Savannah Monitor Lizard (IMAGE) University of Utah Caption A monitor lizard hugs a branch. A new University of Utah study found that air flows mostly in a one-way loop through the lungs of savannah monitor lizards, just as it does in birds, alligators and presumably dinosaurs. The discovery means this unusual one-way airflow may have evolved 270 million years ago -- 100 million years before birds first flew. Credit © Cheryl A. Ertelt. Usage Restrictions Credit with copyright bug required. License Licensed 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.