Using CT scans, she compared the ancient syrinx to that of 12 other modern birds as well as another ancient fossil, and found that the organ was most closely related to those seen in ducks and geese. The finding suggests that birds, which are living dinosaurs, evolved the organ relatively late in their evolutionary line.

The authors also concluded that it’s possible that because no nonavian dinosaur specimen has ever been found with a syrinx, those dinosaurs most likely did not make honking noises. She and her colleagues suggested in a previous study that nonavian dinosaurs may have made booming sounds like ostriches.

“We don’t see a syrinx or anything like a syrinx in the nonavian dinosaurs, and we have an amazing fossil record,” said Patrick O’Connor, a professor of anatomy at Ohio University who wrote an accompanying article in the issue of Nature. He said that although the research does not completely rule out the possibility that nonavian dinosaurs had these organs, the finding might encourage more researchers to be on the lookout for syrinxes in the fossil record. “People will think differently now when they are studying their fossils,” he said.

Joel Cracraft, the Lamont curator at the American Museum of Natural History’s department of ornithology who was not involved in the study, praised the team’s discovery of the ancient syrinx.

“Paleontologists call some of these types of fossils roadkill because they are flattened in the strata and they’ve lost some of their elements,” he said. “But they used the very best of technology to get out very incredible detail. This is the best, and practically the only, comparative analysis of syrinx in all of these early modern birds.”