Of course there were dinosaurs. The narrative pressures were too great - too many minds wanting - too many souls hoping - the portals opened, and the psycho-osmotic pressure thrust the dinosaurs through. The Universe had become porous, like a mountain of broken rocks through which the liquid stuff of reality itself could pour.
After that, it didn’t take long for things to go back to normal. The only difference is that now - every once in a while - people remember how thin their little reality really is. They remember how close lays those other worlds, and how fragile our own is. And then - maybe - they are nicer. Just a little.
It probably won’t last long.
But we shall see.