A review of Silurian fishes from Yunnan, China and related biostratigraphy

The Silurian fishes from Yunnan, China are characterized by early occurrence and diversification of jawed vertebrates, e.g., placoderms and osteichthyans in particular. They have provided critical data in the quest for early vertebrate evolution and reliable palaeoichthyological evidence for regional stratigraphic issues, exemplified by the subdivision and correlation of the Silurian fish-bearing strata, and the definition of the Silurian–Devonian Boundary (SDB) in Yunnan. Here we summarize the Silurian fishes known in Yunnan so far, and classify them into two vertebrate faunas (Xiaoxiang and Xitun faunas) and three vertebrate assemblages (Yangtze, Hongmiao, and Liaojiaoshan assemblages). Based on this updated Silurian vertebrate database that is coupled with conodont records and chemostratigraphic results, the exact level of the SDB in East Yunnan is placed between the Yulungssu Formation and the Xishancun Formation. In addition, the Silurian fish-bearing marine red beds in Qujing (Yunnan) are assigned to the Late Ludlow and can be correlated with the redefined Xiaoxi Formation in Xiushan (Chongqing) and Zhangjiajie (Hunan).