A resonating chamber is an anatomical structure found in many vertebrate animals, including dinosaurs, which is used for enhancing the sounds produced in vocalization. It is an air-filled cavity typically located in the throat or head of the animal. Sound produced by the vocal organs is forced through this chamber, which modulates the intensity and timbre of the noise. This is especially important in intelligent animals with complex forms of communication, as it increases the range of noises they are capable of making. This makes language possible.
The resonating chambers of eudromaeosaurian dinosaurs, popularly called “raptors,” have played a significant role in the history of de-extinction. Research by paleontologists in the 1990s and early 2000s led to the identification of a resonating chamber in fossilized remains from Fort Peck Lake, Montana; a 3D-printed replica was subsequently created from scans of the fossil skull using a rapid prototyper. By observing de-extinct specimens of Velociraptor, it was possible to discern the meanings of their vocalizations and mimic them. This was an important first step in learning how to manage Velociraptor and its relatives in captivity.
Resonating chambers are hollow, air-filled structures in the head or throat of an animal, with apertures allowing air to flow through and carry sound waves generated by the vocal organs. In most tetrapod animals, the vocal organ is the larynx, though only mammals and a handful of lizards possess vocal folds allowing them to make complex vocalizations. Birds instead have a syrinx, though this is absent in non-avian dinosaurs, which instead have a similar organ with separate evolutionary origins.
In many animals, there are several defined resonators. The three most effective are the pharynx, oral cavity, and nasal cavity, along with the vocal organs themselves. Other parts of head and throat anatomy such as the lungs, tracheal tree, and sinus cavities have much lesser effect on resonance. Nasal resonance in particular produces a bright, edgy tone which adds clarity to the vocalization and helps with projection. In raptors such as Velociraptor, nasal resonance is the primary type of vocal resonance used. This dinosaur’s nasal resonating chamber is a thin-walled bony structure, roughly teardrop-shaped with the narrow end facing forward, with one small aperture in the front for air entry from the nose and two larger apertures in the rear for air exit into the back of the throat. Having two means of air exit allows the animal to modulate the sound it produces by opening or constraining the passages connected to the resonating chamber.
To the animals which possess such resonating chambers, they are an essential part of communication. By enhancing the sound produced, an animal can change its pitch and tone, thereby changing the intended meaning of the sound. Some animals, such as humans and Velociraptors, have highly complex means of vocal communication; resonating chambers allow for a wider range of communicative vocalizations and thus a broader language. Scientists can study the resonating chambers of animals by creating replicas of them, or by researching live animals, to better understand how various creatures communicate with one another.
The eudromaeosaurian nasal resonating chamber has further use to science, both in terms of research and (perhaps surprisingly) animal care. In 2001, fossilized remains near Fort Peck Lake, Montana (identified as “Velociraptor” antirrhopus, referred to Deinonychus by modern paleontologists) were discovered by Dr. Alan Grant and Billy Brennan with the nasal resonating chamber intact. By scanning the fossilized skull, a computerized model of the resonating chamber was created, and then printed as a 3D model by a rapid prototyper operated by Brennan. Using this model, sounds produced by the animal when it was alive could be replicated. Grant, who had previously encountered de-extinct Velociraptors cloned by International Genetic Technologies, noted that the sounds produced through the model were nearly identical to the vocalizations he had heard from the cloned raptors.
Shortly after the replica’s production, Brennan and Grant were brought to the island of Isla Sorna for an illegal rescue operation; Isla Sorna was inhabited by de-extinct animals. Brennan brought the resonating chamber replica in his camera bag, probably to demonstrate (as he and Grant were led to believe the mission was a wildlife tour). During the incident, Dr. Grant encountered Velociraptors and identified the meanings of several of their vocalizations; later in the incident he utilized the resonating chamber replica to mimic their calls. This confused the raptors, and when helicopters passed nearby coincidentally after Grant mimicked the raptors’ cry for help, the raptors ceased their attack and retreated. This was the first reported example of a human successfully communicating to a Velociraptor.
While research into Velociraptor communication has advanced greatly since 2001, the use of resonating chamber replicas in this capacity is limited. However, in the 2015 Jurassic World Video Game, a nasal resonating chamber is a usable item that can summon Velociraptors and is the key to winning the game; since the 2001 incident’s public record was heavily censored by the United States government, it is unlikely an average person would recognize the item. Instead, it is a reward for the player being familiar with Dr. Grant and Billy Brennan’s actual research.
From animal remains
It has been suggested that an intact resonating chamber could be recovered from a deceased animal’s body, for example the bony nasal chamber of Velociraptor being found among its skull bones. However, the quality of such an item cannot be guaranteed; it is fragile and may have been damaged during or after the animal’s death. Furthermore, in most animals, the resonating chambers include both hard and soft tissues, the latter of which decay quickly. If a resonating chamber is found among the parts of a dead animal, it is highly likely it will be damaged, non-functional, or incomplete.
A far more reliable way to obtain a resonating chamber from an animal is to replicate it using 3D-printing technology, such as the rapid prototyper used to develop the first eudromaeosaurian nasal resonating chamber replica. This ensures that the item is wholly intact. While 3D printers were hard to come by in 2001 when this replica was created by paleontology student Billy Brennan, they are much more accessible in the modern day. Using resin, plastic, or other materials, the model can be turned into a physical item layer by layer; to obtain the digital file, the anatomical structure must be scanned first.
At the moment there are no resonating chamber replicas in mass production, since demand for them is fairly low. The only known example of this item was initially produced by Dr. Alan Grant’s student Billy Brennan. It is likely that they made more for research purposes, but there are assumed to be relatively few in existence; Grant and/or Brennan probably possess the original.
Behind the Scenes
In real life, there is no evidence for a bony nasal resonating chamber in Velociraptor, Deinonychus, or other theropods; this structure is fictional. Non-avian dinosaurs lacked a syrinx, the organ that birds use to produce vocalizations, and did not have an advanced larynx like that of a mammal. Because of this, non-avian dinosaurs could only make a limited range of noises by exhaling forcefully. This would allow them to growl and roar similarly to alligators and crocodiles, and some paleontologists believe they could have vocalized similarly to waterfowl as well. Media such as the Jurassic Park films give dinosaurs a much wider range of vocalizations than they probably had in real life, with this franchise being the only major example where fictitious anatomical apparatuses are invented to justify the dinosaurs’ noises.
Famously, hadrosaurs did actually have resonating chambers that they used to enhance their vocalizations. A good example of this is Parasaurolophus, whose elaborate crest has been recreated by scientists and used to replicate the noises it may have made when alive.