Pterosaurs, often incorrectly called pterodactyls, were flying reptiles that dominated the skies of the Mesozoic Era for over 160 million years. These creatures were close relatives of dinosaurs and crocodiles, belonging to the group Archosauria. Determining the exact sound a pterosaur made is challenging because the soft tissues responsible for vocalization, such as the larynx and vocal cords, rarely preserve in the fossil record. Scientists must rely on skeletal structures and comparison with living relatives, like crocodilians and birds, to reconstruct a likely sound profile based on skull shape, throat structure, and body size.
The Scientific Hypothesis for Pterosaur Vocalization
The consensus is that pterosaurs likely produced a range of simple, non-melodious sounds, unlike the complex songs of many modern birds. These sounds would have been generated by a basic larynx structure, similar to that found in modern reptiles, without the specialized vocal organ known as the syrinx. Potential sounds hypothesized include hisses, croaks, and low-frequency rumbles, aligning with the vocal capabilities of their reptilian relatives.
The massive size of later species, such as Quetzalcoatlus, suggests their sound was heavily influenced by body mass, producing deep, resonant vocalizations. Large animals naturally have longer vocal tracts and lower fundamental frequencies, meaning their calls could have been felt as much as heard, potentially as infrasound. This low-frequency sound is comparable to the deep booms and growls produced by large modern archosaurs, such as ostriches or crocodilians. Smaller pterosaurs may have produced higher-pitched squawks or sharp shrieks, similar to some seabirds that lack a complex syrinx.
Anatomical Clues in Fossil Evidence
Scientists infer pterosaur sounds by examining the preserved bony elements that supported the throat and windpipe. Pterosaurs appear to have relied on a simpler larynx located at the top of the trachea, functioning primarily to guard the airway and produce sound through simple vibration of soft tissues, much like in non-avian reptiles.
The hyoid apparatus, a complex of bones supporting the tongue and the floor of the mouth, provides further clues about the control of the throat and vocal tract. Although delicate hyoid bones are rarely preserved, their structure would have dictated the mobility of the tongue and the shape of the oral cavity, which influences sound resonance and articulation. The overall size of the trachea, estimated from surrounding bone structure, also directly impacted the pitch and volume of any sound produced. For giant species, the sheer length of the neck and trachea would have acted as a massive resonating chamber, deepening the pitch into a powerful, low-end sound.
Communication and the Function of Cranial Crests
The elaborate cranial crests seen in many pterosaur species, such as Pteranodon and Tapejara, were used for visual communication, particularly in species recognition or sexual display. These striking features, often consisting of bone supporting a large, colorful membrane, provided clear visual signals to potential mates or rivals. Some researchers suggest these crests may have served a dual role, also playing a part in acoustic communication.
The hypothesis is that the internal structure of some crests could have acted as a sound modulator or amplifier. An analogy is often drawn to the hollow, looping nasal passages found in some hadrosaurs, where a crest turned simple vocalizations into resonant, directional calls. While pterosaur crests did not typically contain looping passages, their shape and associated soft tissue may have enhanced the simple sounds generated by the larynx. By modulating the air passing through the head, a pterosaur could have amplified a low growl or hiss into a more complex, booming call for long-distance communication or territorial defense.