In northeastern China, researchers have found the fossil of a small dinosaur preserved in 163-million-year-old sandstone. At just 28 inches long, Pulaosaurus qinglong wasn’t much of a fighter—but a singer. The fossil includes unusually well-preserved vocal bones that hint at an ancient origin for birdlike sounds.
Published this month in PeerJ, the new study describes Pulaosaurus as a small, fast-moving herbivore from the Jurassic period. But what sets this dinosaur apart is the surprisingly birdlike anatomy of its larynx. This is only the second known case of a non-avian dinosaur with ossified throat structures preserved, and it’s the oldest yet.
Did Dinosaurs Sing Before Birds?
Pulaosaurus lived in the thick forests of what is now northeastern China, part of a fossil-rich region called the Yanliao Biota. This region has yielded some of the most detailed dinosaur fossils ever discovered, including the feathered proto-bird Anchiornis and the bat-winged Yi qi.
But ornithischians (one of the two major groups of dinosaurs, which have bird-like hips) have been conspicuously rare in this area. The new fossil not only fills that gap but adds an unexpected vocal twist.
To analyze what the dinosaur would have sounded like, researchers used micro-CT scans with 10-micron resolution to peer inside the fossil’s bones. What they found were thin, delicate structures unlike any seen before in early dinosaurs.
In vertebrates, the larynx is a flexible structure made mostly of cartilage. It helps control the flow of air and produces sound. Most reptiles today can hiss, grunt, or groan, but they can’t produce complex vocalizations like birds do. Birds use a different organ entirely (the syrinx) which is built from delicate bones and sits at the base of the windpipe. That structure has never been found in a dinosaur fossil.
Still, Pulaosaurus’s larynx hints at something more advanced than a simple hiss. Its arytenoid bones are thin, leaf-like, and elongate—similar to modern birds. These bones serve as attachment points for muscles that help modulate airflow and pitch.
Remarkably, a similar vocal structure was discovered last year in Pinacosaurus, a heavily armored ankylosaur that lived tens of millions of years after Pulaosaurus. Both species had bony larynges with features suggesting they could make modulated sounds—perhaps not songs as we know them, but chirps, squeaks, or rhythmic calls.
What makes this discovery more intriguing is that neither species is part of the evolutionary branch that gave rise to birds. That suggests the ability to produce birdlike sounds may have evolved independently in different dinosaur lineages—or, more provocatively, that it originated in a common ancestor far earlier than scientists realized.
The Legend of the “Loud Dragon”
The name Pulaosaurus is derived from “Pulao,” a creature from Chinese mythology said to roar loudly, often carved into bells to symbolize powerful sound. The species name, qinglong, refers to the town in Hebei Province where the fossil was found.
The fossil itself, designated IVPP V30936, is almost entirely intact — a rare find in dinosaur paleontology. Preserved alongside the bones were cololites, or gut contents, as well as ceratobranchials and the paired arytenoid bones of the larynx. That anatomical detail allowed scientists to reconstruct aspects of how Pulaosaurus may have breathed and vocalized.
What exactly it sounded like, however, is not clear. But this study challenges one of the most persistent myths in paleontology: that dinosaurs were lumbering, silent beasts. Since the 1930s, Hollywood has given them thunderous roars. But the fossil record has offered little evidence for how they actually sounded.
“Even when you have a dinosaur skeleton preserved, you don’t always have these isolated bones preserved with other skull elements,” Xing Xu, a paleontologist at the Chinese Academy of Sciences in Beijing and co-author of the paper, told The New York Times. “They’re very thin bones, very delicate and hard to preserve.”
What It Means for Birdsong
Modern birds produce sound through the syrinx, a structure unique to their lineage. The syrinx has never been found in a dinosaur fossil, not even in feathered species closely related to birds. Scientists believe it may have evolved after the split between birds and other dinosaurs.
But Pulaosaurus complicates that timeline.
The dinosaur belonged to Neornithischia, a group that later gave rise to the “duck-billed” hadrosaurs and horned dinosaurs like Triceratops. Even the name of the group translates to “bird-hip,” yet these animals are not closely related to birds at all. However, the vocal structures in Pulaosaurus—and in Pinacosaurus—are unexpectedly birdlike.
According to the study’s phylogenetic analysis, Pulaosaurus is one of the earliest-diverging neornithischians ever found. That places it pretty far from the theropod lineage that led to birds.
So we’re left with two options. Either these traits evolved independently in distant groups, or they go back to an early common ancestor. That ancestor may have lived more than 230 million years ago, long before feathers, beaks, or flight.
This specimen helps us better understand the evolutionary history of dinosaur vocal anatomy, but also opens up new questions. If other early dinosaurs had similar laryngeal structures, have paleontologists simply overlooked them? Could the syrinx have evolved earlier than we thought—and simply gone unrecognized in the fossil record?
“We hope that in the future we can find more specialized structures relating to sound,” Xu said, “so we can do research on how dinosaurs produced their voices.”
For now, Pulaosaurus may be silent. But in the hands of paleontologists, its bones speak volumes.
