New find suggests ankylosaur’s tail clubs were for bashing each other - Ars Technica

Enlarge / The process clubs of ankylosaur taxon look to person been utilized to bash each different alternatively than predators.

Henry Sharpe

New probe indicates that the process clubs connected immense armored dinosaurs known arsenic ankylosaurs whitethorn person evolved to whack each different alternatively than deter bare predators. This is simply a implicit displacement from what was antecedently believed.

Prior to the insubstantial published contiguous successful Biology Letters, astir scientists looked upon the dinosaur’s process club, a important bony protrusion comprised of 2 oval-shaped knobs, chiefly arsenic a defence against predation. The squad down the caller insubstantial argues that this is not needfully the case. To marque their case, they absorption connected years of ankylosaur research, investigation of the fossil record, and information from an exceptionally well-preserved specimen named Zuul crurivastator.

Zuul’s name, successful fact, embraces that erstwhile idea. While "Zuul" references the carnal successful the archetypal Ghostbusters, the 2 Latin words that marque up its taxon sanction are crus (shin oregon shank) and vastator (destroyer). Hence, the destroyer of shins: a nonstop notation to wherever the dinosaur’s nine whitethorn person struck approaching tyrannosaurs oregon different theropods.

But that sanction was fixed erstwhile lone its skull and process had been excavated from the stone wherever the fossil was encased. After years of skilled enactment by the fossil preparators astatine the Royal Ontario Museum, Zuul’s full backmost and flanks are exposed, offering important clues arsenic to what its process nine mightiness target.

Target identification

Lead writer Dr. Victoria Arbour is presently the Curator of Paleontology astatine the Royal British Columbia Museum, but she’s a erstwhile NSERC postdoctoral chap astatine the Royal Ontario Museum successful Toronto. That’s been Zuul’s location since 2016, 2 years aft its archetypal find successful Montana. She’s spent years studying ankylosaurs, a benignant of dinosaur that look successful the fossil grounds from the Jurassic done the extremity of the Cretaceous. Some taxon of ankylosaurs person process clubs, portion others, known arsenic nodosaurs, bash not. That quality raises immoderate questions astir what these structures were utilized for.

“I deliberation a earthy follow-up question from, ‘Could they usage their process clubs arsenic a weapon?’ is ‘Who are they utilizing that limb against?’” Arbour explained. “And truthful that’s wherever I truly started reasoning astir this.

Back successful 2009, she authored a paper that suggested ankylosaurs mightiness usage their process clubs for intraspecific combat—fights with different ankylosaurs. That enactment focused connected the imaginable interaction of process clubs erstwhile utilized arsenic a weapon, particularly arsenic the clubs travel successful assorted shapes and sizes, and successful immoderate species, weren’t adjacent contiguous until the carnal matured. Measuring disposable fossil process clubs and estimating the unit of the blows they could produce, she recovered that smaller clubs (approximately 200 millimeters oregon fractional a foot) were excessively tiny to beryllium utilized arsenic a defence against predators.

Zuul crurivastator, the shin-basher.

Royal Ontario Museum

She recommended further research, noting that if ankylosaurs were utilizing them for intraspecific combat, 1 mightiness expect to spot injuries on big flanks, arsenic an ankylosaur process tin lone plaything truthful far.

It’s 1 happening to person an thought astir an extinct animal, but it’s different to person evidence. Ankylosaur fossils are uncommon successful general; dinosaurs with preservation of the tissues that would person been damaged successful these fights are overmuch rarer. So it’s astounding that Arbour could trial her ideas acknowledgment to an carnal with its full back—most of its tegument and all—intact.

“I enactment retired this thought that we would expect to spot harm connected the flanks, conscionable based connected however they mightiness enactment up against each other,” Arbour told Ars. “And past a decennary and a spot later, we get this astonishing skeleton of Zuul with harm close wherever we thought we mightiness spot it. And that was beauteous exciting!”

Damage assessment

Zuul’s backmost and flanks are covered successful assorted spikes and bony structures called osteoderms. Just arsenic Arbour predicted, determination is grounds of breached and injured osteoderms connected some sides of the flanks, immoderate of which look to person healed.

“We besides did immoderate benignant of basal statistic to amusement that the injuries are not randomly distributed connected the body,” she continued. “They truly are conscionable restricted to the sides successful the areas astir the hips. That can’t beryllium explained conscionable by random chance. It seems much apt that it’s [the effect of] repeated behavior.”

A damaged but partially healed spike connected the broadside of Zuul.

Royal Ontario Museum

There are lone a fistful of well-preserved ankylosaurs, including astatine slightest 1 of a nodosaur named Borealopelta astatine the Royal Tyrrell Museum. The authors enactment that determination aren’t immoderate comparable injuries connected known nodosaurs, a germane point. As mentioned previously, nodosaurs don’t person process clubs and frankincense wouldn’t person been capable to usage them against each other.

Equally important, the harm isn’t accompanied by grounds of predation. No wound marks, puncture wounds, oregon bony scratches are recovered anyplace connected Zuul’s body.