I think they barked and that as their mouths were huge they might as well have produced a big growl terrifying the other dinosaurs. It would probably have sounded like an eagle, but lower in tone with a bass register, because dinosaurs may have evolved into big birds.
...Dinosaurs make no sounds, as they have been extinct for over 65 million years.
What sounds they may have made is anybody's guess and left to each individual's imagination.
They can guess but no one knows. Since dinos and birds have many common charecturistics they could have sang like canaries. (but with a much deeper voice)
...Some had nasal passages similar to birds. Yet there is no sure way to know what sound they would have made.
...Being reptile like for the most part, we can guess dinosaurs primary sounds were various hisses.
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