Precambrian Animal Life: Probable Developmental and Adult Cnidarian Forms from Southwest China

Developmental Biology

Eric H. Davidson¹  Chia-Wei Li¹  Paola Oliveri¹  Stephen Q. Dornbos¹  Feng Gao¹  David J. Bottjer¹  Jun-Yuan Chen¹ 

[1] Nanjing Institute of Geology and Paleontology, Nanjing, 210008, China

关键词: cnidarian;    fossil;    Precambrian;    embryo;   

DOI  :  10.1006/dbio.2002.0714

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

TheevolutionarydivergenceofcnidarianandbilaterianlineagesfromtheirremotemetazoanancestoroccurredatanunknowndepthintimebeforetheCambrian,sincecrowngrouprepresentativesofeacharefoundinLowerCambrianfossilassemblages.Wereporthereavarietyofputativeembryonic,larval,andadultmicrofossilsderivingfromPrecambrianphosphoritedepositsofSouthwestChina,whichmaypredatetheCambrianradiationby25–45millionyears.Thesearemostprobablyofcnidarianaffinity.Largenumbersoffossilizedearlyplanula-likelarvaewereobservedunderthemicroscopeinsections.Thoughseveralformsarerepresented,themajoritydisplayremarkableconformity,whichisinconsistentwiththealternativethattheyareartifactualmineralinclusions.Someofthesefossilsarepreservedinsuchhighresolutionthatindividualcellscanbediscerned.Weconfirmindetailanearlierreportofthepresenceinthesamedepositsoftabulates,anextinctcrowngroupanthozoanform.Othersectionsrevealstructuresthatmostcloselyresemblesectionsofbasalmoderncorals.Alargenumberoffossilssimilartomodernhydrozoangastrulaewerealsoobserved.Theseagaindisplayedgreatmorphologicalconsistency.Thoughonlyasingleexampleisavailable,amicroscopicanimalremarkablysimilartoamodernadulthydrozoanisalsopresented.Takentogether,thenewobservationsreportedinthispaperindicatetheexistenceofadiverseandalreadydifferentiatedcnidarianfauna,longbeforetheCambrianevolutionaryevent.Itfollowsthatatleaststemgroupbilateriansmustalsohavebeenpresentatthistime.

【 授权许可】

Unknown