtsushiMATSUOKA,GangLI,2017.SEMmorphologicalstudyofclamshrimpDiestheria(spinicaudatan)oftheJeholBiotaofChina.Sci.Rep.NiigataUniv.(Geology),No.31,6974.
2017-08-09
-
New progress on the study of clam shrimps from Yanji Basin
ClamshrimpOrdosestheriamulticostata Clamshrimps(conchostracans)arefreshwaterbranchiopodcrustaceanswithahingedchitinousorcomplexchitin-mineralcarapace.TheyareknowninthefossilrecordfromtheDevoniantorecent.SincethePennsylvanian,clamshrimpshavebeenanimportantandwidespreadcomponentinnon-marine,aquaticbiotopes.Theyareusefulforbiostratigraphicsubdivisionandcorrelationofnon-marinesuccessions. TheYanjiestheriafaunaoccurswidelyinthenon-marineLowerCretaceousrocksofEastAsiaandisprincipallycomposedofNeodiestheria,Orthestheria,OrthestheriopsisandYanjiestheria.ThenominatedgenusYanjiestheriaCheninZhangetal.,1976waserectedbasingonspecimenscollectedfromtheupperAlbianDalaziFormationintheYanjiBasin,JilinProvince,north-easternChina,andhasbeenreportedsubsequentlyfromtheLowerCretaceousinthesouth-easternChina,north-westernChina,Koreaandsouth-westernJapan. Recently,M.Sc.TENGXiaoandProf.LIGangfromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencesrecoveredspeciesofOrdosestheriafromtheupperAlbianDalaziFormationinnorth-easternChina,whichwerepreviouslyidentifiedasorthestheriids.Thismeansthatthedistributionofordosestheriidsiswiderthanwethoughtbefore,andthisgenuscanbeanindexgenusforthesubdivisionofthenon-marinesequencesinChina. AccordingtopreviousstudiestheauthorsofthepresentresearchtentativelyproposethatordosestheriidsfirstoriginatedfromnorthernAfricaintheearlyBarremian,duringtheearlyAptiantransgressiontheyescapedfromnorthernAfricaanddispersedtotheOrdosBasinofeasternAsia,thentheyfurtherdispersedeastwardtothewesternpalaeo-PacificcoastalareaandcolonizedintheYanjiBasininlateAlbian. ThisresearchwasfundedbytheNationalNaturalScienceFoundationofChina,andbyChineseAcademyofSciences(XDPB05).Relatedinformationofthispaper:XiaoTeng,GangLi.2017.ClamshrimpgenusOrdosestheriafromtheLowerCretaceousDalaziFormationinJilinProvince,north-easternChina.CretaceousResearch,doi:10.1016/j.cretres.2017.06.011.
2017-07-20
-
Euphyllophytes have abundant fossil records in the Upper Devonian
Transversesectionoffern-likeplantShougangiastemfromtheUpperDevonianofChina AfurtherstudyontheanatomyofShougangiabellafromtheLateDevonian(Famennian)ofSouthChinaiscarriedontheworkgroupofProf.XUHonghefromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencesandProf.WangDemingfromPekingUniversity.ThestudyreleasetheanatomyfeatureofShougangiaandprovideareconstructionbasedonitsknownmorphology,whichwasstudiedbythempreviously. Shougangiastemscontainadissectedstelewithafour-ribbedandanelongatecurvedprimaryxylemsegmentschangingtothreeelongateandslightlycurvedsegments.Primarybrancheshaveadissectedstelewiththreesimilarprimaryxylemsegmentsasinstems.Theprimaryxylemofthestemsandprimarybranchesismesarch,andindividualprimaryxylemsegmentsbearperipheralprotoxylemstrandsandaresurroundedbysecondaryxylem.Shougangiaisanatomicallycomparedwithfern-likeplants,zygopteridfernsandearlyseedplants,verifyingitsuncertainaffinityatclassandorderlevelsassuggestedbymorphology,orrepresentinganeworderwithintheCladoxylopsida.BytheLateDevonian,besidestheabruptdropofatmosphericCO2levels,thepresenceofsecondaryxylemmaycorrelatewellwiththeprimaryradiationofleaves(megaphylls)ofeuphyllophytes(e.g.fern-likeplants,sphenopsids,progymnospermsandseedplants). Reconstructionofmorphology(A)andanatomy(B–D)oftheLateDevonianfern-likeplantShougangiafromChina Reference:WangD-M*,ZhangY-Y,LiuL,XuH-H*,QinM,LiuL.2017.ReinvestigationoftheLateDevonianShougangiabellaandnewinsightsintotheevolutionoffern-likeplants,JournalofSystematicPalaeontology.Doi:10.1080/14772019.2017.1289269
2017-07-20
-
A diminutive euphyllophyte from the Middle Devonian of Xinjiang verified transitional evolution of plants
Adiminutiveeuphyllophyte,Douaphytonlevigata,fromtheMiddleDevonianofXinjiang,thevegetitaveandfertilespeicmens.Thegridintheupperrightcorneroftheleftfigis1mmwide.Devonian(420-360Ma)witnessedaserialofdramaticlandscapechanges.Avarietyoflandplants,includingearlyferns,lycopsidsandzosterophylls,appearedinthelandsofDevonianworld.ThefirstforestalsooccurredintheDevonian.TheWestJunggar,Xinjiang,China,withwell-developedDevoniansequencesandabundantplantfossils,hasbecomearepresentativeandsignificantareaworkingonMiddleDevonianflora. DiminutiveDevonianplants(axiswidthlessthan2mm),foralongtimewereneglectedforthereasonofsmallsizeandthatitishardtofineorganicconnectedspecimensofvegetativeandfertileorgan.Asaresult,fewstudywascarriedondiminutiveDevonianplants,which,however,actasasignificantgrouptostudyplantandfloraevolution,diversityandpalaeophytogergraphy. Recently,adiminutiveeuphyllophyte,Douaphytonlevigatagen.etsp.nov.,isdescribedfromtheupperMiddleDevonian(Givetian)HujiersiteFormationofWestJunggar,Xinjiang,China,byProf.XUHonghefromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencesandhiscollegues.Theplantconsistsofmorethanthreeordersofaxisbranching,eachaxisbeinglessthan2mmwide.Thesecond-orderaxesareshort,laterallyandalternatelyattachedtothemainaxis.Thethird-orderaxesarepairedandanisotomouslydivided,bearingthevegetativeappendagesorthefertileunits.Thefertileunitconsistsofashortrecurvedaxisgivingoffuptofourshortpedicelsalongoneside,eachofwhichbearsonetofourpairsofterminalsporangia.TheplantwasnamedafterthegeologistMr.DOUYawei,whoworkedongeologicsurveytoXinjiangin1970-1980s.Douaphytonhasathree-dimensionalbranchingsystemthathasanintermediateformintheevolutionarycontextofeuphyllophytesandlignophytes.ItisalsoproposedthatcomplexbranchingdevelopedinmultiplegroupsintheMiddleDevonian. Reference:Xu,H.-H.,Wang,Y.,Tang,P.,Wang,Y.,2017.AnewdiminutiveeuphyllophytefromtheMiddleDevonianofWestJunggar,Xinjiang,Chinaanditsevolutionaryimplications.Alcheringa.
2017-07-20
-
Thylacocephala (Arthropoda) from the Lower Triassic of Chaohu, China
Ankitokazocarischaohuensis.scalebarsequal5mmThylacocephala,thoughonlybeenrecognizedfor25years,hasbeenconsideredapeculiargroupworthyofdetailedanatomicalandphylogeneticstudies.Theyarebenthicarthropodsshowinglarge,laterallyflattenedovoid/sub-trapezoidalbivalvedcarapacethatencompassestheentirebodyandhaveatypicalanteriorrostrum-opticnotchcomplex.Generallytheyhavelargecompoundeyes,threelargeraptorialappendages,8gillsandnumerousposteriorappendages.Theirlongtemporaldistribution,fromtheearlyPalaeozoictotheLateCretaceous,isfurnishedbypatchyrecordsthatclearlyreflecttheavailabilityofFossil-Lagersttten.Thetaxonomyandecologyofthisgrouphasbeencontroversialduetothelowdiversityandlackofcompletespecimens. IntheChaohuAreaofAnhuiProvince,acompletestrataoftheEarlyTriassiccanbeobserved.TheChaohuFauna,representedbythediversifiedmarinereptilesandfishesfromtheupperpartofNanlinghuFormation(Spathian,Olenekian),hasbeenregardedasamarkerofthefullrecoveryofmarineecosystemafterPTME.Recently,Dr.JIChengfromNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencesandhercolleguesdiscoverednewmaterialofthylacocephalanfromtheChaohuFaunaanditisalsothefirstreportofthisgroupintheTriassicofSouthChina.Morethanonespeciescanberecognizedbutmajoritybelongstoanewspecies,Ankitokazocarischaohuensis,suggestingaclosegeographiccorrelationwithMadagascarandJapanduringtheSpathianofEarlyTriassic. FromthebedyieldingA.chaohuensis,wealsofoundsomecoprolitefossils,someofwhichcontainconodontsinside.Thesizeandstructureofthesecoprolitescanruleoutthemarinereptilesandfishfromthesamefaunaasproducers.Dr.JIcomparedtherelativesizeofgutandcarapaceofSilurianthylacocephalanThylacaresbrandonensisandtheircoprolitesandfoundthatthesethylacocephalansfromthesamebedcouldpossiblyhaveproducedthecoprolitesaftereatingconodontanimal.Thisisthefirstreportofthepredationbetweenthylacocephalanandconodontanimal.Ontheotherhand,thylacocephalanshavelargecompoundeyesandlargeraptorialappendages,suggestingtheyarecapableofdetectingandgraspingsmallpreylikeshrimpormaybeevenconodontanimalofsimilarsize.Dr.JIalsohaveafewspecimensthatpreserveconodontsinsidethepartialcarapacewherethelatterwasbroken.Theymightberelatedwithgutremainsbutstillneedfurtherevidence. reconstructionofAnkitokazocarischaohuensis(ByYANGDinghuafromNIGPAS)Thisresearchhasbeenrecentlypublishedon-lineinPalontologischeZeitschrift,foundedbyNationalScienceFoundationofChina,CASKeyLaboratoryofEconomicStratigraphyandPalaeogeographyandStateKeyLaboratoryofPalaeobiologyandStratigraphy(NIGPAS). Reference:ChengJi,AndreaTintori,DayongJiangandRyosukeMotani,2017.NewspeciesofThylacocephala(Arthropoda)fromtheSpathian(LowerTriassic)ofChaohu,AnhuiProvinceofChina.PalontologischeZeitschrift,DOI:10.1007/s12542-017-0347-7.
2017-07-20
-
Charophytes uncovering the Cretaceous–Paleogene boundary in the Pingyi Basin, China
Fig.1SomecharophytesfromthePingyiBasin.A-C.Feistiellaanluensis;D-I.Peckicharavarians.varss="图1.山东平邑盆地部分轮藻化石属种";if(ss=="")document.getElementById("d0").style.display="none"; TheCretaceous-Paleogeneboundary(K/Pgboundary)marksthebeginningoftheCenozoic,andisoneofthemostimportantgeologicalboundaries.Theend-Cretaceousextinctionisoneoffivemassextinctionevents,leadingtotheextinctionofammonitesandbelemnitesinthesea.Alsoitistheendofdinosaur’sage.TheK/PgboundaryisrecognizedastheboundaryclayandtheGSSPforthebaseofDanianstageisatthebaseoftheclay.However,itisdifficulttofindtheboundaryclayinnon-marinestrata.Charophytesareusuallyveryabundantinthenon-marinestrataneartheK/Pgboundary,andthesignificantchangesofcharophytefloracanhelptorecognizetheK/Pgboundary. RecentinvestigationconductedbytheDr.LIShafrom“Modernterrestrialecosystemsoriginandearlyevolutionresearchteam”attheNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciences,cooperatedwithCarlesMartín-ClosasfromtheUniversityofBarcelona,studiedthechangeofcharophyteflorasfromtheCretaceous–PaleogenetransitioninthePingyiBasin,ChinaandcorrelateditwithEuropeancharophyteflorasunderthesameage.TheCretaceous–PaleogeneboundarywasraisedinthePingyiBasinandtheresultswerepublishedontheJournalofCretaceousResearch. Traditionally,theidentificationofcharophytesinChinaisusuallybasedonindividualorafewgyrogonitesbutnotthewholepopulation.Suchstudieslackstatisticalmeasurementsofthepopulationandauniformtaxonomicstandard,anddonotconsiderthepopulationcharacteristicsandintraspecificvariation.SoitisdifficulttomakeanintercontinentalcharopyhtebiostratigraphiccorrelationandcalibratetheK/PgboundaryinChina.InstudyofthePingyiBasin,ShandongProvince,bothtraditionsofidentificationfromChinaandEuropewerecombined.Forexample,PorocharaanluensisusedinChinawasinfactbelongedtothegenusFeistiellaaccordingtoobservingthesectionsofbasalplates.TheintraspecificvariationsPeckicharavarianswasrecognizedbasedonpopulationmeasurementandanalysis.TheabundantspeciesGobicharadesertaaroundtheCretaceous–PaleogeneboundaryisinfactayoungersynonymofMicrocharacristata.(Fig.1). Fig.2PaleobiogeographyofMicrocharacristataintheMaastrichtianandearlyPaleocene,showingitsEurasiandistribution.PaleogeographymodifiedfromBlakey(2006)withdataplottedonamapat65Ma.varss="图2.山东平邑盆地马斯特里赫特期至古新世早期Microcharacristata的地理分布，显示其欧亚分布。古地理图改自Blakey（2006），65Ma";if(ss=="")document.getElementById("d1").style.display="none"; Basedonaconcensusofidentificationstandard,anewbiozonationisproposedwhichencompassestwobiozonesbasedonspecieswithbroadpaleoecologicalrequirementsandaEurasiaticdistribution(Fig.2,3).EuropeanterrestrialCretaceous–Paleogeneboundaryismainlystudiedbasedoncharophytebiozonations,theresultscanalsobeusedintheresearchofChineseterrestrialCretaceous–Paleogeneboundary.ThesearetheMicrocharacristatabiozonestartinginthelatestCampanianandlastingatleastuntiltheearliestDanianandthePeckicharavariansbiozoneencompassingthelateDanian–earliestEocene.TheformercanbecorrelatedwithbiozonesestablishedbyGalbrunetal.(1993)andVicenteetal.(2015)andcalibratedtotheGPTS,andthelatterwascorrelatedwithPaleocenelargerforaminiferaintheNorthernPyrenees(Massieuxetal.,1981).Therefore,theCretaceous–PaleogeneboundaryfromthePingyiBasinwasproposedtobeinthefirstmember(uppersub-member)oftheBianqiaoFormation. Reference:Li,Sha,Wang,Qifei,Zhang,Haichun,Lu,Huinan,Martín-Closas,Carles*(2016)CharophytesfromtheCretaceous–PaleogenetransitioninthePingyiBasin(EasternChina)andtheirEurasiancorrelation.CretaceousResearch,59:179-200 Fig.3PaleoenvironmentalmodelssummarizingthepaleoecologicaldistributionofcharophyteflorasinthePingyiBasin(GuchengandBianqiaoFormations)duringtheMaastrichtianandPaleocene.
2017-05-25
-
Appendages of an early Cambrian trilobite support mandibulate affinities of trilobites
Recently,ZENGHan(PhDstudent)andhiscolleaguesfromtheNanjingInstituteofGeologyandPalaeontology,ChineseAcademyofSciencesdescribedindetailtheappendagesofanearlyCambriantrilobiteHongshiyanaspisyiliangensisZhang&LininZhangetal.,1980(Redlichiida,Metadoxididae)fromtheCambrianXiazhuangfossilassemblageatthesuburbanofKunming,Yunnan.Thisistheseventhtrilobitespecieswithcompleteappendagesdescribedandreconstructedintheworld,andthesecondoneinChinaafterEoredlichiaintermediafromtheChengjiangLagersttte.Thenewdatasupportsthemandibulateaffinitiesoftrilobites. TrilobitesareoneofthemostdiverseextinctgroupsofarthropodsthatinhabitedPaleozoicseasfromtheCambrianexplosiontotheend-Permianmassextinction(~520–250Ma).Sofar,morethan20,000trilobitespecieshavebeendiscovered.However,nearly99%trilobitespeciesarenamedbasedonmorphologyofexoskeletons,thesoftbodiesoftrilobitesarepoorlyknown.Inparticular,completewalkinglimbsoftrilobiteshaveonlybeenreconstructedinsixspeciesfromexceptionallypreservedfossildeposits.Thislimitedknowledgeofthetrilobitesoftanatomy,especiallyappendages,haslongconstrainedourunderstandingontheevolutionarypositionoftrilobitesonthearthropodtreeoflife. Owingtoincreasingnumbersofexceptionallywell-preservedarthropodsfromtheCambrianChengjiang(Yunnan,China)andtheBurgessShale(BritishColumbia,Canada)duringthelasttwodecades,theartiopods(meaningbearingacompletesetofsimilarappendages),amiscellaneousgroupofCambrianarthropodspossessingsimilarbodyplansandappendagestructureswithtrilobites,arewidelyacceptedastheclosestrelativesoftrilobites.However,noconsensushasbeenreachedontheclosestextantarthropodgroupoftrilobitesandartiopods,aseitherChelicerataorMandibulata. TheappendagesofH.yiliangensisexhibitthecommonarchitecturerevealedbyothertrilobitesandartiopodsbyconsistingofapairofuniramousantennaefollowedbyaseriesofpairedhomonomousbiramouslimbs.Theantennaeinholaspidindividualscompriseupto27spinouspodomeresandtheirontogenyoccursbylengtheningofthepodomeres.Thepost-antennalbiramouslimbsaresimilartothoseinothertrilobitesandartiopodsbyhavingasingle-segmentedprotopoditeandanendopoditecomprisingsevensegments,butpossessauniquewidetripartiteexopoditewithlongsetae. Appendagesoftrilobites,artiopodsandotherupperstem-groupeuarthropodsarecomparedandsummarized.TheH.yiliangensisappendageshighlightthehighmorphologicaldisparityofexopoditesandtheconservativenessofendopoditesintrilobitesandartiopods.Thismorphologicalpattern,togetherwithsimilarbodypatterningseenincrustaceansbutnotinchelicerates,supportsthemandibulateaffinitiesoftrilobitesandatleastsomeartiopods. ThisresearchwasfundedbytheNationalNaturalScienceFoundationofChina,theMinistryofScienceandTechnologyofChina,andtheChineseAcademyofSciences. Articleinformation:HanZeng,FangchenZhao*,ZongjunYin,MaoyanZhu.2017.AppendagesofanearlyCambrianmetadoxididtrilobitefromYunnan,SWChinasupportmandibulateaffinitiesoftrilobitesandartiopods.GeologicalMagazine:1–23.doi:10.1017/S0016756817000279.(*correspondingauthor) EarlyCambriantrilobiteHongshiyanaspisyiliangensispreservedwithcompleteappendages(ImagebyZengetal.) ReconstructionoflimbsofearlyCambriantrilobiteHongshiyanaspisyiliangensis(ImagebyZengetal.)
2017-05-23