Uppermost Ordovician bivalves from the Prague Basin (Hirnantian, Perunica, Bohemia)

Bulletin of geosciences

Steinová M¹  Kříž J¹ 

关键词: Bivalvia;    uppermost Ordovician;    late Hirnantian;    systematics;    palaeoecology;    Perunica;    Prague Basin;    Bohemia;   

DOI  :  

来源: Czech Geological Survey

【 摘 要 】

Twelvespecies(fournew)and9generaofbivalvesaredescribedfromtheuppermostHirnantian,UpperOrdovicianofthePragueBasin,Bohemia:Praenuculadispar(Barrande,1881),Praenuculaabruptasp.nov.,Sluhakosoviensis(Barrande,1881),Nuculitesaff.planulatusConrad,1841,Myoplusiacontrastans(Barrande,1881),Myoplusiaobtusa(Barrande,1881),Myoplusiasp.,Metapalaeoneilodromonsp.nov.,Praeledacompar(Barrande,1881),Mytilarcamarekisp.nov.,Modiolopsispragensissp.nov.,and?Sphenoliumcf.parallelumUlrich,1894.Fromthecoarse,stormgeneratedsandstonesrepresentingtheadditionalregressiveevent,whentheshelfwaschannelled,andcoarsematerialtransportedfromtheshoreinthelateHirnantian,thelowdiversified,almostmonospecificModiolopsispragensisCommunity,oftheModiolopsisCommunityGroup,wasdescribed.Itindicatesrestrictedlivingconditions.11bivalvespeciesform,togetherwith25speciesofbrachiopods,5speciesofgastropods,andundescribedconulariids,hexactinellids,trepostomatebryozoans,annelids,hyolithids,orthoconenautiloids,rareostracods,phyllocarids,blastoids,cystoids,crinoids,dendroids,graptolites,andchlorophytes(receptaculitids)theredefinedHirnantiasagittifera–SluhakosoviensisCommunity.ItrepresentsthemostdiversifiedcommunityoftheHirnantiaCommunityGroupknownintheWorld.WesupposethattheHirnantiasagittifera–SluhakosoviensisCommunityoccupiedthewell-ventilatedenvironmentofthesoftbottomcarbonatesiltswithhighorganiccontent.Thecommunitywasmostprobablyautochthonous,withminimaltransportasisindicatedbythecommonpreservationofshellswithconjoinedvalves(articulatebrachiopods,semi-infaunalbivalveMytilarcamareki,andinfaunalbivalves).ThebivalvesMytilarcamarekiandMetapalaeoneilodromonsp.nov.,Nuculitesaff.planulatus,and?Sphenoliumcf.parallelummayhaveoriginatedintheBalticacarbonateplatformsandtheequatorialregionsofAvaloniaandLaurentiaandsupporttheideasaboutthepositionoftheKosovProvinceinthetemperate-to-subtropicalzone(between30°to45°S).FortheanalogousandhomologouscommunitieswedescribedtheHirnantiaCommunityGroupasasubstitutefortheterm“Hirnantiafauna”.TheHirnantiaCommunityGroupwasmostprobablyextendingfromthecircumpolarsphereintothetemperatetotropicalzonesinproximitytothecarbonateplatforms.InBohemiaandelsewhereitoccursjustafewmetresbelowtheOrdovician-SilurianboundaryandrepresentstheevidenceoftheenvironmentalrecoveryduringtheuppermostOrdoviciantransgressionfollowingtheUpperOrdovicianglobalglaciation

【 授权许可】

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