Roar like a dinosaur... or maybe not.

For decades, films about dinosaurs made us believe that these ancient reptiles can open their mouths as wide as any predator can and release an earth-shaking sound as terrifying as any predator can make. However, a new study revealed many dinosaurs might have communicated similar to birds.

According to the International Business Times, modern-day birds and ancient dinosaurs are close relatives, which is why similarities that exist between the two are not at all impossible.

Researchers from the University of Texas further proved this when they did a comprehensive review of the vocal organs of birds and the kinds of sounds they make. Then they compared it with the vocal organs of dinosaurs.

Results of the analysis showed that many dinosaurs might have used closed-mouth vocalization which, as described by the news release, are "sounds that are emitted through the skin in the neck area while the beak is kept closed."

In birds, the closed-mouth vocalization is produced through a pouch on their esophagus rather than by exhaling through their open beak.

Modern birds have different ways of vocalization. For example, they use closed-mouth vocalization to attract mates or defend territory.

"Our results show that closed-mouth vocalization has evolved at least 16 times in archosaurs, a group that includes birds, dinosaurs and crocodiles. Interestingly, only animals with a relatively large body size (about the size of a dove or larger) use closed-mouth vocalization behavior," said Chad Eliason, a postdoctoral researcher at The University of Texas Jackson School of Geosciences and the study's co-author, in a statement.

Closed-mouth vocalizations in birds and crocodiles today suggest that it existed too in diverse archosaur species, such as the dinosaurs. And since birds use closed-mouth vocalizations during mating displays, perhaps dinosaurs used this, too.

The study emphasized that it has only provided clues, but until there is fossil evidence to prove it, there is no proof how "exactly" dinosaurs sounded.

The paper titled, "Coos, booms, and hoots: The evolution of closed-mouth vocal behavior in birds," is set to be published in journal Evolution.