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Armored dinosaurs called ankylosaurs could wield sledgehammer-like tail clubs against each other in skirmishes, in addition to fending off predators like the Tyrannosaurus rex.
A well-preserved fossil of an ankylosaur, a plant-eating dinosaur that lived 76 million years ago, is changing the way scientists understand armored dinosaurs and how they used their tail clubs.
A study of fossils revealed spikes on the dinosaur’s flanks that broke and healed while the animal lived. Researchers believe the injuries occurred when another ankylosaur struck the dinosaur’s tail club.
The study was published in the journal Tuesday Biology Letters.
Ankylosaurs sported bony plates of various shapes and sizes throughout their bodies; On the side of its body, these plates acted like large spikes. Scientists also believe that ankylosaurs may have used their tails as weapons to assert social dominance, establish their territory, or even when fighting for mates.
Ankylosaurs used their tails to fight against each other, today animals like deer and antelope use their antlers and horns to fight each other.
The fossil is a member of a specific species of ankylosaur otherwise known in its taxonomy, zuul crurivastator. If the name sounds familiar, it’s because researchers borrowed the name Juul from a monster in the 1984 movie “Ghostbusters.”
The dinosaur’s full name means “juul, destroyer of shins,” because the ankylosaur’s tail club was thought to be an enemy of tyrants and other predators that walked upright on their hind legs.
These tails are up to 10 feet (3 m) long, with rows of sharp spikes on the sides. The tip of the tail was structured with bony structures, creating a club that could be swung with the force of a sledgehammer.
The skull and tail were the first pieces of fossils from a 2017 excavation site in northern Montana’s Judith River Formation, and paleontologists toiled for years to free the remains from 35,000 pounds of sandstone. The fossil was so well preserved that remnants of skin and bony armor remained across the dinosaur’s back and flanks, giving it a very lifelike appearance.
This particular ankylosaur appeared to be quite traumatized towards the end of its life, missing spikes near its hips and side tips. After sustaining these injuries, the bone healed in a much more blunt form.
Due to the position of the body, researchers do not believe the injuries were caused by a predator attack. Instead, the pattern looks like the result of receiving a forceful slam from another ankylosaur’s tail club.
“I’ve been interested in how ankylosaurs used their tail clubs for years, and this is a really exciting new piece of the puzzle,” said Dr. Victoria Arbor, curator of paleontology at the Royal British Columbia Museum in Victoria, Canada. , in a statement.
“We know that ankylosaurs used their tail clubs to hit opponents very hard, but most people thought they were using their tail clubs to fight off predators. Instead, ankylosaurs like Juul may have fought each other.”
Arbor suggested the hypothesis that ankylosaurs may have engaged in their behavior years earlier, but fossil evidence of injury was needed—and ankylosaur fossils are rare.
The exceptional zool crurivastator fossil helped fill that knowledge gap.
“Where the skin and armor are preserved is like a snapshot of what Juul looked like when he was alive. And the injuries that Zool endured during its lifetime tell us how it behaved and interacted with other animals in its ancient environment,” said study co-author Dr. David Evans, Curator and Temerty Chair of Vertebrate Paleontology at the Royal Ontario Museum in Toronto, in a statement.
The Zool fossil is currently housed in the Vertebrate Collection of the Royal Ontario Museum.
