Dynamic variation of Middle to Late Ordovician cephalopod provincialism in the northeastern peri-Gondwana region and its implications

Middle to Late Ordovician cephalopod occurrence data from South China and adjacent terranes in the northeastern peri-Gondwana region are used to define biogeographic provinces. Several multivariate methods are adopted for biogeographic analysis, including cluster analysis, non-metric multidimensional scaling and network analysis. During the Middle Ordovician, three biogeographic provinces in this region are recognized, the Australia, the North China–Tibet–Sibumasu (NTS) and the South China–Altun (SA) provinces. In the Late Ordovician, three provinces with modified geographic ranges may also be recognized, as the cephalopods of the Tibetan region and Sibumasu terrane changed significantly and accordingly they have been included with South China–Altun to form a South China–Tarim–Tibet–Sibumasu Province (STTS), while the other two Late Ordovician provinces are the Australia and the North China provinces. The dynamic variation of cephalopod provincialism in the northeastern peri-Gondwana region, may have been controlled by the changing palaeolatitude and differentiated movement of these plates or terranes from the Middle through Late Ordovician.