Bringing a movie monster to life on the big screen is more complicated than throwing in some CGI. There’s also the matter of sound. While the dinosaurs in 1993's Jurassic Park did exist at one point, we don’t know anything about the noises they made. King Kong isn’t like any gorilla on Earth, so how should he sound when he roars? The Verge explores this conundrum in the video below.

When it comes to dinosaurs, paleontologists look to their cousins—birds and crocodiles—for vocal clues. Perhaps dinos might have made booming, low-frequency sounds like both crocodiles and ostriches do. But scientists do think they know what one dinosaur sounded like. The duck-billed dinosaur likely sounded something like a didgeridoo when it breathed, based on the shape of its head. In 1997's Jurassic Park: The Lost World, the filmmakers recorded cows as stand-ins for the duck-billed dinos. The noises are in the same ballpark, but they're definitely more high pitched.

It turns out, movies about raising extinct species aren’t always scientifically accurate. Listen to the dino sounds (both scientific and Hollywood-produced) for yourself:

[h/t The Verge]