Xenicibis (image) Yale University Caption The prehistoric Xenicibis used its wings like two clubs hinged at the wrist joint in order to swing at and attack one another. Credit Nicholas Longrich/Yale University Usage Restrictions With credit. 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.