During the 2008 field survey of the Namibia Palaeontology Expedition (NPE) attention was focussed on the post-Cretaceous carbonate rocks of the Sperrgebiet in order to determine their ages more precisely. Four new fossil localities were discovered, three of which yielded vertebrates including mammals, as well as plants and abundant freshwater molluscs and land snails. These discoveries are of fundamental importance for improving our understanding of the timing of geological events in the Sperrgebiet. Preliminary identification of the mammal fossils indicates a Middle Eocene (Middle Lutetian) age for the Black Crow Carbonate. The Silica North and Silica South deposits are likely to be slightly older (Early Lutetian) than the Black Crow Carbonate.