For a long time scientists have argued that the extinction of the dinosaurs was related to climate change. A. A simple climate change does not explain some important data related to the extinction of the dinosaurs at the end of the Cretaceous. B. The retreat of the seaways at the end of the Cretaceous has not been fully explained. C. The abruptness of extinctions at the end of the Cretaceous and the high concentration of Ir found in clay deposited at that time have fueled the development of a new hypothesis. D. Extreme changes in daily and seasonal climates preceded the retreat of the seas back into the major ocean basins. E. Some scientists hypothesize that the extinction of the dinosaurs resulted from the effects of an asteroid collision with Earth. F. Boundary clay layers like the one between the Mesozoic and Cenozoic are used by scientists to determine the rate at which an extinct species declined.