A new trilobite assemblage from the Pararaia bunyerooensis zone (Early Cambrian, South Australia) and its biostratigraphic significance

The Pararaia bunyerooensis Zone has been the most poorly understood of the Early Cambrian trilobite zones of South Australia. This was largely due to its supposed low diversity, consisting of the eponym and an indeterminate redlichiid, and its limited occurrence in the Flinders Ranges. This zone has only been previously recorded from the Mernmerna Formation at Bunyeroo Creek, and from the Third Plain Creek Member of the middle Mernmerna Formation at Wilkawillina Gorge (Jell in Bengtson et al. 1990). A recently discovered silicified trilobite fauna from the Mernmerna Formation at Angorichina in the eastern Flinders Ranges, South Australia, reveals the presence of a new assemblage from the Pararaia bunyerooensis Zone, including the eponymous species, Yorkella aff. australis, Eoredlichia sp., Redlichia sp., and new species of Wutingaspis and Yunnanocephalus (Paterson & Brock, in press). Trilobites of the Pararaia bunyerooensis Zone show a strong affinity with those from the Yu'anshan Member of the Heilinpu Formation in Chengjiang and Jinning counties, Yunnan Province, southwest China. The Pararaia bunyerooensis Zone is correlated with the Yunnanocephalus Assemblage subzone (upper Eoredlichia-Wutingaspis Zone) of the Chiungchussuan (=Qiongzhusian) Stage of China This, in turn, allows correlation with the early Botoman (Bergeroniellus micmacciformis-Erbiella Zone) of Siberia.1 page(s