Early Birds (IMAGE) The University of Hong Kong Caption The origins of powered flight potential in theropod dinosaurs. A selection of early birds and their closest relatives representing flightless forms and those that neared and passed the thresholds of powered flight potential. Credit Julius T Csotonyi / Michael Pittman. Usage Restrictions None 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.