Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China

Tuzoia is a large bivalved arthropod having a wide geographic distribution in the strata of the Cambrian Series 2 and 3. One species, Tuzoia bispinosa, is known from abundant material in the Kaili Biota (Cambrian Series 3, Stage 5). Based on 168 specimens from near Balang Village, Jianhe County, Guizhou Province, China, six ontogenetic stages of this species can be distinguished. In addition, the material provides information pertinent to interpreting the taphonomic history of T. bispinosa.