Antarctic Fossil Suggests Ancient Birds Honked Not Sang
Recent analysis of two fossils provides the first evidence of ancient noisemakers
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There’s a reason why people can’t sing like birds and why birds can’t hit the low notes like Barry White. People and most land animals vocalize using a voice box, or larnyx, which makes sound when air vibrates against a set of vocal cords. Our feathered friends, on the other hand, have an organ called a syrinx, which lacks vocal cords. Rather, as air passes over the specialized membranes and cartilage of the syrinx it produces sound, which can be modulated by tiny muscles.
So the big question is: if birds descended from dinosaurs, did dinosaurs tweet with a syrinx, or roar with a larynx? Because both organs are made primarily of squishy and easily degraded cartilage, they don’t fossilize well. But a new paper published in the journal Nature documents the remarkable discovery of a fossilized syrinx, helping scientists inch closer to figuring out the the ancient soundscape.
In 1992, researchers from the Argentine Antarctic Institute collected a well-preserved fossil of Vegavis iaai on Vega Island. This duck-like species lived during the Cretaceous period, 66 to 68 million years ago. They sent the specimen to Julia Clarke, a vertebrate paleontologist at the University of Texas at Austin, who described it in 2005. But it wasn't until 2013, when Clarke realized the fossil might include a syrinx, Eva Botkin-Kowacki reports for The Christian Science Monitor.
Scanning the Vegavis specimen revealed a complete, highly developed fossilized syrinx—evidence that these delicate organs can indeed fossilize, reports Botkin-Kowacki. She searched for two more years for evidence of syrinx in the fossil record, but came up empty handed. Clark and her team did, however, identify one 50-million-year-old bird fossil that contained a syrinx that was previously undocumented. But because of the lack of evidence in other non-avian dinosaurs, the researchers suspect this means that they didn't make noise using a syrinx.
“This finding helps explain why no such organ has been preserved in a non-bird dinosaur or crocodile relative,” Clarke says in the press release. “This is another important step [toward] figuring out what dinosaurs sounded like as well as giving us insight into the evolution of birds.”
Vegavis was likely a small, sleek bird that was capable of flight and also swimming, reports Rachel Feltman at The Washington Post. The shape of its syrinx suggests that the species made a duck-like honk. It is also a relatively sophisticated organ, meaning the syrinx likely underwent millions of years of development before it reached the form seen in the Vegavis specimen, but still well after the ancestors of birds split from true dinosaurs.
“It tells us that these early birds living alongside the dinosaurs may have sounded like some of the birds around today,” Stephen Brusatte, a paleontologist at Edinburgh University tells Nicola Davis at The Guardian. “If [we] were standing back in the late Cretaceous, during that calm before the asteroid hit and wiped out the dinosaurs, the air may have been filled with the songs, chirps, and honks of birds!”