Unusual forms of orbitoidal foraminifera in the Maastrichtian of Turkey

Maastrichtian orbitoidal foraminifera in Turkey show a variety of unusual f eatures. They include remarkable specimens of their reproductive life cycle , lateral chambers within the embryo, teratological individuals (polyvalenc e), microboring activity within tests, equatorial chamber growth, and conic al forms. These features provide evidence for Maastrichtian orbitoidal fora miniferal systematics, biological life cycle, palaeoecological conditions a nd fossilization. The growth of lateral and equatorial chambers is thought to have been controlled largely by genetic characteristics. Microboring act ivity is the result of their fossilization and life relationships with othe r micro-organisms such as Talpinella conicularia. Conical forms and polyval ence are thought to be related to sedimentological characteristics of the p alaeoenvironment, such as currents. Abnormal growth of the equatorial chamb ers is accepted as one of the main distinguishing features of Orbitoides gr uenbachensis. (C) 2000 Academic Press.