Fossil dunes are widespread in the Namib Desert, especially in the Sperrgebiet and the Namib-Naukluft Park where fragments of fossil "ostrich" eggshells have been known for a long time. But it was only in the 70's and 80's that they were collected for scientific purposes (Ward and Corbett, 1990). Recent fieldwork by the Namibia Palaeontology Expedition in the same areas led to the collection of a diverse series of fossil struthious eggshells associated with mammals at several localities. We have identified more than a hundred fossiliferous sites where 8 different types of eggshells occur which differ in their pore complexes and pore density. Three genera of eggshells have been identified: Namornis, Diamantornis, and Struthio. No two eggshell types occur together in the same stratigraphic level and when several types of eggshells are found in superposition, they always occur in the same order. In older levels (Lower Miocene), aepyornithoid eggshells have also been recorded. Eggshells are thus proving to be extremely useful for biostratigraphy and for correlating strata in the Namib and elsewhere in the Old World (South Africa, Tanzania, Arabian Peninsula). Having been calibrated by associated mammal faunas, the Namib egg sequence can now be used for geochronological purposes and the Namib Desert is suggested to have originated ca. 16 Ma.