Sphenopsida And Filicinae Fossils With In Situ Spores From The Permian Of Yongchang,Gansu

The Permian is an important development period in the Earth history.This period has many kinds of plant contained Articulatae,Lycophytes,Filicophytina,Pteridospermae and is significance to study the paleogeographic distribution and systematic paleobotany evolution.Plant fossils are the products of geological history.They are irreplaceable in the study of plant origin,evolution,and rebuilding environment.The Permian in Yongchang,Gansu contains abundant sporopollen and plant fossils.These materials provide a good contrast material for the study of the Late Paleozoic plant in the future.Besides,these fossils are significance for the study of the species diversity of Sphenophyllum and Cyathocarpus in the study area,plant paleogeography,the Late Paleozoic Yongchang flora,the relative position of the paleoplates,and the compositions exchange among North China,South China and Alashan floras.The fossil materials were collected from in the Cisuralian Taiyuan and Shanxi Formation of Yongchang,Gansu Province.By the macromorphological comparison and cluster analysis,the macrofossils(leaves and reproductive organs of Sphenopsida and Filicinae)were systematically studied.In situ spores of Cyathocarpus were obtained by analysis in the lab.Spore's microstructures were studied by optical and scanning electron microscopy.In addition,through the statistics of the fossil records in the late Paleozoic,the paleogeography of Cyathocarpus and Sphenophyllum(origin,evolution and geologic change,etc.)was discussed.In the present study,we reported 2 genera and 5 species as Sphenopsida: Sphenophyllum spathulatum?S.thonii?S.kawasakii?S.oblongifolium and Bowmanites yongchangensis sp.nov.,including nutrition and reproductive organs.Based on these new materials,we studied the characters of S.kawasakii and S.oblongifolium and revised their species diagnosis.A new species of Bowmanites was reported as Bowmanites yongchangensis sp.nov.Its sporangium and sporophyll were described in detail.In addition,we studied some sterile and fertile fronds from Shanxi Formation,Cisuralian in the study area in detailed.1 genus 1 new species was identified: Cyathocarpus yongchangensis sp.nov.In particular,synangium and in situ spores were analyzed in the lab.Data showed that the synangium of this species contained four and five radially arranged pedicellate sporangia.The spores of this plant were small,between 21 and 30 ?m,monolete and microgranulate with no visible annule.These spore masses and spores in situ of this genus were described in detail at the first time as a component of the Cathaysian flora,which provided some valuable microstructure taxonomic information.Based on the fossil records,we analyzed the diversity,origin and emigration path of Sphenophyllum and Cyathocarpus in the study area.The two genera reported in the Cisuralian from the study area showed a high diversity and both existed in Euramerican and Cathaysia floras in Late Paleozoic,which showed the close communication these floras.Besides,through comparing and discussing the synangium,palynology and leaf shape characteristic with different genera,it was inferred that Cyathocarpus,Zhutheca,Danaea may have a close genetic relationship and their evolution order is Cyathocarpus-Zhutheca-Danaea.