On the second floor of Toronto's Royal Ontario Museum, the skeleton of an older, ganglier cousin of Tyrannosaurus rex stands tall. But if the creature were alive today, it might be limping. More than 70 million years ago, this Gorgosaurus would have been an apex predator in what are now the badlands of Montana and western Canada. Apex doesn't mean invincible, though. The animal's right shin is a mess of broken bone that healed over in life.

What broke the poor tyrannosaur's leg? Short of hopping in a time machine, researchers can't be sure. But elsewhere in the same museum, visitors can get a glimpse of one of the best—and most exquisite—suspects in this Cretaceous cold case.

Meet Zuul crurivastator, a new species of ankylosaurid that's also the most complete fossil of its kind ever found in North America. In life, the animal was a 20-foot-long living tank bristling with armor and weighing as much as a white rhinoceros. In death, its hulking fossil is amazingly well-preserved from its snout to its sledgehammer-like tail—the perfect weapon for delivering bone-shattering damage.

While Zuul's discovery was announced in May 2017, the fossil skull and tail were unveiled to the public on December 15 as part of a new museum exhibit. It's a multimedia extravaganza, featuring a full-size model of the fossil, a huge animation of Zuul in action, and even educational arcade games. (See pictures from an exhibit in New York that showcased dinosaurs in all their feathered glory.)

The rest of the fossil is still being unlocked from its sandstone tomb in a much more sedate warehouse about a hundred miles east of the museum. On a chilly December morning a few days before the unveiling, I visit this facility, owned by Research Casting International, a museum exhibits firm in Trenton, Ontario. As snow gently falls outside, RCI president Peter May ushers me into the main workspace. The sour smell of polyester resin cuts the air as ventilators rumble in the background.

May whisks me down the warehouse's main corridor to a brown tent shielding what looks like a concrete-filled sandbox. Four technicians in dusty blue smocks lie atop the block, buzzing away with tiny handheld jackhammers. Millimeter by millimeter, the needle-tipped tools reveal brownish mineral patches. To my astonishment, the leathery pebbles are bits of armor and individual scales.

Releasing this unusually detailed fossil is achingly precise work, but it will be well worth it. Ankylosaur fossils are rare, and even when they are found, they're often scattered like puzzle pieces due to the decay process. With Zuul, it's almost as if the whole animal was instantly turned to stone.

“It's among the very, very best-in-class of specimens out there,” says paleontologist Victoria Arbour, a curator at Canada's Royal BC Museum and an ankylosaur expert. Already, the scientists can see broken armor along its flank, a clue that Zuul sustained battle damage from other ankylosaurids.

“The quality of the armor and skin preservation has exceeded our wildest dreams,” adds Royal Ontario Museum paleontologist David Evans, who is studying the dinosaur.

Crossing the streams

When Arbour and Evans first announced Zuul, the find made headlines around the world. But in a twist of fate, they weren't the only Canadian paleontologists with a dinosaur to show off that week. Within days, Alberta's Royal Tyrrell Museum unveiled its own remarkable armored dinosaur, a new species later named Borealopelta markmitchelli. (Read more about Borealopelta in National Geographic magazine.)



Related: Dinosaur fossil is best preserved of its kind Discovered by miners in Alberta, Canada, the fossil Borealopelta markmitchelli is the best-preserved nodosaurid, a type of armored dinosaur, ever found. When it was alive 110 million years ago, it was 18 feet long and weighed nearly 3,000 pounds. Unlike Zuul, Borealopelta didn't have a tail club. Instead, it had two 20-inch-long spikes on its shoulders.



At first glance, the pair may evoke dino déjà vu, but they are very different animals. Borealopelta lived a full 35 million years earlier, and unlike Zuul, it didn't have a tail club. Borealopelta also was found years before Zuul, giving its caretakers a head start in preparing the fossil. In 2017, the world could see Borealopelta in all its glory, but at the time, Zuul's trip back to sunlight was only just beginning.



Zuul began its march to immortality 76 million years ago, near a lush estuary in what's now northern Montana. Ferns and cousins of sycamore trees swayed in the wind, as crocodiles and turtles lurked beneath the water. Somehow, Zuul ended up dead in a river's shallows. As its carcass bloated and floated belly-up, it got caught in a logjam and meandered into an eddy. Waves of sand quickly secured most—but maybe not all—of the fossil. Researchers still haven't found Zuul's limbs, which scavengers may have gobbled up like dino kebabs.

Once entombed, the dinosaur transformed into a golem, as iron-rich minerals preserved its flesh and bone. Some 40 feet of rock then piled atop Zuul's sandstone cocoon, and the eroding hillsides never came within 30 feet of the fossil. Eventually, the land above Zuul became a private ranch just south of the U.S.-Canada border.

In 2014, commercial fossil collectors with a company called Theropoda started digging there to excavate the scattered bones of a Gorgosaurus. As the crew followed the skeleton down through a hundred feet of dirt, they struck hard sandstone. Suddenly, one excavator shouted, “This thing's an alien!” He was staring at something that definitely didn't belong to a tyrannosaur: an ankylosaurid's tail club.

Despite marketing many of its fossils to private collectors, the Theropoda crew knew that Zuul was special and that it had to enter the public trust. Soon after finding it, the company contacted Evans, who urged the Royal Ontario Museum to acquire the fossil in 2016. (Learn more about the fossil trade in National Geographic magazine.)

“This is how the system should work,” says Tommy Heitkamp, Theropoda's director of operations.

Who you gonna call?

For Arbour, Zuul's move to Canada presented a dream opportunity. In a stroke of luck, she was starting a two-year stint at the museum just as the fossil arrived. As she and Evans began studying the dinosaur's skull and tail, which had already been freed from rock, they realized the dinosaur was a newly seen kind of ankylosaurid.

To honor the animal's weaponized tail, the pair picked the species name crurivastator, Latin for “destroyer of shins.” As for the genus name, its horns reminded Arbour of Zuul, the hellhound from the 1984 film Ghostbusters. To make the name official, Evans sought the blessing of a friend of his: paleontology enthusiast Dan Aykroyd, the movie's costar and cowriter. Aykroyd enthusiastically agreed.

Meanwhile, the 20-ton block containing Zuul's body sat in RCI's warehouse, a silent reminder of the mammoth task ahead. Even getting it inside had been a challenge: The fossil was so heavy, the forklift holding it sank into the parking lot.

The block stood untouched until January 2018, when preparators started working to expose Zuul's spine and ribcage. Eight months later, they were ready to tackle the dinosaur's back armor, requiring RCI to cut the block in half and then flip it over like a 17,000-pound pancake.

Ever since, preparator Amelia Madill and her team have painstakingly revealed Zuul's armor. These five women now know the magnitude of the find better than anyone. “When the block arrived, I talked to my dad about it, and I said, Well, that's somebody's life's work right there,” Madill says. “It's an amazing job; it's unreal.”

Zuul is so unreal, it's put RCI behind schedule. It will take Madill's team until the end of 2018 to finish their work, if not longer. Only then will the fossil's scientific story really begin—including chemical searches for some of the dinosaur's original proteins.

Back in the Royal Ontario Museum, the undisputed star of the new exhibit sits within a Plexiglas box: the skull of Zuul, its mouth agape, its brow perpetually furrowed. Staring at the creature, it almost seems to stare back, until I feel like I'm sensing the daily life it enjoyed 76 million years ago. These jaws once munched on Mesozoic meadows. These eyes with their bony lids once gazed out on a lost world.