Trilobites From The Cambrian "Tsinghsutung Formation" At Balang Village,Jianhe County,Guizhou Province

The Cambrian “Tsinghsutung Formation” at the Songshan section near Balang Village,Jianhe County,Guizhou Province is dominated by limestones with interbedded mudstone and Jianhe Biota which is richly fossiliferous with soft-bodied fossils was discovered in the middle-upper part of the formation.In this Biota,Sponge,“Worms”,Brachipods,Cnidarians,Arthropods,Echinodermata,Wiwaxia and algae are mainly-found fossils in which trilobite is the most abundant tax.Additionally,8000 speciemens referred to 3 phyla(Redlichiida,Ptychopariida and Corynexochida)have collected from the “Tsinghsutung Formation”.After a work in identifying 5000 speciemens of trilobite,the preliminary investigation in systematic was mainly accomplished in this thesis,especially in record and supplementary description of several specified taxon.Besides,the other work in component,evolution in predominated trilobites and biostratigraphy have also been discussed.There are 15 genera of trilobites described in the thesis: 7 genera of Corynexochida,6 genera of Ptychopariida,1 genera of Redlichiida and 1 genera(Burlingia)of uncertain order.Oryctocephalid trilobite is the most abundant taxa and the most important in stratigraphic research and 4 genera were identified: Protoryctocephalus,Duyunaspis,Arthricocephalus and Oryctocarella.Besides,Balangcunaspis ? Mufushania ? Eosoptychoparia ? Yuehsienszella ?Arthricocephalus?Oryctocarella?Panxinella?Dinesus were newly-discovered genera,which enriches the he trilobite component of this unit.Among them,Arthricocephalus,Oryctocarella and Duyunaspis range downward to the underlying Palang Formation” whlie Protoryctocephalus,Olenoides,Eosoptychoparia,Nangaops and Burlingia range upward to the overlying Kaili Formation.The “Tsinghsutung Formation” is obviously a layer with transitional feature in trilobite component.These trilobites from the Cambrian “Tsinghsutung Formation” at Songshan section plays a role in trlobite evolution and biostratigraphic division.Firstly,ptychopariid trilobites from the middle-upper part of the “Tsinghsutung Formation” throws new light on the evolution of the taxa.As it was reported,ptychopariid trilobites develope from 1 genus in the Palang Formation to 30 genera in Kaili Formation and 6 genera in the “Tsinghsutung Formation”.The phenomenon implicates that ptychopariid trilobites have a tendency of radiation from Cambrian Series 2 to Series 3,especially in Series 3.Furthermore,Burlingia balangensis is the most primitive specie of the genus,all species of which have formed a evolution from Cambrian Agae 4 to Age 6(Drumian).The evolution chain is also a reference for biostratigraphic division.Lastly,Protoryctocephalus arcticus and Arthricocephalus chauveaui are important biological bases for estabilsing the trilobite zones of the “Tsinghsutung Formation”.These trilobites provide a vew data for the biostratigraphic study of Cambrian Stage 4(Duyunian)...