Current (and lowest common) thinking is that dinosaurs were dumb, despite living and evolving for 165-180 million years in the not exactly user-friendly environs that was the Mesozoic era.
This thinking neglects to add that long, looong after those after-effects of a big meteor had wiped out the big 'uns, their tiny, obviously very intelligent, problem-solving, song-making, sentient-proven avian survivors added another ~60 millions years, which they continue to do to this day.

