The terrifying velociraptors that ripped apart everyone they could catch in Jurassic Park should have been given feathers by the director Steven Spielberg.

Researchers now say that the dinosaurs, which leapt into the public imagination when they were featured in the hit 1993 film, were misrepresented. After analysing fossilised bones they have discovered that the velociraptor was not the smooth-skinned creature portrayed in the film, but had feathers.

The discovery means that as well as being more decorative than the creatures that appeared in the film they could have been an even more terrifying predator because the feathers would probably have been improved their manoeuvrability.

Scientists have suspected for several years that velociraptors were feathered beasts, but only now have they been able to identify what they believe is conclusive proof. Close analysis of a velociraptor forelimb unearthed in Mongolia in 1998 reveals that quill knobs were present on the fossilised bone. Quill knobs, which are found on many modern bird species, are where the flight or wing feathers are anchored to the bone by ligaments.

“A lack of quill knobs does not necessarily mean that a dinosaur did not have feathers,” said Alan Turner, of the American Museum of Natural History, and the lead author of the study. “Finding quill knobs on velociraptor, though, means that it definitely had feathers. This is something we’d long suspected but no one had been able to prove.”

Velociraptors had short forelimbs compared with modern birds’ wings, which has led researchers to conclude that they were flight-less but had probably descended from an extinct creature that had been able to fly. That the velociraptors had retained at least some feathers suggests that they continued to have a role, even if not for flight.

The researchers said that one of the most likely functions of the feathers was to display to other velociraptors, perhaps in courtship rituals or as a show of strength against aggressors. Other functions could have included use as a shield to protect eggs, a temperature control to prevent the dinosaurs from getting too hot or cold, or to help them to manoeuvre while running.

Mark Norell, one of the researchers from the American Museum of Natural History, said: “The more that we learn about these animals the more we find that there is basically no difference between birds and their closely related dinosaur ancestors like velociraptor. Both have wishbones, brooded their nests, possess hollow bones and were covered in feathers. If animals like velociraptor were alive today our first impression would be that they were just very unusual looking birds.”

The fossil analysed for the study came from a velociraptor that was estimated to have been 5ft (1.5m) long, 3ft tall and weighing 33lb (15kg) when it died.

The research was a joint project of the American Museum of Natural History, New York, and the Field Museum, Chicago. In their report the authors say: “We present direct evidence of feathers in Velociraptor mongoliensis based on the presence of quill knobs on the posterior forearm. Their absence does not necessarily indicate a lack of feathers. Their presence, however, is a direct indicator of feathers.”

The six quill knobs were found spaced about 0.16 inches (4mm) apart and the researchers estimated that the limb would have had 14 secondary feathers on the forearm, similar to the 12 in Archaeopteryx, which is the earliest known bird.

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