This is from Neil Landman curator of the American Museum Of Natural History in New York

The ammonite is part of the group known as Acanthocerataceae. More specifically, it may belong to the genus Dunveganoceras. They are mostly identified by the big spines. The are known from Wyoming and occur in the Cenomanian of the Upper Cretaceous. They probably favored shallow water in the ancient Western Interior Seaway.