How Dinosaurs Talk With Their Feathers

What did Tyrannosaurus sound like? The movies tell us that the dinosaur shrieked and roared, befitting its status as one of the largest carnivores of all time, but the truth is that we don’t really know. The soft tissues needed to reconstruct the dinosaur’s sounds have never been found, rendering the ancient bones mute. The same is true for almost every other species of non-avian dinosaur yet discovered. The only exceptions are the crested hadrosaurs, whose circuitous nasal passages have allowed paleontologists reconstruct their tuba-like calls.

Without preserved soft tissues, the nuances of the dinosaur vocal range remain out of earshot. But it’d be a mistake to simply lament the silence of the fossil record and move on. Dinosaurs would have been able to make noise in other ways. As paleontologist Phil Senter pointed out in a review of prehistoric animal sounds, non-avian dinosaurs may have communicated with each other by “hissing, clapping jaws together, grinding mandibles against upper jaws, rubbing scales together, or use of environmental materials (e.g. splashing against water).” Even without dinosaurian roars, the Mesozoic wouldn’t have been entirely quiet.

And there’s another possibility. Enfluffled dinosaurs may have been able to talk with their plumage.

Each year dinosaurs keep getting fuzzier and fuzzier. Feathers, protofeathers, and strange bristles are turning up on an increasing number of non-avian dinosaurs, indicating that such secondary body coverings either evolved multiple times in the dinosaur family tree or were inherited from the last common ancestor of all dinosaurs. And while such dinosaurian fluff and fuzz is often considered in the context of visual displays, it’s also relevant to sound.

Modern, avian dinosaurs may be our window into the past here. When male club-winged manakins try to impress females of their species, they make a “Tick-Tick-Ting” sound. They do this with their feathers. Thanks to some specialized feather anatomy, ornithologists Kimberly Bostwick and Richard Prum found, the male manakins are able to rub their feathers together to make sexy sounds that are just as loud as a typical bird song. And birds are hardly the only vertebrates to use structure for sound. Little mammals called streaked tenrecs can make clicking noises with specialized quills they rub against each other thanks to a unique patch of soft tissue called a “quill vibrator disc.”

Perhaps non-avian dinosaurs could have sounded with stridulating feathers and bristles, too. Maybe bird-like species such as Anchiornis or even Velociraptor could rub their exquisite feathers together to tick or buzz, and I can’t help but imagine Psittacosaurus shaking its tail to rustle its quill-like bristles.

Whether any extinct dinosaurs actually behaved this way, however, relies on first discovering intact sound-specialized structures along with the bones. Such a find seems like a long shot. But if paleontologists someday find a dinosaur fossil with acoustic feathers, they might be able to do something long thought to be impossible.

Just as paleontologists have been able to reconstruct dinosaur colors on the basis of feather microanatomy, structure may allow researchers to replay dinosaur sounds. In fact, paleontologists have already achieved such a feat with a very different animal. Working from a delicately-preserved fossil, paleontologist Jun-Jie Gu and colleagues were able to reconstruct the sound of a Jurassic katydid that had acoustic “files” on its wings which created a chirping noise when rubbed the right way. If paleontologists someday find a dinosaur with similarly musical plumage, we will be able to hear them sing again for the first time in over 66 million years.

[Thanks to Phil Torres for telling me about the club-winged manakins and inspiring this foray into speculative paleontology. Top art by the most-excellent John Conway.]

References:

Bostwick, K., Prum, R. 2005. Courting bird sings with stridulating wing feathers. Science. 309: 736

Endo, H., Koyabu, D., Kimura, J., Rakotondraparany, F., Matsui, A., Yonezawa, T., Shinohara, A., Hasegawa, M. 2010. A quill vibrating mechanism for a sounding apparatus in the streaked tenrec (Hemicentetes semispinosus). Zoological Science. 27 (5): 427-432

Gu, J., Montealegre-Zapata, F., Robert, D., Engel, M., Qiao, G., Ren, D. 2012. Wing stridulation in a Jurassic katydid (Insecta, Orthoptera) produced low-pitched musical calls to attracts females. PNAS. 109 (10): 3868-3873

Senter, P. 2008. Voices of the past: a review of Paleozoic and Mesozoic animal sounds. Historical Biology. 20 (4): 225-287