Preliminary Study On Large Bivalved Arthropods Animals In "Tsinghsutung Formation" At Balang Village,Jianhe County,Guizhou Province

Large bivalved arthropods are widely distributed in the Cambrian sea,and are very common fossil in Cambrian strata of North America,Australia and China.Jianhe Biota,with soft body fossils,is in middle-upper part of “Tsinghsutung Formation”which covered by Kaili Formation.Large bivalved arthropods plays an important role in Arthropod of the biota which includes 6 genera large bivalved arthropods.This thesis describes 8 species,including 2 uncertain species,belong to 6 genera of large bivalved arthropods in Jianhe Biota: Tuzoia Walcott,1912(Tuzoia jianheensis and T.bispinosa),Isoxys Walcott,1890(Isoxys auritus and I.wudingensis),possible Branchiocaris Briggs,1976(?Branchiocaris sp.),Canadaspis Novozhilov in Orlov,1960(Canadaspis laevigate),Occacaris Hou,1999(Occacaris magnus)and Waptia Walcott,1912(? Waptia sp.).Large bivalved arthropods of Jianhe Biota in “Tsinghsutung Formation” have a low diversity but a relatively high disparity of genera,and plays an important part of the biota.Based on the number of individuals,Tuzoia constitutes about 88% of the total number of organisms recovered from the Jianhe Biota.This makes them the most abundant large bivalved arthropods of the Jianhe Biota.Isoxys occupying 6% of the total number of organisms is the second most abundant large bivalved arthropods of the Jianhe Biota.The sequence of the other large bivalved arthropods is Branchiocaris,Canadaspis,Waptia and Occacaris,and most of the genera continue to the Kaili Formation.Composition characteristics of large bivalved arthropods in Jianhe Biota are similar to the Kaili Biota which dominanted Tuzoia,Occacaris and Canadaspis,however,differs from both Burgess Shale Biota which gives priority to Canadaspis and Chengjiang Biota which gives priority to Isoxys.The thesis researches large bivalved arthropods in Jianhe Biota for the first time.It supplies the paleontologic information,discusses the composition features and compares with other Burgess shale type biota around the world.The study provides new material of composition features of Jianhe Biota,and contributes to the study of Cambrian explosion,especially in the continuity of the large bivalved arthropods evolution of Cambrian Series 3 in Guizhou area.