The Otavi and Nama Groups of Namibia span the late Proterozoic and early Cambrian periods. The fossil record of these two groups documents evolution during a particularly interesting stage of the Earth's history - the period during which the transition from primitive diploblastic organisms to triploblastic, muscle-powered, metazoans with nervous systems, occurred. It was also a period of evolution of an extinct group of organisms, the Vendozoa. Much remains to be learnt about the organisms of this period, this paper being in the nature of a review of work that has already been done on the fossils of the Otavi and Nama Groups.