It stems from the fact that it was thought that birds used only a very specialized organ called the syrinx to vocalize, something which non-avian dinosaurs have no indication of, and crocodilians don't have.

However, it has since been discovered that birds do in fact use their larynx (the sound organ used by crocodilians as well as other reptiles and mammals) in order to create some of their vocal sounds. So, and sound a bird makes with this organ, along with sounds crocodilians make, non-avian dinosaurs should also be able to do in theory.

I'd personally venture that the vast majority would be low end grumbles and growls in the order of crocs and ratites though.

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WINGS ON MY BACK LEGS.

No worries! It's well deserved, keep up the awesome work.

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WINGS ON MY BACK LEGS.

Thanks!

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WINGS ON MY BACK LEGS.