The dinosaur sounds in Jurassic World are a Hollywood fabrication, with palaeontologists in the dark as to how what noises the prehistoric creatures would have made.

Lindsey Zanno, an assistant research professor of palaeontology at North Carolina State University, told Live Science that it is very difficult to study dinosaur sounds.

Birds and crocodiles - modern descendants of dinosaurs – vocalise in very different ways. Birdsong is believed to be the basis of human speech. They make noise with their syrinx, a vocal organ in the trachea that vibrates at different frequencies at the same time.

Crocodiles, on the other hand, make growling noises even though they do not have vocal chords. They can make these rumbles before they even hatch, researchers have found in the past.

Terry Gates, a palaeontologist at the North Carolina Museum of Natural Sciences, told the website: "At some point, that had to evolve, and we don't know if it evolved only along the line of birds, or if it evolved before birds."

No direct evidence

Zanno explained: "Vertebrates usually vocalize with soft tissues, and soft tissues rarely preserve in the fossil record."

Some fossils help provide evidence of the sounds produced – crested duck-billed dinosaurs had hollow crests attached to their nasal passages that could have produced a specific sound.

The creature had a long tubular crest that went from its nose over its head then returned to the nose: "You're looking at about seven feet of tubing before the molecule of air ever actually enters the head," Gates said, adding this might have produced a sound "kind of like a trombone".

However, Mark Norell, the chair of palaeontology at the American Museum of Natural History in New York City, said we will never truly know what the dinosaurs sounded like: "I think we can safely say that they made noises, but we can't say what they sounded like."

He added that all work into dinosaur vocalisation is speculative as you cannot have direct evidence of how the soft tissue functioned, but conceded the invented sounds in Jurassic World are better than nothing.

"If they based it just on what we know [about] dinosaurs, it would be a pretty boring movie. We're learning more all of the time, but we can't reconstruct these animals and understand them in a way we understand living animals."