title: Sudden extinction of the dinosaurs: latest Cretaceous, upper Great Plains, USA.
abstract: Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation of Montana and North Dakota show no evidence (probability P < 0.05) of a gradual decline of dinosaurs at the end of the Cretaceous. Stratigraphic reliability was maintained through a tripartite division of the Hell Creek, and preservational biases were corrected for by comparison of results only from similar fades as well as through the use of large-scale, statistically rigorous survey and collection procedures. The findings are in agreement with an abrupt extinction event such as one caused by an asteroid impact.
authors.affiliation: Department of Geology, Milwaukee Public Museum, WI 53233, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Sheehan
authors.forename: D E
authors.initials: DE
authors.lastname: Fastovsky
authors.forename: R G
authors.initials: RG
authors.lastname: Hoffmann
authors.forename: C B
authors.initials: CB
authors.lastname: Berghaus
authors.forename: D L
authors.initials: DL
authors.lastname: Gabriel
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D019015:Geologic Sediments / Q000032:analysis*; D018543:Minor Planets; D009009:Montana; D009658:North Dakota; D010163:Paleontology