SEATTLE – With magnifying lenses covering his eyes and a “jackhammer” the size of an electric toothbrush cleaning 66 million-year-old sandstone from the massive skull of one of the greatest predators the world ever knew, Bruce Crowley is “in the zone.”

On the other side of the special enclosure’s windows, visitors to Seattle’s Burke Museum strain to see the emerging shape of the Tufts-Love Tyrannosaurus rex skull. Every so often, paleontologist Crowley or another member of the crew bending over the huge block of plaster, rock and bone turns to wave and smile at faces pressed up against the glass. Then they bend back to their work under bright lights and magnifiers.

Some would find it tedious, removing eons of geologic packing from an animal that roamed what’s now eastern Montana at the end of the Cretaceous period, maybe a few hundred thousand years before a mass-extinction event wiped dinosaurs from the face of the earth. For Crowley, the Burke’s head of fossil preparation, it’s the stuff of dreams.

“The tools and the techniques aren’t that hard to learn. Proficiency takes a while,” he said after wiping a bit of fine sand from the antorbital fenestra, a large opening in the skull below the eye socket. “Having the right temperament is the key.”

Crowley and others will be at it for at least six months, maybe a year, before the cleaned and preserved skull will be ready to display. In the meantime, visitors to the state’s oldest museum are able to watch their progress on what’s expected to be one of the world’s best preserved T. rex skulls.

When the enlarged museum opens in 2019, Tufts-Love will have a place of prominence, and the type of interaction between curators and visitors being pioneered with the cleaning of the skull will be a main feature of the new facility.

Big head, lots of teeth, short arms: You know this dinosaur

Despite being dead as long as it has, the Tyrannosaurus rex, with its giant head, small arms and powerful back legs is one of the most recognizable dinosaurs known. Forget the movies: they lived in the Cretaceous, not the Jurassic, period from about 145 million years ago to about 66 million years ago, when the age of dinosaurs came to an abrupt end, geologically speaking, possibly from a comet or a meteor striking the earth.

A T. rex was big, about as long as a school bus on its end when standing up on its back legs, said Christian Sidor, curator of vertebrate paleontology at Burke. But it and other predator dinosaurs had adaptations to cut down on their weight, including honeycomb structures in their vertebrae and other bones, and large openings in the skull, known as fenestras, which is Latin for windows.

They are assumed to be pretty fierce predators. T. rex teeth have been found embedded in Triceratops fossils. They had short arms for their body size, about the length of a human arm. The arms are the subject of some jokes and longstanding debate on what they were for.

Likely an evolutionary adaptation, Sidor said, because T. rexes are not the only dinosaurs with that feature. The honeycombed bone structure is believed to be a preadaptation for flight in dinosaurs’ evolutionary descendents, birds.

While there are members of the tyrannosaurid family found in different places around the world, T. rexes are found in a relatively limited geographical area between Alberta and Wyoming.

Shortened walk pays off

Jason Love and Luke Tufts were on their last day of fossil prospecting in northeastern Montana in the summer of 2015 when decided to change their hiking plans. It had already been a successful summer. Earlier they had found the vertebrae of a thescelosauras, a small dinosaur from the Cretaceous, so they opted for a shorter route because Tufts’ ankle was bothering him.

A self-taught fossil prospector, Love had been going to Eastern Montana for about 15 years to indulge his passion. A century ago, collectors used to hire “bone hunters” to locate fossils that would later be excavated. But Love and Tufts are unpaid volunteers for the Burke.

In the Hell Creek Formation, one of the most important fossil sites in the world, they found a vertebra which “didn’t look that impressive.”

But it did have the characteristic honeycombed feature of a predator dinosaur. They scouted the area, discovered some other bones protruding from the hillside and recorded its location on the GPS. The Burke obtained an excavation permit from the Bureau of Land Management, the federal agency that oversees that land, for the next summer. That team discovered the skull, along with ribs, vertebrae, the pelvis and parts of the jaw.

They decided to name the fossil for the two volunteers who located the site.

When one of the excavating crew texted Love a photo of a tooth, “I knew it was a big deal,” he said. The skull and some of the surrounding rock were excavated, and all of it was covered in a thick layer of plaster to protect it for the trip back to Seattle.

“It’s like we bought a lottery ticket and two years later it got cashed in,” he said recently while watching the crew slowly strip away the plaster and rock from the skull.

A teenage T. rex

A full-grown T. rex weighed about 9 tons, and even reduced to its fossilized bones, it’s still a massive creature. Tufts-Love was probably about 15 years old, not quite full grown, and the Burke is storing parts of its plaster-encased bones all over the facility and in some long-term storage areas. It has about 90 bones, which would be about 30 percent of a full skeleton, but still in the top 10 of most complete T. rexes.

Paleontologists don’t know how Tufts-Love died, but they do know approximately when it died. It was found 30 meters below a geological layer in Hell Creek formation that was formed by the event that caused dinosaurs’ extinction 66 million years ago, so they estimate it died about 300,000 years before that happened, Sidor said. It likely fell in to a riverbed and was covered by sand.

They also don’t know if Tufts-Love was male or female. Before they laid eggs, female dinosaurs usually stored calcium in their bones, but short of that, “there’s no good way to determine sex yet in a T. rex,” he said.

Some dinosaurs have hundreds of fossilized skeletons found, and scientist have been able to draw many conclusions about their lives and habits. There are only about a dozen good T. rex skeletons in existence , and that’s not enough to determine many things about it, he said.

When the Tufts-Love skull and its other skeleton parts have been cleaned and restored, they’ll be available for researchers to study as well as for visitors wanting to get a look at the dinosaurs and other fossils in the museum’s extensive collection.

When the new Burke opens in two years, it will be about two-thirds larger and have more display space for those exhibits, Sidor said. It will also have an ongoing feature for the general public to watch museum staff as they clean and preserve items for display.

In the meantime, Crowley and other volunteers will continue to slowly peel away the sandstone that formed around Tufts-Love eons ago to preserve it for 21st Century eyes, and the thick plaster that was wrapped around it to move it safely from eastern Montana to Seattle. The skull sits on a specially built carrier that allows it to be rotated as they work.

It weighs an estimated 3,000 pounds. It hasn’t been officially weighed, but it did tip a hay baler that was designed lift 2,000 pounds, Sidor said.

Museum officials won’t know how well preserved it will be for months, but just this week they discovered something they weren’t expecting. Inside the antorbital fenestra, an opening bigger than a fist, is a bone surrounded by the same crumbly sandstone as the rest of the skull.

The fenestra may have contained soft tissue or air, paleontologists aren’t sure. But they are sure it didn’t have bones. Whether the bone is a piece of Tufts-Love that moved in some shift of the riverbed sand, or is from another dinosaur, is mystery that will have to wait for later solving.