Scientists are describing the discovery of the fossilized remains of a tyrannosaurus rex in southwestern Saskatchewan as one of the most significant paleontological finds in recent memory.

Paleontologists are cautiously optimistic they will have a full skeleton - one of only a dozen known in the world - when they have finished unearthing the remains by summer's end.The dinosaur was found in July 1991 by school principal Robert Gebhardt when something unusual caught his eye as he walked along a cow path on the side of a hill in southwestern Saskatchewan.

"I looked to my left and I thought it was a piece of ironstone," Gebhardt, principal of Eastend School near Shaunavon, said Wednesday. "It seemed a bit odd, reddish brown."

It was part of the jawbone of a 65 million-year-old tyrannosaurus rex embedded in the side of a hill.

"It's an extremely rare find," said Ron Borden, director of the Royal Saskatchewan Museum in Regina, which is overseeing the excavation.

Gebhardt was with paleontologists John Storer and Tim Tokaryk when he made his discovery.

"It was right by my left foot," he recalled. "I could have been looking the other way and missed it altogether.

"But it didn't fit in with the vegetation there because of the color. I thought it was a piece of rock. It was about the size of a large file folder. And then there was a cylindrical object the same color about a meter away. It turns out it was a tooth. About the size of a small banana."

Scientists began their dig earlier this month and have excavated the upper part of the skeleton, including several vertebrae, part of an upper jaw, some teeth and part of a leg. The fossilized remains are encrusted in ironstone.

Huge pieces of rock are being taken from the site by helicopter to a flatbed truck and then to the Regina museum. It could take scientists up to a year to separate the fossil remains from inside the rock, which built up in layers over millions of years, preserving the bones almost intact.

Scientists say the specimen appears to be a mature adult meat-eating dinosaur that was up to 45 feet long and nearly 18 feet tall. It could open its mouth about 3 feet, exposing 60 daggerlike teeth. It dates to the Cretaceous period, about 65 million years ago.

Storer said the discovery might represent one of the largest tyrannosaurus rex specimens ever unearthed. No one will know for certain until it is completely dug up, but Borden said the body and tail extend into the side of the hill, a good sign that it could be a complete skeleton.

The area has been a motherlode for fossilized mammal remains but has produced far fewer reptilian fossils, Borden said.

As well as generating international scientific interest, the latest find has also fed hopes of tourism development for this pristine south-west corner of the province.

Wednesday, staff at the Eastend Community Tourism Authority were answering the telephone with "The Valley of Hidden Secrets."