Description and classification of Late Triassic Neritimorpha (Gastropoda, Mollusca) from the St Cassian Formation, Italian Alps

Bulletin of geosciences

Bandel K¹ 

关键词: Gastropoda;    Neritimorpha;    Triassic;    Tethys;    Italy;    Jordan;    new taxa (fossil;    living);   

DOI  :  

来源: Czech Geological Survey

【 摘 要 】

NeritopsisrepresentstheonlysurvivinggenusofanancientgroupoftheNeritimorphathathasnointernaldissolutionofitsshellwalls.Whilethetwoknownlivingspecieshavelecithotrophicearlydevelopmentwithoutlarvalshell,Neritopsisaqabaensisn.sp.fromtheGulfofAqaba,Jordan,hasaplanktotrophicveliger.TheselivingspeciesofthegenusdifferintheirprotoconchshapeaswellasteleoconchmorphologyandornamentfromtheTriassicspeciesthatcanbeconsideredrelatedtoNeritopsis.NeritopsidaewiththemodernNeritopsinaeisdistinguishedfromtheTriassicCassianopsinaen.subfam.basedonthegenusCassianopsisn.gen.withthreespeciesbyfeaturesoftheirprotoconchaswellasthedifferentcharactersoftheoperculum.Zardiniopsisn.gen.differsfromthesebyhighershellshapeandasmallermorecomplexlyornamentedprotoconch.Fossariopsishasamoreangularshellshape.Colubrellopsinaen.subfam.withColubrellopsisn.gen.resemblesCassianopsisn.gen.inrespecttoprotoconchandfeaturesoftheapertureoftheteleoconch,buttheformerhasroundedwhorlsandanornamentofaxialribs.AmongtheFedaiellidaen.fam.withsmoothshellstwospeciesofFedaiellaareredefined.ThecharactersoftheinnerlipoftheirapertureconnectthemwiththeNeritopsidae,whereastheoperculumintheFedaiellidaewithconcentricstructureontheoutsidedistinguishesthemfromneritopsids.IndistinctiontothegroupsoftheNeritopsoideamembersoftheDephinulopsidaehaveasmoothinnerlipoftheaperture.HereDelphinulopsinaeandPlatychilininaen.subfam.differfromeachotherintheshapeandornamentoftheirteleoconch.Schwardtopsisn.gen.resemblesajuvenileDelphinulopsisgrowntoalargersize.ThelargeconcavecallusoftheinnerlipandalmostopencoilingdefinesDelphinulopsis.Rowsofnodes,lowinitialshellandrapidgrowthinshelldiametertoanalmostlimpetshapecharacterisesPlatychilina,andlamellargrowthincrementsonanalmostlimpet-likeshellwithflatinitialpartispresentinMarmolatella.ThePalaeonaricidaen.fam.containstwospeciesofPalaeonarica,whichhaveaNerita-likeshellwithsimpleaperture.TheNaticopsidaeoftheCarboniferousandPermianhasitscontinuationintheAmpezzonaticopsinaen.subfam.oftheTriassic,beingconnectedtoeachotherbythesinuousornamentofribsontheirlarvalshells.Thegeneraaredistinguishedbyteleoconchshapeanddifferencesintheornamentoftheirlarvalshell.Ampezzonaticopsisn.gen.haswhorlswellseparatedbydeepsutures,Cortinaticopsisn.gen.hasasimpleapertureandacalluscoveringtheumbilicus.TheHologyrinaen.subfam.withHologyrahavearidgeinthecolumellarfurrowandanoperculumthatresemblesthatattributedtoCarboniferousNaticopsis.Theirprotoconchhasacharacteristicchevronornamentonitslarvalwhorls.

【 授权许可】

Unknown