The “extremely rare” discovery of an 80-million-year-old fossilized larynx that belonged to an armored dinosaur shows the ancient animal may have sounded more bird-like than experts previously thought, new research suggests.
Pinacosaurus grangeri — a squat, armored, club-tailed ankylosaur unearthed in Mongolia in 2005 — was discovered along with the first fossilized vocal tract (larynx) found in a non-avian dinosaur.
Well, a new analysis published in the journal on Feb. 15 communication biology (opens in new tab)suggests that the creature’s vocalizations may have been far more subtle and melodious than the previously assumed crocodile grunts, hisses, rumbles, and roars.
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“Our study locates the larynx of Pinacosaurus is kinetic and large, similar to birds, which make a variety of sounds,” study the first author Junki Yoshida (opens in new tab), a paleontologist at the Fukushima Museum in Japan, told Live Science. Dinosaurs are archosaurs, a group whose living members include crocodiles and birds. These animals use sounds for a variety of purposes, including courtship, parental behavior, defense against predators, and territorial calls. “So those are the candidates for its acoustic behavior,” Yoshida said.
At the beginning of the Triassic, about 250 million years ago, archosaurs split into two major groups: a bird-like group, which later developed in dinosaurbirds & pterosaursand a second group that later branched out into crocodiles, alligators, and a number of extinct relatives.
Most animals that produce sounds do so through specially adapted organs connected to the lungs through the trachea. In crocodilians, mammals, and amphibians, the larynx—a hollow tube located at the top of the trachea and stuffed with folds of resonating tissue—is primed for making sound. But in birds, the syrinx — a two-tube structure that rests near the lungs at the bottom of the trachea — creates the basis for complex melodies.
To estimate the range of sounds S. grangeri The researchers examined two parts of the fossil larynx that would have worked with muscles to lengthen the airways and change their shape, and compared them to structures in the larynxes of living birds and reptiles. That’s what they found S. grangeri had a very large cricoid cartilage (a ring-shaped piece of cartilage involved in opening and closing the airway) and two long bones used to adjust its size – a layout that rotated that S. grangeri voice box into a voice modifier.
This anatomical set-up likely meant the ancient herbivore was able to make a variety of sounds — including rumbles, grunts, roars, and possibly even chirps — while roaring them over great distances at the same time, the researchers said.
However, it is unlikely that ankylosaurs chirped or warbled like modern birds, mainly because they were much larger and had vastly different vocal mechanisms.
“It’s really hard to even begin to infer what Pinacosaurus sounded because this is probably an entirely new type of vocal organ, producing its own distinctive sound,” James Napoli (opens in new tab), a vertebrate paleontologist at the North Carolina Museum of Natural Sciences who was not involved in the study, told Live Science. “I think chirping birdsong, despite functional similarities to a syrinx, is unlikely just because ankylosaurs were so large. In my mind, I envision low, reptilian rumbles and grunts and roars with an intricate bird song-like complexity.”
The researchers said their future research will focus on narrowing the possible range of S. grangeri Vocalizations when searching for other specimens that may contain preserved larynxes or even a syrinx.
“Dinosaur sounds are one of those persistent unknowns that makes this work all the more exciting,” Napoli said. “Without fossilized vocal organs, which are extremely rare, it’s really hard to even begin to guess the limits of dinosaur vocalizations, let alone what they actually sounded like.”