摘要:Heteromorph ammonites are common in the middle Campanian Baculites scotti Zone of the United States Western Interior; the following species are described: Didymoceras binodosum (KENNEDY & COBBAN, 1993a), D. wrighti sp. nov., D. jorgenseni sp. nov., Anaklinoceras incertum sp. nov., Lewyites sulcatus sp. nov., Solenoceras mortoni (MEEK & HAYDEN, 1857), and Spiroxybeloceras kimbroense KENNEDY & COBBAN, 1999. They provide the basis for the subdivision of the scotti Zone into a lower Didymoceras binodosum Subzone, and an upper Didymoceras jorgenseni Subzone.
关键词:Cretaceous;Campanian;U.S. Western Interior;Ammonites;Biostratigraphy