Cisuralian and Guadalupian global paleobiogeography of fusulinids in response to tectonics, ocean circulation and climate change
Abstract During the Permian, major icehouse-greenhouse climate shifts and tectonic reconfiguration had important biogeographic implications, especially for climate-sensitive organisms such as fusulinids. Here we present multivariate methods on a global fusulinid species dataset including 1546 species from 58 localities in the Early (Asselian, Sakmarian, Artinskian and Kungurian) and Middle (Roadian, Wordian and Capitanian) Permian. Our results show that fusulinid global provincialism was high in the Asselian, Sakmarian, and Artinskian, driven by the development of multiple fusulinid bioregions in and near the Tethys Ocean. During the Asselian, Uralian sites and nearby regions of western Tethys were distinct from eastern Tethys, while stations in Arctic Russia and Norway formed a separate Boreal bioregion. Tectonic closure of the oceanic gateway in the southern Urals resulted in progressive isolation of the Uralian and Boreal bioregions during the Sakmarian and Artinskian and their ultimate disappearance by the Kungurian. Climate warming likely was the most important control on the Sakmarian formation of the distinct peri-Gondwana bioregion, because its development coincided with deglaciation following the Late Paleozoic Ice Age but preceded the separation of the Cimmerian terranes from northern margin of Gondwana. On the other hand, northward movement of the Cimmerian blocks following Artinskian-Kungurian rifting ultimately led to the merger of the peri-Gondwanan bioregion with tropical Tethyan faunas, resulting in lower provincialism in the Guadalupian and minimal faunal differentiation across Tethys. In contrast, faunal similarity between Tethys and eastern Panthalassa (the McCloud region and southwestern United States) was higher in the Asselian-Artinskian but decreased in the Kungurian and Middle Permian, perhaps as the result of sluggish ocean circulation following the warming episode of Late Paleozoic deglaciation.