Tyrannosaurus bellows (IMAGE) University of Portsmouth Caption Tyrannosaurus rex bellowing with its mouth shut, like a vocalising alligator. With its mouth closed, all of the enormous teeth of T. rex would be invisible behind its lips. Credit Mark Witton Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.