Tyrannosaurus, sharp teeth between closed mouths? In fact, it was not visible through the lips.

The Tyrannosaurus in the film shows its large, sharp teeth even when its mouth is closed. However, a new study suggests that Tyrannosaurus, like lizards, would hide their teeth behind their lips if they kept their mouths closed.

Researchers at Auburn University in the United States said, “Similar to today’s Komodo dragons, dinosaurs would have had soft tissues around their mouths that functioned as lips,” reported an international journal, Science, on the 30th (local time).

The researchers analyzed fossil theropod skulls of reptiles and dinosaurs. Their upper jaws were examined for patterns of small holes through the bone. The hole connects blood vessels and nerves to the soft tissue around the mouth.

In lipless crocodiles, these holes are scattered throughout the mouth. However, in reptiles with lizard-like lips, the small holes were lined along the edge of the jaw near the teeth. Tyrannosaurus was analyzed to have a lizard-like burrow arrangement.

Tooth enamel (the hard outer layer of teeth) also provided clues that Tyrannosaurus may have had lips. Enamel wears off more easily when it dries. Alligators have thick enamel and retain moisture because they live in water, but more cracks develop on exposed surfaces. Theropods did not. Theropod teeth are covered with thin enamel, which has a uniform wear pattern. This suggests the possibility that dinosaurs had lips that protected teeth and were covered with saliva, the researchers explained.

A cousin of the extinct crocodile, Hesperosuchus, showed a neat arrangement of holes in its mouth. This suggests that early reptiles that gave birth to dinosaurs and crocodiles may have had lips. The researchers speculate that the lips may have been lost in the crocodile lineage that survived into modern times.