LATE MIOCENE CALCAREOUS NANNOFOSSIL GENUS CATINASTER - TAXONOMY, EVOLUTION AND MAGNETOBIOCHRONOLOGY

A systematic study on the evolution and stratigraphic distribution of the species of Catinaster from several DSDP/ODP sites with magnetostra tigraphic records is presented. The evolution of Catinaster from Disco aster is established by documentation of a transitional nannofossil sp ecies, Discoaster transitus. Two new subspecies, Catinaster coalitus e xtensus and Catinaster calyculus rectus are defined which appear to be intermediates in the evolution of Catinaster coalitus coalitus to Cat inaster calyculus calyculus. The first occurrence of C. coalitus is sh own to be in the lower part of C5n.2n at 10.7-10.9 Ma in the low to mi d-latitude Atlantic and Pacific Oceans. The last occurrence of C. coal itus coalitus varies from the upper part of C5n.2n to the lower portio n of C4A. Magnetobiostratigraphic evidence suggests that the FO of C. calyculus rectus is diachronous. Catinaster mexicanus occurs in the la te Miocene and has been found only in the eastern equatorial Pacific, the Indian Ocean and the Gulf of Mexico.