The Baculites compressus zone of the Pierre Shale in Grand County, Colo., contains the following assemblage of heteromorph ammonites: Axonoceras compressum Stephenson, Anaklinoceras reflexum Stephenson, A. gordiale n.sp., Solenoceras reesidei Stephenson, Baculites compressus Say, B. undatus Stephenson, Jeletzkytes nodosus (Owen) and Hoploscaphites cf. H. landesi Ricardi. Comparisons are made with faunal assemblages from other parts of the USA and Poland. The presence of J. nodosus confirms a late Campanian age for the B. compressus zone in Colorado. -from Authors
