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Triceratops tussle: 'Big John' skull shows signs of battle, scientists say

A study of the fossil, which has been a flashpoint in the world of paleontology, indicates that Triceratops' famous horns and frills were used in battle with each other.
The fossilized "Big John" triceratops skeleton
The fossilized "Big John" triceratops skeleton was found in South Dakota in 2014 and restored by the Italian company Zoic in 2020. There is controversy over its subsequent sale in 2021 for more than $7 million to a private owner.Zoic LLC, Trieste, Italy

The dinosaur known as Big John — one of the largest triceratops fossils ever found – died after fighting with another triceratops, resulting in a severe injury to its heavily armored neck frill that then became infected, according to new research.

The research sheds light on the behavior of the massive dinosaurs, which lived 66 million to 69 million years ago, suggesting that their deadly horns and massive armored neck frills may have been mainly for protecting them against attacks from other triceratops, rather than other dinosaurs. The findings indicate that fighting between adult triceratops was a regular occurrence, although just why they were fighting can only be speculated.

While the combat wound didn’t kill the enormous animal outright, there was evidence that it may have caused a bacterial infection, and Big John could have died from that several months later, according to paleontologist Ruggero D’Anastasio. “Yes, it is possible,” he said in an email, noting the bone surface around the gash shows signs of inflammation that could have been caused by an infection.

The research determined that the traumatic injury (seen here on the left) on a bone that formed part of the animal's neck frill was probably made by the horn of another triceratops.Zoic LLC, Trieste, Italy

D’Anastasio is an associate professor at the University of Chieti-Pescara in Italy and the lead author of the new study, published Thursday in the journal Scientific Reports. The study of Big John’s prominent injury — a large hole pierced right through thick bone — was carried out as the Triceratops horridus skeleton was being assembled from its fossilized parts by Zoic LLC of Trieste, Italy. Another author of the paper, Flavio Bacchia, is a director of the company.

Big John has the world record for the largest triceratops skull yet found — over 5 feet long — and was probably among the largest of its kind. Although triceratops were plant-eaters, they were also huge. It’s estimated an adult was around 30 feet long, and weighed more than 12 tons.

Much of that mass was in its gigantic head, which was studded with three large horns — two above the eyes and one on its nose — and protected by the bony frill around its neck.

Zoic specializes in fossil reconstructions, and the company purchased the Big John skeleton in 2020 from a commercial paleontologist who found it in South Dakota.

After publicity displays in Trieste and Paris, the restored skeleton was sold in October 2021 for more than $7 million — a record for a triceratops fossil — to a private owner who hasn’t been publicly identified.

Some feared scientific access to the skeleton would be restricted as a result. But D’Anastasio said the new owner has stated the triceratops skeleton will be made available for research, and samples of its fossilized tissues are now in the university’s museum.

The size and shape of the hole in Big John’s neck frill correspond perfectly with the horn of a triceratops of similar size. A “combat simulation” of triceratops fighting, performed using plaster casts of the horns, helped the scientists better understand the event, he said.

Examinations show the gash had started to heal when Big John died, perhaps six months later — and while there is no surviving evidence of any scars, the wound was probably covered with new skin, he said.

D’Anastasio won’t speculate on just why Big John was fighting another triceratops but he acknowledges that it may have been over mates, as many birds — the descendants of dinosaurs — do today.

Some scientists suggest the distinctive horns and neck frills of triceratops may have been mainly to protect them from other triceratops, rather than other types of dinosaurs that might have regarded them as food. 

That would mean that the horns and neck frills of triceratops were used “not only as a display, but also as a means of attack and defense” against other members of their species, D’Anastasio said.

Commercial paleontologist Walter Stein said the Big John skeleton was up to 45 percent complete and the skull was up to 75 percent complete when he found it on a ranch in South Dakota in 2014, while the rest of it had long rotted away. (The missing bones were replaced in the reconstruction with casts of bones from other triceratops skeletons.)

Big John" has the largest skull ever found of its species (Triceratops horridus) and the animal probably weighed as much as 12 tons when it was alive.
Big John" has the largest skull ever found of its species (Triceratops horridus) and the animal probably weighed as much as 12 tons when it was alive.Zoic LLC, Trieste, Italy

U.S law states that fossils found on federal land belong to the government, but fossils on private land belong to the landowner and can be legally bought and sold.

Although some scientists have objected to the fossil’s sale to a private owner, Stein had tried for years to find an American museum to buy it.

“Not a single museum in the USA had ever contacted myself, or the landowners, or even shown any interest in the skeleton,” until it was purchased by Zoic, he said.

Stein noted triceratops skeletons are one of the most commonly found dinosaur fossils in the western United States, with more than 330 skeletons and skulls known. His team is now working on three more, including one that is probably even larger than Big John.

Veterinary pathologist Julie Engiles, an associate professor at the University of Pennsylvania School of Veterinary Medicine who has worked on dinosaur bones but wasn’t involved in the latest study, called the research “elegant and thorough.”

Although only the fossilized bones of the animal remain after millions of years, the researchers found detailed evidence of how the gash in its neck frill was made during a “traumatic insult” and how it became inflamed as a result, she said in an email.

Tyler Lyson, the curator of vertebrate paleontology at the Denver Museum of Nature and Science, who also didn’t take part in the study, said fossilized skeletons like that of Big John helped to bring the ancient beasts back to life. 

But he was uneasy that the skeleton had been sold to a private collector, because the basic scientific tenets of testability and reproducibility can not be achieved unless a specimen is made available to scientists, he said.