Researchers at the University of Chieti-Pescara have identified the cause of a unique, keyhole-shaped injury on the skull of “Big John,” the world’s largest documented Triceratops horridus. A study published in Scientific Reports concludes that the specimen, discovered in 2014 in the United States, survived a combat-related horn wound for at least six months before its death.
From South Dakota to Chieti
The journey of Big John began in the hills of South Dakota, where the specimen—measuring over 6 meters in length with a skull circumference of 2.5 meters—was unearthed. Following its recovery, the fossil was transported to the Zoic laboratories in Trieste in 2020 for restoration and skeletal assembly.
A Perforation Identified in Trieste
The investigation began after experts at the Zoic laboratory in Trieste noticed a distinct perforation on the dinosaur’s right squamosal bone while preparing the skeleton for display in 2020.
Chemical and electron microscope analyses confirmed the injury was not a post-mortem degradation or a birth defect. Instead, the team concluded it was a traumatic wound caused by the horn of a rival Triceratops that struck from behind, with the horn sliding into the bone structure. To reach this conclusion, Professor Ruggero D’Anastasio and his team, which included researchers from the University of Bologna, extracted a micro-sample from the edge of the hole for laboratory analysis in Chieti.
Evidence of Intraspecific Combat
The discovery provides scientific evidence for aggressive behavior among Triceratops populations, suggesting these animals engaged in violent combat to secure territory or mating rights. The tissue surrounding the perforation displayed clear signs of bone regeneration. Because the bone was still in the process of mineralizing at the time of the animal’s death, researchers inferred that Big John lived for at least six months following the duel.
Biological Parallels to Modern Mammals
Professor D’Anastasio highlighted that the histological formation of the Triceratops bone and its regeneration patterns are remarkably similar to those of modern mammals. The study suggests that the molecular and cellular processes—including protein matrix deposition and calcification—mirrored the way human bones repair fractures. This finding offers new insights into the biological history of the species, which lived approximately 66 million years ago. Comprehending how bone regenerated in a giant organism of the Cretaceous offers us extraordinary perspectives on general biology,
D’Anastasio explained.
NHK Produces Documentary on Big John Skeleton
The findings have become the focus of a documentary produced by Nippon Hōsō Kyōkai (NHK), Japan’s public broadcaster. Catenacci stated. The skeleton of Big John is currently housed at the Glazer Children’s Museum in Tampa, Florida.
Unanswered Questions
While the study confirms the nature of the injury and the survival timeline, the identity of the rival dinosaur remains unknown.
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