ABSTRACT Following their origin in the Paleocene, morozovellids underwent a renewed radiation in the early Eocene and split into two main groups: a low anguloconical group represented by the M. aequa-subbotina-gracilis-formosa morphotypes and a high angloconical group represented by the lensiformis-aragonensis-causcasica morphotypes. The morozovellids became extinct in the early middle Eocene with the LAD of M. aragonensis, which marks the top of Zone E9. In this chapter we discuss the taxonomy, biostratigraphy and phylogenetic relations of eight species of Morozovella which are restricted to the Eocene: M. allisonensis, M. aragonensis, M. caucasica, M. crater, M. edgari, M. formosa, M. gracilis, and M. marginodentata. Eight other species ( M. acuta, M. aequa, M. apanthesma, M. lensiformis, M. occlusa, M. pasionensis, M. subbotinae, and M. velascoensis ) range into basal Eocene strata and were treated in the Atlas of Paleocene Planktonic Foraminifera (Olsson and others, 1999). Several middle Eocene taxa heretofore placed in Morozovella ( bandyi, crassata, coronata, lehneri ) are here excluded and assigned to the homeomorphic genus Morozovelloides (Pearson and Berggren; see Chapter 10, this volume).