ABSTRACT
Palaeobiogeographic evolution of Permian brachiopods was investigated based on a quantitative analysis proceeded from the data base which collected 28,000 records of brachiopod taxa from 4S0 stratigraphic levels of 289 localities all over the world. The Otsuka coefficient was selected as the best quantitative indices in revealing fauna] affiliation. The biogeographic affinities of coeval brachiopod faunas can be evidently revealed by the results of cluster analysis when the fauna] analogs rooted in community relationship, bipolar distribution and low efficiency of collections have been identified.
Changes in faunal affinity demonstrate that biogeographic evolution of Permian brachiopods had been profoundly influenced by the consolidation of the Pangea, which was finalized by the close of Ural seaway at the end of Artinskian Stage, and led to a sharp differentiation of a pro-Pangea faunas and the Tethyan faunas. The brachiopod faunas in peri-Pangea shelves are dominated by a group of such forms as Spiriferella, Neospirifer, the syringothyrids and the buxtoniids, which directly descended from Cisuralian faunas. These faunas are conservative as they extended upward to the Lopingian with little evolutionary changes. The faunas dwelt in off-shore islands of Tethys and Panthalassa were characterized by newly developed endemic brachiopods but lacked pro-Pangea taxa. Between these two end-member faunas there were transitional faunas occurring in the peripheral islands of Pangea.
