Your ammonite probably is...

Prionocyclus

Prionocyclus had a fairly narrow profile and flattened flanks. The whorls barely overlapped and the umbilicus was wide. It had a wide venter with a smooth, narrow keel. It had simpler sutures and irregular strong radial ribs. It had some tubercles. Prionocyclus marks the Turonian stage of the Upper Cretaceous.