Thanks to dramatic museum displays, many of us can imagine a Triceratops wielding its horns and sprawling neck frill to ward off a hungry Tyrannosaurus rex. But some scientists believe that Triceratopses used their deadly headgear against each other, too. Like dueling elk brandishing their antlers, Triceratopses may have interlocked their horns to woo mates or vanquish rivals.
While scientists have long speculated about such behavior, conclusive evidence of these clashes has proved elusive. But in a study published Thursday in the journal Scientific Reports, a team of Italian scientists describe what they believe is a gaping scar from one of these ancient battles on the neck frill of a high-profile Triceratops known as “Big John.”
Discovered by commercial fossil hunters at work on a South Dakota cliff side in 2014 and named after the rancher who owned the land, Big John received little fanfare until an Italian fossil-preparation firm purchased and restored the dinosaur’s remains in 2020. As the largest Triceratops specimen ever discovered (the skull alone measures more than five feet long), Big John was sold to an anonymous bidder last October for $7.7 million — the highest price ever for a non-Tyrannosaurus rex fossil.
In addition to its staggering size and price, the creature’s skull sports a large, crescent-shaped hole at the base of its neck frill. While many Triceratops skulls bear similar holes, few have been studied in depth according to Ruggero D’Anastasio, a paleopathologist at D’Annunzio University of Chieti–Pescara in Italy and an author of the study.
There has long been a debate about what causes these gaps in a Triceratops’s frill. Some believe they are scars of intraspecies tussles or close encounters with predators. Others think they may be signs of infectious diseases or potentially age-related breakdown of bone. In the case of Big John, the bone around the gap is caked in rough, plaque-like deposits, a sign that the area was once inflamed.
But to determine if the inflammation was caused by disease or traumatic injury, the researchers had to dig deeper. They examined bone tissue samples from around the gap in microscopic detail, looking for telltale signs of healing and bone remodeling.
By examining the samples under an electron microscope, the team observed that the bone closer to the opening was more porous and packed with blood vessels than the bone farther away, indicating that the gap was framed by newly formed bone. They also pinpointed tiny pits that commonly occur when bones are being reshaped by specialized cells, called osteoclasts.
All these signs point to a Triceratops on the mend. “The stages of healing of the bone are similar to those observed in mammals, including humans,” Dr. D’Anastasio said. “We are certainly facing a traumatic injury, which did not cause the death of the Triceratops.”
The researchers believe that the keyhole-shaped gap was punched into Big John’s frill by the horn of another Triceratops. The unique position of the wound led the researchers to hypothesize that the frill was punctured from the back.
However Big John was stabbed, the team estimates that the dinosaur survived for another six months based on the bone’s healing. When the plodding dinosaur died, some 66 million years ago, it was entombed in sediment in the Hell Creek Formation, a hotbed of fossils deposited toward the end of the dinosaur’s reign.
The Big John specimen is among a growing list of immense dinosaur fossils going for exorbitant amounts of money to private buyers. These staggering sums price out public museums and universities, creating barriers between exquisitely preserved specimens and paleontologists.
With Big John, for example, the bone tissue samples analyzed in the new study are stored in the collection of the University Museum of Chieti, but the whereabouts of the larger skeleton remain unknown. That hampers paleontologists’ ability to accurately vet the new findings, according to Denver Fowler, the curator of the Badlands Dinosaur Museum in North Dakota. “No one can actually go and see this pathological area for themselves,” he said. “Repeatability is the bottom line of science.”
These concerns have led the Society of Vertebrate Paleontology to discourage researchers from studying privately owned fossils.
Dr. Fowler thinks that if even a fraction of the money and attention spent on Big John were given to paleontologists it would help them discover, prepare and study more scientifically important Triceratops fossils.
“I expect that many museums have unprepared specimens of better quality and greater significance than Big John,” he said, “but a shortage of resources leave these specimens in their field jackets.”