Hoot Goes the T. Rex?

The Tyrannosaurus, king of the tyrant lizards, wouldn’t be the same without its ear-splitting roar. But according to a new study in Evolution on dinosaur vocal abilities, the likes of the mighty T. rex probably didn’t utter the fearsome, full-throated howls that we previously imagined. Instead, they probably depended on tight-lipped booms and coos to communicate.

The sounds of the Mesozoic dinosaurs are largely a mystery; they went silent around 66 million years ago. Until now, the only species from that era that have been “heard” are duck-billed dinosaurs like Parasaurolophus. These creatures possessed hollow crests with expanded, circuitous nasal passages—the prehistoric equivalent of a tuba—that were useful for creating low-frequency sounds. But after studying the stunning repertoire of modern avians, Midwestern University biologist Tobias Riede and his team were able to uncover even more sonic possibilities among dinosaurs.

Though today’s feathered dinosaurs are known for their complex songs, they can also emit a variety of hoots, coos, and booms through shut beaks. These noises are especially prevalent in birds that are about the size of a dove or larger.

If closed-mouth sounds are tied to body size, then it’s possible that non-avian dinosaurs were able to make similar vocalizations. The lung pressure needed to inflate sacs or airways to make such sounds may only be possible for larger animals, the researchers suggest. So while there’s no direct proof of what most dinosaurs sounded like, the new study used birds to extrapolate some possibilities. Think of a Stegosaurus softly grunting as it shuffles along, or a Ceratosaurus gently cooing to impress its mate. It’s certainly a departure from the hollering hell beasts of the Jurassic Park franchise.

Of course, dinosaurs probably had an even wider soundtrack. In a 2008 paper, paleontologist Phil Senter pointed out that they could have communicated by “hissing, clapping jaws together, grinding mandibles against upper jaws, rubbing scales together, or use of environmental materials” such as water, like modern reptiles do. Birds, too, can make a ruckus by stamping, snapping their wings, and even stridulating specialized feathers together. Extinct dinosaurs could have easily done the same, in combination with their low-frequency calls. It goes to show that dinosaurs were probably more creative (and musical) than we’ve ever given them credit for.