main idea A. Cosmic rays from a nearby supernova explosion may have penetrated Earth's atmosphere, causing genetic changes that dinosaur populations could not survive. B. Climate changes in the tropics may have set off a chain of indirect effects that negatively affected the ecosystems in which dinosaurs lived. C. The spread of lava over large parts of previously favored habitats such as the Deccan Plateau may have made these favored areas uninhabitable for many years. D. Although the volcanic winter resulting from the formation of sulfate aerosols eventually ended, temperatures may have remained below levels required by dinosaurs to survive. E. Temperature changes and geographic shifts in climate zones due to the atmospheric effects of volcanic activity may have been significant enough to cause extinction. F. To be convincing, theories about what caused dinosaurs to become extinct must be able to explain the disappearance of other predators in the food chain at the same time