New discovery suggests Ankylosaurus tail clubs were used to smack each other

New research suggests that the tail clubs of giant armored dinosaurs known as ankylosaurs may have evolved to smack each other rather than scare away hungry predators. This is a complete change from what was previously believed.

Prior to today’s Biology Letters article, most scientists thought of the dinosaur’s tail club, a sizable bony prominence composed of two oval knobs, primarily as a defense against predators. The team behind the new document argues that’s not necessarily the case. To make their point, they focus on years of ankylosaur research, analysis of the fossil record, and data from an exceptionally well-preserved specimen called The Blood-Chilling Roar.

The name Zuul actually encompasses this earlier idea. While “zuul” refers to the creature in the original Ghostbusters, the two Latin words that make up the species name are raw (shin or hock) and responder (destroyer). Hence the shin destroyer: a direct indication of where the dinosaur mace might have struck the approaching tyrannosaurs or other theropods.

But that name was given when only its skull and tail had been extracted from the rock in which the fossil was encased. After years of expert work by fossil taxidermists at the Royal Ontario Museum, Zuul’s entire back and sides have been exposed, providing important clues as to where his tail club might be aiming.

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The lead author, Dr. Victoria Arbour, is currently curator of paleontology at the Royal British Columbia Museum but is a former NSERC postdoctoral fellow at the Royal Ontario Museum in Toronto. It has been Zuul’s home since 2016, two years after he was first discovered in Montana. She spent years studying ankylosaurs, a species of dinosaur found in the fossil record from the Jurassic to the late Cretaceous. Some species of ankylosaurs have tail clubs, while others known as nodosaurs do not. This difference raises questions about the use of these structures.

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“I think a natural follow-up to, ‘Could you use your cue sticks as a weapon?’ is, ‘Who are they using this gun on?'” Arbor explained. “And that’s when I really started thinking about it.

In 2009, she authored a paper in which she suggested that ankylosaurs could use their tail clubs for intraspecific fights – fights with other ankylosaurs. This work has focused on the possible effects of tail clubs when used as a weapon, particularly since clubs come in many different shapes and sizes and, until recently, in some species were not even present until the animal reached adulthood. By measuring the fossil-tailed clubs available and estimating the power of the blows they could produce, she discovered that the smaller clubs (about 200 millimeters or half a foot) were too small to be used as a defense against predators.

They recommended further research, noting that when ankylosaurs used them for intraspecific fighting, one would expect to see wounds along the flanks of adults, since an ankylosaur tail can only swing so far. p>

It’s one thing to have an idea about an extinct animal, but it’s another thing to have evidence. Ankylosaurus fossils are generally rare; Dinosaurs with tissue preservation that would have been damaged in these battles are much rarer. So it’s amazing that Arbor was able to test his ideas on an animal with the entire back – most of the skin and all – intact.

“I had the idea that we would expect damage on the flanks just based on how they might face each other,” Arbor told Ars. “And then, a decade and a little later, we get this amazing Zuul skeleton with damage.” , where we thought we could see it. And that was pretty exciting!