Two incomplete specimens of Aldanella attleborensis were recovered from calcareous dolomite of the Walidiala Group, Taoudeni Basin, northern Guinea. This is the first record of Cambrian shelly microfossils from west Africa and the first record of Aldanella from a western Gondwanan continent. These fossils, the regional stratigraphy, and radiometric dating place the dolomite, previously considered to be Late Proterozoic in age, in the Early Cambrian. Proterozoic and lower Paleozoic strata in the Taoudeni Basin are generally unfossiliferous. Hence, A. attleborensis and associated microfossils are biostratigraphic markers of geologic importance in west Africa. The Lower Cambrian dolomite near Walidiala is separated from Precambrian tillite by a previously unrecognized disconformity within the Walidiala Group that represents a hiatus of uncertain duration.