When a Tyrannosaurus rex or other carnivorous dinosaur is depicted on screen, it roars like a carnivorous mammal. But birds developed from dinosaurs, so could they have screeched or called like the modern cassowary, or made no noise at all?
Tony Holkham, Blaenffos, Pembrokeshire, UK
The same question occurred to me when I first saw Jurassic Park. Why would a stealth predator roar?
T. rex was a carnivore, and carnivores are usually only vocal when establishing territory or seeking a mate. Advertising their presence when hunting wouldn't be smart. The same goes for birds, which evolved from dinosaurs.
Mike Follows, Sutton Coldfield, West Midlands, UK
There is no way to be sure what T. rex sounded like because the soft tissues of its voice box haven't been fossilised.
The roar of the T. rex in Jurassic Park was created by combining sounds made by a baby elephant, alligator and tiger. But dinosaurs would have used sound not to frighten prey but to communicate.
Birds and crocodilians are the dinosaurs' nearest living relatives. Julia Clarke at the University of Texas has combined the booming cry of the Eurasian bittern (Botaurus stellaris) with sounds made by Chinese alligators (Alligator sinensis) to make a fearsome low-frequency rumble ideal for long-distance calling. The fossilised ear cavities of T. rex suggest they were sensitive to low-frequency sound.
Or maybe dinosaurs didn't have vocal organs and made vibrations in resonating chambers. This would have allowed them to make noises with their mouths closed, as birds and reptiles do.
Peter Jones, Wolfenbüttel, Germany
Those interested should check out the “Jurassic Squawk” episode of BBC Radio 4 series The Curious Cases of Rutherford & Fry, from May 2019. T. rex may not have had a larynx or had a mouth cavity suitable for vocalisation. Its branch of dinosaurs evolved into birds, which use a different organ, the syrinx, to make sounds, but this developed later. Our best guess, based on closed-mouth vocalisation similar to modern crocodiles, is that they made an underwhelming low-pitched hum. If you turn the volume up, it does sound a bit more threatening.
Richard Lucas, Camberley, Surrey, UK
The only dinosaur sound we have any confidence in is that of the Parasaurolophus. Its bony, crested skull held tubes connected to its nasal passages that would have been used to make a sound like a trombone. Birds use a thoracic organ called a syrinx to form their calls. A late-age dinosaur fossil complete with syrinx has recently been found in Antarctica.
Hazera Forth, Bedford, UK
This is why my 10-year-old and I cluck when a T. rex appears in any scene of the Jurassic Park franchise. It is hilarious.