A New Zosterophyll Plant,Ramoferis gen.nov.,from the Posongchong Formation of Lower Devonian (Pragian) of Southeastern Yunnan,China  

作　　者：HAO Shougang XUE Jinzhuang 

机构地区：[1]Key Laboratory of Orogenic Belts and Crustal Evolution,School of Earth and Space Sciences,Peking University,Beijing 100871,China

出　　处：《Acta Geologica Sinica(English Edition)》2011年第4期765-776,共12页地质学报（英文版）

基　　金：supported by NSFC(Nos.40802003 and 40830211)

摘　　要：A new genus and species,Ramoferis amalia gen.et sp.nov.,is described from the Early Devonian（Pragian）Posongchong Formation,Wenshan district of southeastern Yunnan,China.This plant has isodichotomous major axes,which also divide anisotomously distally to produce closely spaced lateral branches,often within fertile regions.The stalked round to reniform sporangia,borne laterally and spirally over several levels of branches,are distantly to moderately spaced or aggregated into distinct spikes.The stalks increase in width from the base to the sporangial junction resulting in a gradual transition between sporangium and stalk.Comparison with known zosterophylls shows that this plant is most similar to the genera Zosterophyllum and Wenshania,differing in the character combinations of sporangial shape,sporangium/stalk junction,stalk dimensions and orientation,and especially in both sterile and fertile branchlets being borne within the fertile zone.In addition,the observation and comparison indicate distinct variety in structure of sporangial border and suggest that the two-layered sporangium wall characterized by outer anticlinal layer and inner periclinal layer might represent potential synapomorphies,while the different dehiscence mechanism is an autapomorphy for each taxon in zosterophylls.A new genus and species,Ramoferis amalia gen.et sp.nov.,is described from the Early Devonian（Pragian）Posongchong Formation,Wenshan district of southeastern Yunnan,China.This plant has isodichotomous major axes,which also divide anisotomously distally to produce closely spaced lateral branches,often within fertile regions.The stalked round to reniform sporangia,borne laterally and spirally over several levels of branches,are distantly to moderately spaced or aggregated into distinct spikes.The stalks increase in width from the base to the sporangial junction resulting in a gradual transition between sporangium and stalk.Comparison with known zosterophylls shows that this plant is most similar to the genera Zosterophyllum and Wenshania,differing in the character combinations of sporangial shape,sporangium/stalk junction,stalk dimensions and orientation,and especially in both sterile and fertile branchlets being borne within the fertile zone.In addition,the observation and comparison indicate distinct variety in structure of sporangial border and suggest that the two-layered sporangium wall characterized by outer anticlinal layer and inner periclinal layer might represent potential synapomorphies,while the different dehiscence mechanism is an autapomorphy for each taxon in zosterophylls.

关 键 词：zosterophyll Early Devonian Posongchong Flora YUNNAN 

分 类 号：Q915.862[天文地球—古生物学与地层学] P534.44[生物学—古生物学]