Tiktaalik Reconstruction (IMAGE) University of Chicago Medical Center Caption Tiktaalik roseae, a 375-million-year-old 'fishapod' has features of both fish and four-legged tetrapods. In a new study, Tom Stewart and Neil Shubin analyzed the structure of Tiktaalik's fins just before the transition to land. Credit Flick Ford Usage Restrictions With paper 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.