UncommonDescent reviews some new CGI of dinosaurs. It’s impressive visually, but the audio is stuck in the Godzilla era. The dinos emit hoarse roars.
Birds are little dinos. So the ancient huge birds would have the same type of vocal mechanism with a VASTLY longer resonant cavity. They would sing complex songs in the same way, but the sound would be more like the 16-foot pedal register on a pipe organ, compared to the diapason flute of the modern submini birds.
I wrote a comment suggesting that the song of the meadowlark should be transposed to the pedal register….
And then I realized that it’s already been done.