Moulting Behavior Of Trilobite From The Cambrian Kaili Formation In Jianhe,Guizhou

Mainly dominated by greyish-green silty shale,argillaceous limestone and limestone in eastern Guizhou,the Kaili Formation,Cambrian Series 2 Stage 4 and Miaolingian Series Wuliuan Stage,yielded abundant trilobite fossils and preserved a large amount of trilobite moulting specimens,providing valuable materials for revealing the trilobite moulting behavior.Based on massive trilobite moulting specimens from Kaili Formation,we conducted a comprehensive discussion on the trilobite moulting configurations,moulting method and moulting processes.And herein the moulting behavior of Trilobite Ptychopariida: Xingrenaspis xingrenensis,Eosoptychopara guizhouensis and Kailiella angusta have first been studied in detail.Despite previous study on moulting of Trilobite Corynexochida:Oryctocephalus indicus,Olenoides Paraptus and Bathynotus Kueichouensis,the newly collected fossil materials herein certainly provide necessary supplement for the study of its moulting behavior.On the basis of comparison and analysis on various moulting configurations of trilobites attributed to 6 genera,6 species,it was found that the diversity and main modes of moulting configurations in molting were largely subject to structure characteristics,ontogenetic stage,relative size and environment.However,apparent cause-effect relationship was not shown in the phylogenetic relationship and taxonomic position among species.For example,despite belonging to different species,O.indicus and E.guizhouensis shared certain similarities,on the contrary,due to the structural differences among species and the different types of moulting cephalic suture,great similarity and some differences in moulting method existed between X.xingrenensis and E.guizhouensi,both of which were close in taxonomic position.By preliminarily reducing the moluting process of O.indicus,E.guizhouensis and X.xingrenensis,various effects on the preservation of exuviate caused by different choices during moulting were further revealed.With ample trilobite moulting specimens,it was found that the moulting method of trilobite all followed Olenids-moulting,in which the moulting process was fulfilled through the splitting of cephalic suture,differing from Salter-moulting and Harpes-moulting,in both of which moulting was completed by the break between cephalic shield and pygidial shield and by marginal cephalic suture along the anterolateral margin respectively.