Oldest known vocal organ of birds suggests dinosaurs may not sing

Cretaceous syrinx fossil

In a study newly published in Nature, researchers from The University of Texas at Austin found the oldest known vocal organ of a bird in an Antarctic fossil of a relative of ducks and geese that lived more than 66 million years ago during the age of dinosaurs.

The discovery of the Mesozoic-era vocal organ (syrinx) and its apparent absence in non-avian dinosaur fossils of the same age indicate that the organ may have originated late in the evolution of birds and that other dinosaurs may not have been able to make noises similar to the bird calls we hear today.

The syrinx was found in a fossil of Vegavis iaai, a bird that lived during the Cretaceous. The bird was discovered on Antarctica’s Vega Island in 1992 by a team from the Argentine Antarctic Institute.

The syrinx is made of stiff, cartilage rings that support soft tissues that vibrate to produce the complex songs and calls of modern birds. Cartilage does not fossilize as well as hard tissues such as bone. But the high mineral content in the syrinx’s rings sometimes allows for fossilization.

All other known examples of fossilized syrinxes occur in birds that lived well after non-avian dinosaurs went extinct.

Researchers suggest that the finding can help explain why no such organ has been preserved in a non-bird dinosaur or crocodile relative. It is another important step to figuring out what dinosaurs sounded like as well as giving us insight into the evolution of birds.

In addition, it is the beginning of the work to determine what the fossilized organ can tell about the sounds of early birds. Researchers begin to outline how fossilizable characteristics of the syrinx may inform people about sound features, but we need a lot more data on living birds.

Finally, the evolution of vocal behavior can give insights into other anatomical features, such as the appearance of bigger brains. This study follows previous research in the group and they have major implications for dinosaur sound-making throughout time.

Other parts of the study include working with engineers to model sound-producing organs, a project funded by the Gordon and Betty Moore Foundation.

News Source: The University of Texas at Austin
Citation: Clarke JA, et al. (2012). Fossil evidence of the avian vocal organ from the Mesozoic. Nature, published online. DOI: 10.1038/nature19852.
Figure legend: This Knowridge.com image is credited to Nicole Fuller/Sayo Art for UT Austin.