There's not shortage of examples of small animals and fish in the fossil records, not to mention plants. What evidence do you have that this is what happened?
Whatever changes occurred would have to be lethal to a wide variety of birds, land and aquatic animals, and plants, except for people and the modern animals we see today. Whatever conditions existed before that had to be suitable to all of them.
“There’s not shortage of examples of small animals and fish in the fossil records, not to mention plants. What evidence do you have that this is what happened?”
I said “for example”, to illustrate one type of drastic climate change that seems to have happened in the past that could account for the type of extinctions which occurred. I didn’t mean to imply that one cause resulted in all the extinctions, I just offered one example that I think is probably specifically relevant to dinosaurs.
“Whatever changes occurred would have to be lethal to a wide variety of birds, land and aquatic animals, and plants, except for people and the modern animals we see today. Whatever conditions existed before that had to be suitable to all of them.”
Well, ecology is precarious. A single extinction caused by environmental factors could lead to a chain of extinctions involving species which were not directly affected by the environmental factor, but which were dependent on the existence of an anchor species. One species could be affected by such a chain of events, but a closely related species living nearby with slightly different habits might escape unscathed. Trying to either predict, or speculatively reconstruct these events, with our current level of knowledge, is not going to be very fruitful I think.