“Big John” the Triceratops was in bust-up with another trike

In the 1993 dino flick Jurassic Park, paleobotanist Dr Ellie Sattler separates from the group to care for a sick Triceratops. The creature is portrayed as a gentle giant, but as it turns out Triceratops could be aggressive and pugnacious, too.

In fact, palaeontologists have theorised for decades that Triceratops engaged in violent physical combat with one another, based on fossil evidence of traumatic skull injuries. Now, in a new study in Nature Scientific Reports, Italian scientists have unveiled further evidence that trikes lived “by the sword”, engaging in fierce battles and living to tell the tale.

“Big John” was a prodigiously large trike who lived near Hell Creek in what is now Montana, US, during the Upper Cretaceous, more than 66 million years ago. 

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Big John’s fossil bones. Credit: Zoic Limited Liability Company, Trieste, Italy.

His extraordinarily complete fossil skeleton, which sold to a private owner at auction last year for $10 million, was encased in mud when the ancient floodplain he died on periodically overflowed – and there he lay, undisturbed for tens of millions of years, until palaeontologists unearthed him in 2014.

According to this new analysis, Big John’s skull bone displays a keyhole-shaped opening known as a fenestra. The bone surface around this opening is irregular and overlaid with plaque-like deposits, which the authors believe could be a tell-tale sign of infection. Even more fascinating, the researchers analysed samples from the margin of the fenestra which showed that the bone tissue around the hole was porous, and peppered with lots of blood vessels, characteristic of newly formed bone. 

Taken together, these signs suggest that Big John sustained a traumatic injury to the skull – and lived to tell the tale. In fact, the injury had likely been healing for months at the time he breathed his last. 

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The squamosal bone of Big John showing the traumatic lesion. Credit: Zoic Limited Liability Company, Trieste, Italy.

“Considering the healing times of traumatic injuries in modern reptiles, along with the size of the traumatic injury and the amount of bone repair, it is likely that the death of Big John occurred at least six months after this traumatic event,” the authors write.

It’s rare in palaeontology that fossilised remains can tell us a story about how an animal behaved in life, but based on the size and location of the injury, the researchers believe it could only have been made by another triceratops, giving credence to the combat theory. 

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The restored skull of Big John (Triceratops horridus) in lateral-posterior view. Credit: Zoic Limited Liability Company, Trieste, Italy.

Even more tantalising, the study offers clues about how dinosaur bodies healed from trauma.

“Although the physiological and cellular mechanisms underlying the healing process in dinosaurs are still largely unknown, it would appear to be similar to those described in humans and mammals,” the authors write.

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