In 2014, paleontologists discovered a new type of ankylosaur, the armored dinosaur beloved of adolescent boys around the world.
This species had a distinctive skull and a sledgehammer tail. When Dr. Victoria Arbour, a paleontologist at the Royal BC Museum in British Columbia, first saw the horny head, she immediately thought of Zuul, the demon dog from “Ghostbusters”.
And that’s how the species gained its unique name: Zuul crurivastator, or “Zuul, the destroyer of shins”.
Commercial fossil hunters first discovered the ancient animal’s remains by accident in Montana’s Judith River Formation. When the Royal Ontario Museum acquired this rare find, most of the creature’s skeleton remained in a massive block of sandstone.
It took over a year for excavators to painstakingly remove its bones from the surrounding rock. Eventually, the museum’s paleontologists found themselves with one of the most complete ankylosaur skeletons ever discovered. (The original species of ankylosaurus, while famous, remains extremely rare, with no complete skeleton ever found.)
After analyzing Zuul’s skeleton, Arbour and her colleagues were able to speculate about the animal’s behavior 76 million years ago.
It turns out that these tank-like giants didn’t only use their powerful tails to break the shins of predators like Tyrannosaurus rex. They may also have used them in mating rituals, according to a new study Arbour and her colleagues published this week.
An illustration and photo of the Zuul crurivastator specimen’s injuries, with its injured spikes in red. Images: Royal Ontario Museum
Decoding an embattled skeleton
Once researchers had fully removed the Zuul’s skeleton, they could see fossilized skin covered with osteoderms, or bony deposits.
Along the dino’s backside, the museum’s experts discovered that certain spikes near the hips were missing their tips. Some of the bony sheaths encasing those osteoderms had broken and healed into blunt points.
It’s unlikely that predators would have tried to attack herbivorous tanks like Zuul from behind, where they were most likely to receive a blow from its lethal club-tail.
“The injuries are right where you’d expect two battling ankylosaurs would break things,” Arbour told The New York Times.
So it’s more likely that the injuries resulted from mating rituals not unlike modern deer or bighorn sheep butting heads to establish dominance. To attract mates, it’s possible these ancient armored beasts traded body blows with their tails.
“Ankylosaurs left no living descendants, so we have no living analogs to learn what ancient ankylosaurs did,” Jordan Mallon, a paleontologist at the Canadian Museum of Nature in Ottawa, told The New York Times. “This is the first example where we’ve been able to marshal some evidence to support that these things were actually using their tail clubs to smash into one another in a ritualistic way.”
