Why joint angles matter (IMAGE) University of Tokyo Caption The way arm joints are articulated in fossils gives away the presence or absence of the propatagium. 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.