Bivalves from the Middle Ordovician Šárka Formation (Prague Basin, Czech Republic)

Bulletin of geosciences

Polechová M¹ 

关键词: bivalves;    Middle Ordovician;    Perunica;    Bohemia;    systematics;    palaeoecology;    palaeobiogeography;   

DOI  :  

来源: Czech Geological Survey

【 摘 要 】

ArichbivalvefaunafromtheMiddleOrdovician(ŠárkaFormation,earlyandmidDarriwilian)ofBohemiashowscloseaffinitiestoMiddleOrdovicianbivalvesfromSpain(IberianPeninsula)andFrance(ArmoricanMassif).Twelvespeciesandninegenera(onenew)aredescribed:Praenuculaapplanans(Barrande,1881),Praenuculabohemica(Barrande,1881),Praenuculadispar(Barrande,1881),Concavodontaponderata(Barrande,1881),Pseudocyrtodontaala(Barrande,1881),Pseudocyrtodontaincola(Barrande,1881),Tatulapetulagen.etsp.nov.,RedoniadeshayesiRouault,1851,BabinkaprimaBarrande,1881,Coxiconchiabritannica(Rouault,1851),andtheoldestpteriomorphidsinthePragueBasinModiolopsissp.andCyrtodontasp.Ctenodonta,widelyusedascumulativenameforallpraenuculids,wasnotrecordedintheMiddleOrdovicianofBohemia.RemarksonthecharactersoftheProtobranchiashellarediscussed,thevalueoftheorientationoftheteethtotheumbooroutfromtheumboforhighersystematichasbeenoverestimatedinthepast.AccessorymusclescarsintheProtobranchiahelptomovewithfoot,notonlybyretractionandprotractionbutalsobyelevation;someofthemholdavisceralsac.TheRecentProtobranchiamostlyshowsimplertypeoftaxodontteethincomparisonwiththeOrdovicianProtobranchia.Palaeoecologicalaspectsofallthespeciesareshown,infaunalburrowersdominateinthelithofaciesoftheblackshalesoftheŠárkaFormation.Thebivalveassociationisdominatednumericallybyheterodonts,subdominantareseveralspeciesofprotobranchsandtwopteriomorphids.ThepalaeogeographicdistributionoftheMiddleOrdovicianbivalvesisdiscussed.SomeoftheMiddleOrdovicianbivalvesarewidelydistributed,theyreachBalticaandalsotheLaurentianmarginsandprobablyhadtohaveplanktotrophiclarvae.Clearpreferenceoftheheterodontsforhighlatitudeisconfirmedbythedominantheterodonts(sixspecies)inthebivalveassociationoftheMiddleOrdovicianŠárkaFormation.

【 授权许可】

Unknown