The carbonate sequences of the Jandaíra Formation, Upper Cretaceous from the Potiguar Basin, contain a rich variety of fossiliferous assemblage from shallow-marine platform. The ammonites are scarce, which is explained by the nature of the depositional environment (tidal-flat to shallow platform) of the exposed carbonates at the onshore portion of the basin. A preliminary ammonite biostratigraphic zoning is proposed for this unit, based on the occurrences and systematic discussion of the group, defining assemblages distributed from the Turonian to the Campanian/Maastrichtian, inferring some paleobiogeographic affinities with others Northeastern Brazilian basins.