For the first time, researchers have discovered the bird-like vocal organ of a fossil dinosaur related to modern-day ducks and geese, and the discovery suggests that its nonavian cousins lacked the ability to produce noises similar to the bird calls we hear today.
Formally known as a syrinx, the voice box in question was discovered in an Antarctic fossil belonging to a Vegavis iaai specimen that lived in the Cretaceos era roughly 66 million years ago. This bird-like creature was discovered on Antarctica’s Vega Island in 1992 and identified more than a decade later, but its vocal organ was not discovered until 2013.
“This finding helps explain why no such organ has been preserved in a non-bird dinosaur or crocodile relative,” Julia Clarke, a paleontologist at the University of Texas at Austin Jackson School of Geosciences and the person who made the discovery, said in a statement.
She added that the find was “another important step to figuring out what dinosaurs sounded like as well as giving us insight into the evolution of birds.” Clarke and her colleagues reported their breakthrough in this week’s edition of the international, peer-reviewed journal Nature.
Analysis of the organ could provide new insight into vocalizations
The discovery of the syrinx, coupled with its absence of nonavian dinosaurs which lived during the same era, suggests that it might have originally developed late in the evolution of birds, and that other dinosaurs may have been unable to produce bird-like calls, the researchers noted.
Made from stiff, cartilage rings, the syrinx supports the soft tissues that vibrate to produce each of the sounds used to create complex modern bird calls and songs. While cartilage typically does not fossilize as well as bone or other hard tissues, its high mineral content sometimes allows it to be preserved, which was the case in this particular set of Vegavis iaai remains.
Credit: J. Clarke/UT Austin.
Clarke, who was the first scientist to describe the species 11 years ago, first discovered this so-called “squawk box” in 2013 and spent much of the next two years combing the dinosaur record for evidence of other, similar discoveries. To date, none have been found. They also scanned the syrinxes of a dozen living birds, as well as the next-oldest fossilized syrnix, to compare with the Vegavis iaai organ, hoping to learn more about what early bird calls sounded like.
“Here, we begin to outline how fossilizable characteristics of the syrinx may inform us about sound features, but we need a lot more data on living birds,” study co-author Franz Goller, a physiologist from the University of Utah, explained. “Remarkably, prior to this work, there is almost no discussion of these important questions.”
Combined with previous research led by Clarke, which found that some dinosaurs likely made closed-mouth vocalizations that did not require a syrinx, the research provides new insights into the evolution of sound production throughout the lifespan of the dinosaurs. The development of vocal organs could also provide new insight into the development of features, including larger brains, she added.
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Image credit: Nicole Fuller/Sayo Art for UT Austin.
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