Wing evolution in birds (IMAGE) University of Tokyo Caption A branch of the tree of life that includes the time when the propatagium, vital to flight in future birds, came about. Credit ©2023 Yurika Uno and Tatsuya Hirasawa CC-BY Usage Restrictions Credit must be given to the creator. License CC BY 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.