The remarkable discovery includes the dinosaur's vertebrae, ribs, hips and lower jaw bones, and represents about 20% of the meat-eating predator.

Several dozen scientists, volunteers, students and others worked over the summer to excavate the bones in the Hell Creek Formation in Montana, a site well known for fossil finds.

The team later encased the massive skull in a protective plaster cast, lifted the 2,500lb load onto a flatbed truck with the help of local Montana ranchers and drove it to Seattle. The skull, which is four feet long, was unloaded at the city's Burke Museum on Thursday.

The plaster-covered skull will be on display to the public for several weeks starting on Saturday. Over the next year, paleontologists will painstakingly work on removing the rock around the skull.

Scientists estimate the dinosaur is 85% the size of the largest Tyrannosaurus rex discovered and, based on the size of its skull, lived about 15 years.

They believe it roamed the earth in the late Cretaceous period.

Only 14 other nearly complete Tyrannosaurus rex skulls have been found, the museum said.

"We think the Tufts-Love Rex is going to be an iconic specimen for the Burke Museum and the state of Washington and will be a must-see for dinosaur researchers as well," said Gregory Wilson, who led the expedition team.

The T. rex is named after two museum paleontology volunteers, Jason Love and Luke Tufts, who came across large fossilised vertebrae sticking out of a rocky hillside last summer.

They were with a team collecting fossils as part of the Hell Creek Project, currently led by Mr Wilson and started by Jack Horner, who discovered the world's first dinosaur embryos, and Nathan Myhrvold, former Microsoft chief technology officer who is a Burke Museum research associate.

The team knew the fossils belonged to a meat-eating dinosaur because of the large size and appearance of the bones, but they were not sure whether it was a T. rex.

They did not have the chance to excavate further until this summer when they returned to the site.

Over the course of a month, Burke paleontologists and others used tools such as jackhammers, axes and shovels to dig up the bones.

Scientists think the rest of the skull is there as well. They plan to return to the site next year to search for that and other dinosaur parts.

Mr Horner said the discovery was "one of the most significant specimens yet found".