Quantitative paleobiogeography is a powerful tool for detecting the migration routes of microfossils. This is factual and applicable when we select appropriate analyses for proper problems in the following manner. The quantitative study of 43 selected ostracod species (total of 136 species) from 11 countries of North Africa and the Middle East led to the detection of two migration routes in the late Early to early Late Cretaceous times. The first route of migration was from east to west during the intervals of Aptian-Albian to Cenomanian. While in the Turonian time, reduced oxygen conditions prevailed and minimized the east-west migration. The second route was from north to south for the duration of Aptian-Albian to Cenomanian. On the other hand, four ostracod biofacies, each with its distinctive environmental conditions, have been identified in the studied countries ranging in age from Aptian to Turonian.