Syrinx Infographic (IMAGE) University of Texas at Austin Caption Study of the first fossil vocal organ from the Mesozoic provides insight into the evolution of bird calls and song. The fossil syrinx is from the late Cretaceous of Antarctica. Within dinosaurs there was a transition from a vocal organ present in the larynx (present in crocodiles) to one uniquely developed deep in the chest in birds. Credit Nicole Fuller/Sayo Art for UT Austin. Usage Restrictions credit 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.