 The Characiformes likely first diversified during the Cretaceous period, though fossils are poorly known.During the Cretaceous period, the rift between South America and Africa would be forming; this may explain the contrast in diversity between the two continents.Their low diversity in Africa may explain why some primitive fish families and the Cypriniformes coexist with them while they are absent in South America, where these fish may have been driven extinct.