Middle Eocene ostracodes of the Qattamiya area, northwest Eastern Desert, Egypt : Systematics, biostratigraphy and paleobiogeography

Abstract
The Middle Eocene Observatory and Qurn Formations that are exposed in the Qattamiya area, northwestern part of the Eastern Desert
are carefully studied for their ostracod content. The detailed investigation of the ostracod content has led to the recognition of 51 species
and subspecies belonging to 31 genera and 12 families. Their vertical distribution in the three studied sections enables the detection of
three local assemblage zones. The paleoecology of each assemblage zone is also discussed. Both the Observatory and Qurn Formations
were deposited in shallow reefal carbonate platform of less than 100 m depth. Some intervals were deposited in lagoonal tropical and
hypersaline conditions with occasionally relatively deeper oscillation within the back reef area. The paleobiogeographic distribution of
the recorded ostracodes reveals that there was a direct connection between the Southern Tethyan Real and the Western Europe Tethyan
Real through which the migration of the ostracodes had occurred.