“It has this very short, broad snout, and then it has these two sets of horns that project backwards from the eye; one above the eye and one a little bit further down. And that’s exactly what we see in the skull of this dinosaur.”
Research on the new species, led by Arbour, was published in the May issue of the Royal Society OpenScience journal.
Zuul, the dinosaur, is about 75 million years old. Its body was found in a river deposit in Montana’s Judith River Formation and spanned about six metres long.
The dinosaur’s skeleton was found almost entirely intact, according to Evans, noting it was “remarkably preserved” under 10 metres of rock.
“This is a dinosaur that would not have been exposed for paleontologists to find for probably hundreds of years, maybe thousands of years,” he said. “The fossil was never exposed to modern erosion or plant roots . . . so that means we have a level of preservation that is jaw-dropping.”
The skeleton had to be broken up into several pieces in order to be removed. Zuul likely weighed about 5,500 pounds, equivalent to the size of a white rhinoceros.
“This is very rare, to find a complete articulated skeleton, especially for this group of dinosaurs,” Arbour said. “They’re just not as common.”
Its species name, crurivastator, means “destroyer of shins,” a reference to a large knob of bone at the tip of its tail, which may have been used to strike the legs of predatory dinosaurs in defence, or for battle during contests for mates.
Researchers have preserved the large, sharp bony spikes that formed in Zuul’s skin over its tail and likely the entirety of its body, forming its armour. They also managed to maintain very rare keratin sheaths — the same material which forms finger nails, bird beaks and the top of turtle shells — and soft tissues such as its scales.
While the dinosaur’s colour is unknown, Evans said they believe it may have been brightly coloured due to its outer keratin layer.