AMMONITES FROM THE SARATOGA CHALK (UPPER CRETACEOUS), ARKANSAS

The Saratoga Chalk of Arkansas yields a rich ammonite fauna of 17 spec ies, referred to the Nostoceras (N.) hyatti zone. Recognition that the northwest European N. (N.) pozaryskii Blaszkiewicz, 1980, is a synony m of N. (N.) hyatti Stephenson, 1941, and N. (N.) helicinum (Shumard, 186 1) dates the zone as latest Campanian on the basis of co-occurrenc e with Belemnitella langei Jeletzky, 1948, in Poland. Most previous es timates of the Campanian-Maastrichtian boundary in the Gulf Coast have been drawn at too low a level, at least in terms of ammonite faunas. Elements of the N. (N.) hyatti zone fauna occur in the United States W estern Interior, and show the base of the Maastrichtian there to the a bove the Baculites jenseni zone.