Research On Tuzoia In The Cambrian, Guizhou

Large bivalved arthropods are widely distributed in the Cambrian sea, among them, Tuzoia is very common fossil in Cambrian strata of North America, Europe, Australia and China. The Tuzoia from Kaili Biota and Balang fauna are systematically studied here, increasing new information of this animal’s taxonomy, ecology and paleogeographic distribution.Several Burgess Shale-type Biotas are found in Strata of Cambrian series 2 and series 3 in Guizhou Province, Tuzoia is one of the most important fossil representatives in Balang fauna,Jianhe Biota and Kaili Biota. Tuzoia from Kaili Biota in Kaili Formation are recognized as one species- T. bispinosa here. Two species- T. retifera and T. sinensishe are found in Balang fauna in Balang Formation.Abundant complete and different stages of T. bispinosa specimens were collected in middle-upper part Kaili formation, Cambrian series 3, Guizhou province, these fossils provide crucial materials for study on its ontogenesis. Three stages of ontogeny for T. bispinosa: juvenile,youth, adult have been recognized and based on previously study and study in 168 relatively complete specimens and discerned resulting in six obvious morphologic stages that term early juvenile, late juvenile, early youth, late youth, early adult, and late adult stages, these studies reveal more information of this species’ development and evolution during its growth.Although small in quantities of Tuzoia in Balang Fauna, but they are obviously different with T. bispinosa in Kaili Biota, after systematically studied, two species are described here: T. retifera and T. sinensis.The free-swimming arthropod Tuzoia first discovered in Cambrian series 2, extended in Cambrian series 3 and flourishing, the evolutionary trend of its carapace can be concluded as follows: the size of carapace is bigger, cardinal process and the lateral ridge became stronger, and so many changes were all in an effort to live in marine environments.