Bipolar distributions of recent and mesozoic radiolaria

Bipolar distributions of recent polycystine Radiolaria are discussed and reviewed in this study. The numerous data on biogeography obtained by using plankton tow-net, sediment trap, and surface sediment samples are discussed from available studies in global oceans. The bipolar distribution of radiolarians is grouped as two types; bipolar taxa that are found in the polar and temperate sea water but are lacking in the tropic ocean (Type 1) and those taxa found in both shallow water in polar oceans and deeper bathymetric depths under the tropics (Type 2). The distribution patterns of the representatives of the bipolar species are discussed, and concluded that Pseudodictyophimus gracilipes, Stylochlamydium venustum and Spongotrochus glacialis show type 2, while Spongurus pylomaticus shows similar to type 1, but the species dwells in intermediate and deeper waters. In addition, another examples of monopolar distribution that was developed in around the Antarctic Ocean and the Arctic Ocean are examined on the endemic taxa as the genus Antarctissa and Amphimelissa setosa. The other example of the bipolar distribution of Mesozoic Radiolaria is the genus Glomeropyle from the Triassic in New Zealand and NE Siberia. The latest knowledge on the Early Triassic radiolarian faunal changes in a pelagic environment in southern high latitude since the P/T boundary is presented. Recent progress on the oceanic Permian/Triassic boundary sequence at Arrow Rocks, New Zealand revealed a possibility that the southern high latitude ocean had been acted as a refugee area for the surviving biota including Permian-type Radiolaria since the end-Permian mass extincion events. The common characteristics in general morphology between the Recent and Mesozoic bipolar species are discussed.