Ankylosaurs didn't just use their tail clubs to fight T-Rex

The club-tailed ankylosaurus is one of the most iconic dinosaurs, often depicted using its tail to bash away hungry tyrannosaurs - but it turns out their clubs had more than one use.

A fossil named Zuul crurivastator - after the monster Zuul in Ghostbusters - shows that the club may also have been used for bashing other ankylosaurs.

The 76-million-year-old, plant-eating dinosaur may have had complex behaviour, possibly battling for social and territorial dominance or even engaging in a "rutting" season for mates.

Lead author Dr. Victoria Arbour, Curator of Paleontology at the Royal BC Museum saidd, "I've been interested in how ankylosaurs used their tail clubs for years and this is a really exciting new piece of the puzzle.”

"We know that ankylosaurs could use their tail clubs to deliver very strong blows to an opponent, but most people thought they were using their tail clubs to fight predators. Instead, ankylosaurs like Zuul may have been fighting each other."

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The fossil of the ankylosaur Zuul crurivastator has spikes along its flanks that were broken and re-healed while the dinosaur was alive—injuries that the scientists think were caused from a strike by another Zuul's massive tail club. T

The research is published in the journal Biology Letters.

The fossil is part of the Royal Ontario Museum's vertebrate fossil collection.

Initially the skull and tail had been freed from the surrounding rock, but the body was still encased in 35,000 pounds of sandstone. After years of work, the body was revealed to have preserved most of the skin and bony armor across the entire back and flanks, giving a remarkable view of what the dinosaur looked like in life.

Zuul's body was covered in bony plates of different shapes and sizes, and the ones along its sides were particularly large and spiky.

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The scientists noticed that a number of spikes near the hips on both sides of the body were missing their tips.

The pattern of these injuries was more consistent with being the result of some form of ritualised combat, or jousting with their tail clubs, and probably wasn't caused by an attacking predator like a tyrannosaur because of where they were located on the body.

Zuul's tail was about 10 feet long, with sharp spikes running along its sides. The back half of the tail was stiff and the tip was encased in huge bony blobs, creating a formidable sledgehammer-like weapon.

Zuul crurivastator means "Zuul, the destroyer of shins," a nod to the idea that tail clubs were used to smash the legs of bipedal tyrannosaurs.

Years ago, Arbour had put forward the idea that ankylosaurs might have clubbed each other in the flanks, and that broken and healed ribs might provide evidence to support this idea.

But ankylosaur skeletons are extremely rare, making it hard to test this hypothesis.

The completely preserved back and tail of Zuul, including skin, allowed for an unusual glimpse into the lives of these incredible armored dinosaurs.

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