Middle Ordovician harknessellid brachiopods (Dalmanellidina) from the Mediterranean margin of Gondwana

Bulletin of geosciences

Jiménez-Sánchez A¹  Gutiérrez-Marco JC¹  Villas E¹  Colmenar J¹  Reyes-Abril J¹ 

关键词: Ordovician;    brachiopods;    Orthida;    Iberian Peninsula;    Spain;    Gondwana;   

DOI  :  

来源: Czech Geological Survey

【 摘 要 】

ThefamilyHarknessellidaeBancroft,1928(Orthida,Dalmanellidina)wasdesignedtoembraceanassemblageofspeciesreferredpreviouslytoHarknessellaReed,1917,andincludedfivegeneraknownmainlyfromtheMiddleandUpperOrdovicianofEngland.Herein,wesuggestreassigningtothisfamilythegenusCacemiaMitchell,1974,widespreadinthemiddleDarriwilian(upperMiddleOrdovician)oftheIberianandArmoricanmassifs.Sinceitsdesignation,Cacemiawasplacedamongthedalmanellidinheterorthids,inspiteofitsstronglymucronatehingeline,whichistotallyunknownwithinthisMediterraneanfamily.AnewharknessellidhasbeenidentifiedfromtheupperDarriwilianbedsoftheCentralIberianZone(CentralSpain):IsabelellafascicostellataReyes-Abrilnbsp;Villasgen.etsp.nov.ItissimilartoHorderleyellaBancroft,1928foritscoarselyfascicostellateradialornamentationandobtusecardinalangles,althoughitsconvexoplanetoconvexoconcaveprofileallowsdiscriminationfromthetypicallydorsibiconvexHorderleyella.AphylogeneticanalysisofthefamilyplacesbothCacemiaandIsabelellainbasalpositionsoftheirclades,whichfitswiththeirearlystratigraphicrecord.Basedonourstudy,thefamilyHarknessellidaeappearstohaveoriginatedinthehighlatitudeMediterraneanmarginsofGondwanaduringpre-Darriwiliantimes,beforethedetachmentofAvaloniafromGondwana.ThefamilyreacheditshighestdiversificationinAvaloniathroughouttheLateOrdovician,keepingconnectionswiththeMediterraneanandProto-AndeanmarginsofGondwana,aswellaswiththemid-latitudepalaeocontinentsofBalticaandSouthChina.

【 授权许可】

Unknown