Ankylosaurs used their sledgehammer tails to fight each other
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Armored dinosaurs, called ankylosaurs, may have used sledgehammer-like tail maces against each other in conflict, in addition to fighting off predators such as Tyrannosaurus rex.
A well-preserved fossil of an ankylosaur, a herbivorous 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 the fossil revealed spikes on the dinosaur’s flanks that had broken and healed while the animal was alive. Researchers believe the injuries were caused when another ankylosaurus slammed its tail club into the dinosaur.
That’s according to a study published Tuesday in the journal Biology Letters.
Ankylosaurus bore bony plates of various sizes and shapes all over its body; along the sides of its body, these plates acted like large spikes. Scientists also believe that ankylosaurs may have used their weapon-like tails to assert social dominance, establish territory, or even while fighting for mates.
An ankylosaur using its tail to fight each other is similar to how animals such as deer and antelope use their antlers and horns to fight each other today.
The fossil is of a member of a certain species of ankylosaur, otherwise known by its classification name, The bloodcurdling roar. If the name sounds familiar, it’s because researchers borrowed the name Zuul from a monster in the 1984 movie “Ghostbusters.”
The dinosaur’s full name means “Zul, the Destroyer of the Shins,” since the Ankylosaurus’ tail club is believed to have been the enemy of tyrannosaurs and other predators that walked upright on their hind legs.
These tails were up to 3 meters long, with rows of sharp spines along the sides. The tip of the tail was reinforced with bony structures, creating a club that could swing with the power of a sledgehammer.
The skull and tail were the first pieces of the fossil to emerge from a dig site in northern Montana’s Judith River Formation in 2017, and paleontologists worked for years to free the rest of the fossil from 35,000 pounds of sandstone. The fossil was so well preserved that remnants of skin and bony armor remain across the dinosaur’s back and flanks, making it look very lifelike.
This particular ankylosaur looked pretty beat up at the end of its life, with spines near its hips and sides with missing ends. After sustaining these injuries, the bone healed into a much blunt shape.
Due to its location on the body, investigators do not believe the injuries were caused by a predator attack. Instead, the pattern resembles the result of a powerful blow from another ankylosaurus’ tail club.
“I’ve been interested for years in how ankylosaurs used their tail clubs and this is a really exciting new piece of the puzzle,” said lead study author Dr. Victoria Arbor, curator of paleontology at the Royal British Columbia Museum in Victoria, Canada. , in a statement.
“We know that ankylosaurs could use their tail clubs to deliver very powerful blows to an opponent, but most people thought they used their tail clubs to fight off predators. Instead, ankylosaurs like Zuul may have fought each other.”
Arbor suggested the hypothesis that ankylosaurs may have engaged in their behavior years ago, but fossil evidence of injuries was needed—and ankylosaur fossils are rare.
The exceptional Zuul crurivastator fossil helped fill that knowledge gap.
“The fact that the skin and armor are kept in place is like a snapshot of what Zuul looked like when he was alive. And the injuries Zuul sustained in his lifetime tell us how he may have behaved and interacted with other animals in his ancient environment,” said study co-author Dr. David Evans, Temerty president and curator of paleontology. of vertebrates at the Royal Ontario Museum in Toronto, in a statement.
The Zuul fossil is currently held in the collection of vertebrate fossils at the Royal Ontario Museum.
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