Evolutionary biologists discuss several theories, but the problem is a psychological one. As evolutionary biologists deny progress, they cannot draw a simple conclusion: As a rule, the dominance of the retarded dinosaurs had been undermined by more advanced mammals and birds. If this rule is accepted, it doesn’t matter any more too much which event actually caused extinction. There were probably several processes that contributed: shortage of food, diseases, and defeat in competition, for instance. Maybe catastrophic events accelerated these processes, but they didn’t cause them alone. That’s for sure.
Given the plasticity of all life forms, dinosaurs could have adapted to environmental changes even if catastrophic, but what they couldn’t adapt to were the already more adapted mammal competitors. As for instance, mammals and birds were able to maintain body temperature, they were capable to stay active at night, when dinosaurs became lazy and slow according to falling body temperature. In these situations dinosaurs became easy prey to mammals and birds.
If accepted, progress is able to explain a multitude of phenomena: In transportation, why we use diesel and electricity instead of steam engines, in technology, why we use to replace old and slow computers, in sociology, why slavery had to be replaced by feudalism and later on by capitalism, and in biology, why ferns had been replaced by angiosperms. As they instinctively block out any idea of progress, evolutionary biologists seek rescue in less scientific rather religious, biotheistic, explanations, in which catastrophic events play the role of a Deus ex Machina, a natural creator.