Ankylosaurs used their hammer tails to fight each other

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Armored dinosaurs called ankylosaurs may have wielded hammer-like tail clubs against each other in conflict, as well as warding off predators like the Tyrannosaurus rex.

A well-preserved fossil of an ankylosaurus, 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 the fossil revealed spikes on the dinosaur’s flanks that broke and healed while the animal was still alive. Researchers believe the wounds were caused when another ankylosaur slammed its tail into the dinosaur.

The study was published Tuesday in the journal Biology cards.

The ankylosaurus had bony plates of different sizes and shapes along its body; along the sides of its body, these plates acted as large spikes. Scientists also believe that ankylosaurs could have used their weapon-like tails to assert social dominance, establish their territory, or even while fighting for their mates.

An ankylosaur using its tail in combat with each other is similar to how animals such as deer and antelope use their horns and antlers to fight each other today.

The fossil is of a member of a particular species of ankylosaurus, otherwise known by its taxonomic name, The roar that curdles blood. If the name sounds familiar, it’s because the researchers borrowed the Zuul name from a monster in the 1984 movie “Ghostbusters.”

The dinosaur’s full name means “Zuul, the destroyer of shins,” since the ankylosaurus’ club tail is thought to have been the enemy of tyrannosaurs and other predators that walked upright on their hind legs.

These tails were up to 10 feet (3 meters) long, with rows of sharp spikes on the sides. The tip of the tail was fortified with bony structures, creating a club that could be swung with the force of a hammer.

The skull and tail were the first pieces of the fossil to emerge in 2017 from a dig site in the Judith River Formation in northern Montana, 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 on the dinosaur’s back and flanks, giving it a very realistic appearance.

This particular ankylosaurus looked pretty broken up at the end of its life, with spikes near its hips and spikeless sides. After sustaining these injuries, the bone healed in a much stronger form.

Because of the location on the body, researchers do not believe the wounds were caused by a predator attack. Instead, the pattern appears to be the result of receiving a blunt blow 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 lead study author Dr. Victoria Arbour, 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 hit an opponent really hard, but most people thought they were using their tail clubs to fight off predators. Instead, ankylosaurs like Zuul can have been fighting each other.”

Arbour hypothesized that ankylosaurs might have been involved in their behavior years ago, but fossil evidence of injuries was needed, and ankylosaur fossils are rare.

The exceptional crurivastator fossil Zuul helped fill this knowledge gap.

“The fact that the skin and armor are preserved in place is like a snapshot of what Zuul looked like when he was alive. And the injuries Zuul suffered during his life tell us how he behaved and interacted with other animals in their ancient environment,” said study co-author Dr. David Evans, Temerty Chair and Curator of Vertebrate Paleontology at the Royal Ontario Museum in Toronto. in a statement.

The Zuul fossil is currently housed in the Royal Ontario Museum’s Vertebrate Fossil Collection.