The Tyrannosaurus rex, one of the most iconic dinosaurs, is often depicted with sharp, protruding teeth. But a new study suggests that these teeth may have been covered by lips, which would have given the T. rex a more subdued appearance.

The study, published in the journal Current Biology, analyzed the fossilized remains of several T. rex skulls. The researchers found that the T. rex had a thick layer of soft tissue on its snout, which would have been sufficient to cover its teeth.

This finding is significant because it challenges the traditional view of the T. rex as a fearsome predator with a menacing grin. Instead, the T. rex may have had a more gentle appearance, with its lips covering its teeth.

The researchers believe that the T. rex's lips may have served several functions. One possibility is that they helped to protect the T. rex's teeth from damage. Another possibility is that they helped to keep the T. rex's mouth moist, which would have been important for preventing its teeth from drying out and becoming brittle.

The study's findings provide new insights into the appearance and behavior of the T. rex. They suggest that the T. rex may have been a more complex and adaptable creature than previously thought.

Here are some additional details about the study:

* The researchers analyzed the fossilized remains of eight T. rex skulls.

* The T. rex skulls were found in the Hell Creek Formation in Montana and Wyoming.

* The T. rex lived in North America during the late Cretaceous period, about 68 million years ago.

* The T. rex was one of the largest carnivorous dinosaurs, reaching lengths of up to 40 feet and weighing up to 15 tons.

* The T. rex's teeth were up to 8 inches long and were designed for crushing bone.

The study's findings have been met with some skepticism from other paleontologists. Some paleontologists believe that the T. rex's lips may have been too thin to cover its teeth. Others believe that the T. rex's lips may have been present only in certain situations, such as when the T. rex was resting.

Despite the skepticism, the study's findings provide a new perspective on the T. rex. They suggest that the T. rex may have been a more complex and adaptable creature than previously thought.