system
A chat on subreddit /r/NoStupidQuestions
human
We can't prove they were or were not intelligent. Our evidence of intelligence in animals that we are pretty damn sure are very intelligent (some dolphins, elephants, bonobos, corvids) is observational. We *see* them doing intelligenct things, but they leave behind precious little physical evidence.

So, it's possible some were intelligent and we just don't know and can't prove it one way or the other.

Plenty of dinosaurs lived in situations that tend to lead to intelligence in modern times (complex social structures, mostly).
gpt
One of best lines on the subject I have read - it was a couple years ago in an article criticizing the term 'anthropocene' and saying how humans grossly overestimate their influence on the world, was something like 'even if dinosaurs had highly complex civilizations and waged nuclear warfare against each other, odds of us getting evidence of that are very slim'.  Tens/hundreds of millions of years ago is a very long time, and the whole world looks different now, continental plate movements and all that...

Based on their anatomy as we know it today it's unlikely, but also so many dinosaurs have been recreated off literally a handful of bones, not entire skeletons, what we do know is mostly speculative.