What fossil clues help paleontologists figure out the sounds dinosaurs might have made?

Paleontologists piece together dinosaur sounds from a handful of rare fossil clues — mostly from the skull and neck. The main types of evidence are hollow bony crests with internal air passages, a fossilized voice box, ear bones and inner ear chambers, and a fossil syrinx (the bird vocal organ). In a few cases, the absence of a structure is also a clue. Here’s what each type of fossil tells us.

Hollow Skull Crests That Act Like Wind Instruments

Several duck‑billed dinosaurs (lambeosaurine hadrosaurs such as Parasaurolophus, Corythosaurus and Lambeosaurus) had enormous hollow crests on their heads. Inside these crests, the nasal passages twist into long, looping tubes and chambers — in Parasaurolophus the path was roughly 2.9 m (9.5 ft) long [1][12]. The bony walls preserve the shape, and CT scans let scientists map every curve without breaking the fossil [2][13][34].

Acoustic analysis and digital simulations show that air blown through these passages would resonate much like blowing across a jug. The crest would have amplified sound, and different crest shapes would create different vocal signatures [10][11][37][38][47]. Computer models suggest low, eerie bellows or calls that might sound like a trombone, bagpipe chanter, or medieval krumhorn [11][42]. One team even built a 3D‑printed model of a Parasaurolophus crest and found it boosted low frequencies between 581 Hz and 1,056 Hz [50][51]. The fossil skull geometry alone — sometimes studied by making actual musical instruments from casts — gives a strong sense of what kind of honks and rumbles these animals might have produced [7][14][40][43][44][49].

A Rare Fossilized Voice Box (Larynx)

Until recently, only one fossil voice box (larynx) had been found in a non‑avian dinosaur — Pinacosaurus grangeri, a squat, armored ankylosaur that lived about 80 million years ago [3][16][21][27]. The larynx is built from delicate cartilage that almost never fossilizes, making this an exceptionally rare clue. Its anatomy is bird‑like: it has a large cricoid ring (the main supporting cartilage), firm cricoid‑arytenoid joints, and long arytenoid cartilages [22][23][28]. In birds, such a setup allows the glottis to snap open for quick, loud calls and fine sound modulation [23][25].

Because of those features, paleontologists think Pinacosaurus could have made loud, explosive calls and modified its voice in complex ways — possibly including rumbles, grunts, roars, and even bird‑like chirps [3][16][24][29][30][33]. Two known larynx fossils, separated by 90 million years, hint that this kind of vocal hardware might have been widespread among dinosaurs [31][32].

Middle Ear and Inner Ear Bones

When an animal makes a sound, its ears are usually tuned to hear the same kind of sounds. Fossil ear bones therefore offer clues to what dinosaurs might have listened to — and produced.

• Stapes (middle ear bone): In Tyrannosaurus rex, this bone was nearly the size of a matchstick, indicating the ear was most sensitive to low‑frequency sounds [4][17].
• Elongated cochlea: A horse‑sized tyrannosaur called Timurlengia had an unusually long cochlear duct in its inner ear, which suggests it could hear a wide range of frequencies — perhaps to pick up high‑pitched location calls from its young [5][18][19].
• Delicate columella and inner ear in hadrosaurs: A tiny sound‑conducting bone and CT scans of the inner ear in Corythosaurus show that these duck‑bills had the right equipment to hear the low‑frequency calls their crests would have made [36][41]. Skull casts also reveal large brain regions for processing sound [45].

So the ear fossils back up the idea that many dinosaurs lived in a sonic world of deep rumbles and, for some, higher chirps from hatchlings.

A Fossil Syrinx in Early Birds — and Its Absence Elsewhere

Modern birds use a syrinx (a voice box deep in the chest) to sing and honk. A fossilized syrinx was found in Vegavis iaai, a bird that lived alongside the last dinosaurs [6][15]. The shape indicates it probably honked like a goose [9].

The key clue for other dinosaurs is what’s missing: no non‑avian dinosaur fossil has ever been found with a syrinx, and the bones that would support one are absent [8][20]. This suggests that most non‑avian dinosaurs did not make complex, bird‑like songs — if they vocalized at all, they likely used structures like the larynx or crests instead.

What’s Not in the Record

Sometimes a missing structure is just as informative. For example, there is no fossil evidence for a bony nasal resonating chamber in theropods like Velociraptor or Deinonychus — the dramatic crest‑based sound system seen in hadrosaurs was not part of their anatomy [48]. This tells paleontologists that those predators probably did not produce sounds by blowing air through a bony chamber.

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All of these fossil clues — the hollow crests with winding airways, the single petrified larynx, the tiny ear bones and cochlea, the early bird syrinx — are like physical puzzle pieces. When combined with modern imaging and computer modeling, they help scientists reconstruct the lost voices of the dinosaur world.