1 Nanjing Institute of Geology and Palaeontology， Chinese Academy of Sciences， Nanjing210008，Jiangsu
2 Australian Museum， 6 College Street， Sydney， NSW 2010， Australia
3 Xian Institute of Geology and Mineral Resources， Xian710054，Shaanxi
Trilobite evidence indicates that all the plates and most of the terranes in China exhibit a close biogeographic link and may have formed part of the eastern PeriGondwana during the Ordovician， except for the Altay Terrane of the Northern Xinjiang Autonomous Region and the ErgenHinggan Terrane of the Hinggan Region， where trilobite faunas show a strong affinity with those of Siberia and Laurentia. Synthetic analyses based largely on the platform/inner shelf trilobite faunas suggest that the Chinese eastern PeriGondwanan plates and terranes may have belonged to a single biogeographic province during the Tremadocian(Tremadoc)and the late KatianHirnantian(Ashgill)， but may be divided into two subprovinces during the Floianearly Katian(ArenigCaradoc): One consists of South China， Tarim and Annamia， and the other may include North China， Sibumasu， southern Tibet， TianshanBeishan and possibly Hainan. However， the deepwater facies trilobites of the relevant Chinese biogeographic units had progressively become more unified from the middle Darriwilian to the early Katian(Llanvirn to Caradoc)before the subprovinces eventually broke down by the late Katian(Ashgill). Therefore，the exchange of genus and species between deepwater facies animal assemblages and the onset， development and complishment of the process were obviously prior to those of the trilobites in shallow water.
