ABSTRACT
Although the data of fossil isocrinids are still scarce, it is suggested that a relatively striking turnover of isocrinid fauna occurred in the western Pacific during the period between the late Early Miocene and Recent. This turnover includes the disappearance of Teliocrinus, Isocrinus and Isselicrinus from the western Pacific, and the introduction of Metacrinus and Saracrinus into this area. Separation of the Pacific and the Indian Ocean by archipelagoes and wide shelf area in southwest Asia since late Tertiary has brought a contrasty, independent isocrinid fauna in the each ocean. Isocrinids are mostly upper bathyal inhabitants, and such shallow area has been a geographic barrier. In contrast, more than 30% of Japanese comasterid comatulid species are also found in the Indian Ocean, suggesting that shallow-water fauna is less subjected to such faunal separation.
