Iraqi National Journal of Earth Sciences

Abstract

The Ostracode biostratigraphic evidence and the evolutionary trend of Upper Cretaccous-Lower Tertiary Ostracodes are determinated by using the vertical and lateral distribution and the morphological change of the selective genera and species.
Anommatocythere; Brachycythere; Buntonia; Kaesleria; Mehsella; Nucleolina and Protobuntonia.
The evidence determinated by the study of the above taxa of this time showes closely resemblance in their morphalogical features and suddenly disappears during the Upper Cretaceous of the genera:
Brachycythere; Kaesleria; Mehsella; Protobuntonia and other species continue in the Lower Tertiary, Buntonia; Mehsella and Nucleolina. Otherwise species of Anommatocythere show first appear during the Lower Tertiary .