They are usually depicted with their razor-sharp teeth while chasing down unfortunate prey.

But the T-Rex may not have looked so alarming in real life, according to new research.

Scientists have discovered that the dinosaurs had scaly, lizard-like lips that covered and sealed their mouths.

And while that would still have been a terrifying sight, it suggests they were misrepresented in films like Jurassic Park, the study found.

Theropod dinosaurs, a group of two-legged dinosaurs that includes both the Velociraptor and birds, used to have lipless mouths with visible upper teeth hanging over their lower jaws, similar to a crocodile’s mouth.

Scientists have discovered that T.Rex had scaly, lizard-like lips that covered and sealed their mouths

They are usually depicted with their razor-sharp teeth while chasing down unfortunate prey. But the T-Rex may not have looked so alarming in real life, according to new research

But an international team of researchers now believe these dinosaurs had lips similar to those of lizards and their relatives, the tuatara – a rare reptile found only in New Zealand.

Researchers studied the tooth structure, wear patterns and jaw morphology of groups of reptiles with and without lips and found that the anatomy and functionality of theropod mouths resembled those of lizards rather than crocodiles.

They said this implies lizard-like mouth tissues, including scaly lips covering the teeth.

The researchers said these lips were probably not muscular like they are in mammals, since most reptilian lips cover their teeth but cannot be moved independently or rolled back into a snarl.

co-author dr. Mark Witton of the University of Portsmouth said: “Since we started dinosaur restorations in the 19th century, dinosaur artists have gone back and forth on lips, but lipless dinosaurs became more popular in the 1980s and 1990s.

“They were then deeply ingrained in popular culture through movies and documentaries – Jurassic Park and its sequels, Walking With Dinosaurs and so on.

“Interestingly, there was never a specific study or discovery that prompted this change, and in large part it likely reflected a preference for a new, wild-looking aesthetic rather than a shift in scientific thinking.

“We turn this popular representation on its head by covering her teeth with lizard-like lips.

The researchers said the lips probably aren’t muscular like they are in mammals, since most reptilian lips cover their teeth but can’t be moved independently or rolled back into a snarl

A full-lipped adolescent tyrannosaurus runs over Struthiomimus, a beaked ostrich dinosaur

“This means many of our favorite dinosaur depictions are wrong, including the iconic Jurassic Park T-Rex.”

The results, published in the journal Science, showed that dinosaur teeth were no larger than those of modern lizards relative to skull size, suggesting they were not too large to be covered with lips.

Thomas Cullen, assistant professor of paleobiology at Auburn University and lead author of the study, said: “Although it has been argued in the past that predatory dinosaur teeth may be too large to be covered by lips, our study shows that in reality theirs Teeth were not unusually large.

“Even the huge teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards compared to skull size, belying the notion that their teeth were too large for lips to cover.”

The researchers point out that their study does not claim that no extinct animals had exposed teeth.

Some, like carnivorous saber-toothed mammals or marine reptiles and flying reptiles with extremely long, interlocking teeth, almost certainly did.

Dinosaurs ruled and dominated the Earth about 66 million years ago before suddenly becoming extinct.

This mass extinction is known as the Cretaceous-Tertiary extinction.

For many years it was believed that climate change was destroying the giant reptiles’ food chain.

In the 1980s, paleontologists discovered a layer of iridium.

This is an element that is rare on Earth but found in large quantities in space.

When this was dated, it coincided exactly with the time when dinosaurs disappeared from the fossil record.

A decade later, scientists discovered the massive Chicxulub Crater at the tip of Mexico’s Yucatán Peninsula, dating from the period in question.

The scientific consensus now says that these two factors are linked and both were likely caused by a giant asteroid crashing into Earth.

With the projected size and impact speed, the collision would have created an enormous shock wave and likely triggered seismic activity.

The fallout would have created plumes of ash that likely covered the entire planet, making it impossible for the dinosaurs to survive.

Other animal and plant species had a shorter span of time between generations, which allowed them to survive.

There are several other theories as to what caused the demise of the famous animals.

One early theory was that small mammals ate dinosaur eggs, and another proposes that toxic angiosperms (flowering plants) killed them.