Temporal changes within the latest Cretaceous and early Paleogene turtle faunas of northeastern Montana

Climate change has been suggested to be a factor in the distribution of reptiles in the Cretaceous and Paleogene, but comparatively few studies have examined the possible role of climate within lithostratigraphically or biostratigraphically constrained local areas. Here, we reexamine the role of climatic change on the distribution of turtles within the Late Cretaceous-earliest Paleogene record of the Hell Creek area of northeastern Montana, where long-term field studies have produced a relatively dense record of faunal change during a period of climatic fluctuation. An improved stratigraphic record allows us to document previously unavailable range data for the Hell Creek-Tullock turtle taxa and assess changes in richness and abundance through approximately the last 1.9 m.y. of the Cretaceous and the first 750 k.y. of the Paleocene and provide revised estimates for survivorship and extinction across the Cretaceous-Paleogene boundary.