Paleontologists from Seattle's Burke Museum have unearthed an extremely rare Tyrannosaurus rex fossil during an expedition in Montana's Hell Creek Formation.

The remains, which earned the nickname "Tufts-Love Rex" after the volunteers who discovered it, include about 20 percent of the animal: a near-complete skull, ribs, lower jaw bones, hips and vertebrae. The special discovery may provide experts more insight into the prehistoric creature.

Tufts-Love Rex

During the expedition, two researchers initially discovered fragments of the fossilized bone sticking out of a rocky hillside on federal land. The bones' honeycomb-like structure and large size suggested that they were parts of a carnivorous dinosaur.

Upon further investigation, the team discovered the near-complete skull along with its other body parts. The near-complete skull is about 4 feet (121 centimeters) long and around 2,500 pounds (1,133 kilograms) in mass.

However, only the right side of the skull is present. Scientists believe it is possible that the left side is there, but they will have to remove the rock around the fossil to assess its completeness.

Burke scientists estimate that the 66.3 million-year-old Tufts-Love Rex is approximately 85 percent of the biggest T. rex ever found to date. The T. rex would have been almost as tall as a city bus at the hips and as long as a bus from head to tail.

The dinosaur had lived during the end of the Cretaceous Epoch and was wiped out during the Cretaceous-Paleogene mass extinction event. Researchers knew this because the fossil was found at the bottom of the hill — a layer that marked the extinction event.

Furthermore, based on the dinosaur's skull, paleontologists estimate that the T. rex must have been 15 years old when it died.

Gregory P. Wilson, a curator at the museum and biology professor at University of Washington, believes that the Tufts-Love Rex will become an iconic specimen for Washington and the Burke Museum, as well as a must-see for dinosaur researchers.

Although the T. rex is one of the most famous dinosaurs ever, its fossils are hard to find. The Burke Museum team's discovery is one of only 25 fossils with such level of completeness. Its skull is the 15th reasonably complete skull to exist in the world.

“I think it’s a real paradox that it’s the iconic dinosaur of toy sets and movies, but we have so few of them,” Wilson tells The Christian Science Monitor.

Next summer, Wilson and colleagues will hunt for additional parts of Tufts-Love Rex at the fossil site. In the meantime, the dinosaur will be displayed at the Burke Museum from Aug. 20 to Oct. 2.