Early birds quacked

by Bethany Augliere
Wednesday, January 18, 2017

Researchers have found the oldest-known avian voice box from an ancient bird that lived more than 66 million years ago. Scientists found the vocal structure, called a syrinx, while examining the fossil remains of a specimen of Vegavis iaai, a Late Cretaceous diving bird similar to modern ducks and geese. The finding suggests that the prehistoric bird may have “quacked” like modern ducks, says Julia Clarke, a paleontologist at the University of Texas at Austin and lead author of the new study in Nature.

The voice box of modern birds is unlike that of mammals and other four-legged creatures. In humans, for instance, vocal cords are suspended from a cartilaginous support structure in the windpipe in our throats. Birds' vocal organs, meanwhile, lie deep in their chest, where the windpipe branches to the lungs. “Most people don’t realize that birds sing from deep in their chest. That’s where sound is produced,” Clarke says.

Scientists from the Argentine Antarctic Institute first uncovered the fossil skeleton on Vega Island in Antarctica in 1992. “It’s the most complete fossil of a relative of living bird lineages from the Mesozoic Era,” she says. Meticulous preparation of the specimen ultimately enabled Clarke and her colleagues to find the preserved three-dimensional syrinx, which they analyzed using high resolution X-ray techniques. They then compared the syrinx of V. iaai to the vocal organs of 12 living birds and one fossilized species that lived during the Eocene.

The team found that the syrinx was asymmetric, like that of modern ducks, which would have produced two sound sources and would have likely resembled quacking. A syrinx has never been found in nonavian dinosaurs, Clarke says, so it might have evolved “after the origin of flight.”

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