system
Given the following post, respond as if you're commenting on Reddit:
human
How do we know that dinosaurs didn't roar, like in Jurassic Park? Would they have chirped and cawed and sang, like birds today?
gpt
Phylogenetic bracketing. None of their relatives have anything similar to vocal cords so dinosaurs most probably didn’t either, so they couldn’t exactly roar. Something like the deep hisses of crocodiles or the cassowary’s rumble might perhaps give you an idea of what they could have sounded like.

Edit: And similarly for singing, that’s not an ability all birds have but is limited to songbirds, so it’s not something we can hypothesize for dinosaurs as a whole.