Sibling echinoderm taxa on isolated Ordovician continents: Problem of center of origin

Bulletin of geosciences

Rozhnov SV¹ 

关键词: Ordovician;    echinoderms;    sibling taxa;    biogeography;    Baltica;    Laurentia;    Gondwana;   

DOI  :  

来源: Czech Geological Survey

【 摘 要 】

MorphologicallysimilarechinodermgeneraaremostlyknownfromtheOrdovicianoftwoisolatedcontinents,BalticaandLaurentia,althoughtheselandmasseswerestrictlyisolatedbiogeographicallybytheIapetusOceanandhaddifferentclimatesduringtheEarlyandMiddleOrdovician.ThemorphologicalcharactersofmostoftheseechinodermgeneraexcludethepossibilitythatBalticgeneraevolvedfromLaurentianformsorviceversaandsuggestthattheircommonancestralgroupwasfromadifferentregion.Iproposedtonamesuchgenera‘siblinggenera’,ortwingenerabyanalogywithsiblingspecies.Eocrinoidsiblinggeneraarerepresentativesofthecryptocrinitid-rhipidocystidclade.BalticParacryptocrinitesandCryptocrinitesaresiblinggeneraofLaurentianColumbocystis,SpringerocystisandFoerstecystis,BalticRhipidocystisisasiblinggenusofLaurentianMandalacystisandBalticNeorhipidocystisissiblinggenusofLaurentianBatherocystis.ItisassumedthatNorthAmericanplaticystidparacrinoids,cryptocrinidandrhipidocystideocrinoidsevolvedfromacommonancestraleocrinoid,similartoParacryptocrinites.SiblinggeneraarealsoknownamongotherOrdovicianechinoderms,forexample,crinoids(hybocrinids),edrioasteroids(edrioblastoids)andrhombiferans.SomegeneramigratedfromBalticatoLaurentiaandviceversa.ThetemperatewarmwaterseasofeasternGondwanainthenorthernChina-Australianregionwereapossiblebiogeographicalcenteroforigin,diversificationordistributionofLaurentianandBalticsiblinggenera.BiogeographicalanalysisofBalticechinodermsshowsthattheBalticRegioncouldbeviewedasa‘museum’or‘storehouse’formanyofthem,theyimmigratedandsurvivedthereforsomeconsiderabletime,ratherthena‘cradle’,wheretheyaroseandfromwheretheymigratedtoothercontinents.

【 授权许可】

Unknown