Late Mesozoic Bivalve Biogeography of Antarctica

Throughout the late Mesozoic a distinctive bivalve fauna can be traced around the southern Gondwana margins. It is characterized by inoceramids (Retroceramus, Inoceramus, Anopaea), oxytomids (Malayomaorica, Arctotis, Aucellina, Maccoyella), and buchiids (Jeletzkiella, Australo buchia?), together with certain other types such as monotids and trigoniids. Throughout much of this period the fauna appears to have been centered on a core region which stretched approximately between southern Patagonia and Indonesia. However, it expanded in the Tithonian to include the Himalayas, and at the Jurassic-Cretaceous boundary, clear transitions to more diverse faunas can be detected in both southern South America and the India-East Africa region. The presence of a distinct austral bivalve fauna suggests that there may well have been some form of climatic zonation at high latitudes in the southern hemisphere. Support for this claim comes from the phenomenon of bipolarity which is well defined in several Late Jurassic and Early Cretaceous genera. The existence of an abundant late Mesozoic bivalve fauna in Antarctica further underlines the importance of polar regions as potential evolutionary and dispersal centers.