The Late Triassic Podozamites And Ferganiella From Lufeng,Yunnan And Their Palaeoecology

The Late Triassic flora in the Yipinglang Coalfield of Lufeng County,Yunnan Province is characterised by Dictyophyllum-Clathropteris assemblage with diverse Bennetittales,which represents the typical South China Late Triassic Flora.The study of the Yipinglang flora could be traced back to the beginning of the 20th century.Podozamitales are the most common elements in the flora,but their systematic affinities are still controversially debated.Based on detailed examinations of 1840 specimens from the Upper Triassic Pujiacun Formation,Ganhaizi Formation and Shezi Formation in the Yipinglang Coalfield,eight species of three genera have been recognised,i.e.Podozamites(1417 specimens,P.distans(Presl)Braun,P.schenkii Heer,P.paralanceolatas Wu and P.austro-sinensis Wu),Ferganiella(407 specimens,F.paucinervis Li and F.podozamioides Lih)and Cycadocarpidium(16 specimens,C.swabii Nathorst and C.erdmannii Nathorst).The tempo-spatial distribution of Podozamitales in the Mesozoic of China indicates that it firstly appeared during the Early Triassic in northeastern China,then gradually increased and reached its maximum in both diversity and distribution during the Late Triassic in both southern and northern China;since the beginning of Middle Jurassic it was reduced gradually in both diversity and distribution,and completely disappeared from the Mesozoic of China since the Late Cretaceous.The tempo-spatial distribution of Podozamitales is likely the result of combined effects of the palaeoclimatic and palaeogeographic changes.Five functional feeding groups(FFGs),including marginal feeding,hole feeding,surface feeding,piercing-and-sucking and mining were observed in the Podozamites and Ferganiella leaves of the flora.Statistic analysis shows that 1.2%of Podozamites leaves and 3.69%of Ferganiella leaves have been consumed.DT96(0.21%of all Podozamites)and DT012(0.07%of all Podozamites)were found in Podozamites distans(Presl)Braun.DT128(0.07%of all Podozamites)were found in Podozamites austro-sinensis Wu.DT31(0.07%of all Podozamites)were found in Podozamites schenkii Heer.DT8(0.14%of all Podozamites),DT96(0.07%of all Podozamites),and DT210(0.42%of all Podozamites)were found in Podozamites sp..DT8(1.47%of all Ferganiella),DTI 5(0.25%of all Ferganiella),DT94(0.98%of all Ferganiella),DT128(0.25%of all Ferganiella),and DT214(0.74%of all Ferganiella)were found in Ferganiella podozamioides Lih.These feeding damage traces indicate the complicated interactions between Podozamitales and herbivorous insects during the Late Triassic in Lufeng.This paper presents direct fossil evidence for the interactions between plants and herbivorous arthropods during the Late Triassic period,and is helpful in assessing the complexity of the early terrestrial ecosystems.