The abrasion adds to the evidence that the three-horned dinosaurs fought.
The largest known Triceratops has a hole in its bone frill, indicating that Big John, the dinosaur, fought with its contemporaries.
ZOIC LLC/F. BACCHIA
A gaping gash in a Triceratops named "Big John's" bony frill could be a battle scar from one of his contemporaries.
The frill that encircles Triceratops' head is a defining feature of its appearance. The perforations in the helmet are also iconic, at least to paleontologists. Researchers have argued numerous explanations for the holes, known as fenestrae, for over a century, ranging from battle scars to natural aging processes. Researchers write in Scientific Reports on April 7 that a microscopic inspection of Big John's partially healed lesion reveals it could be a traumatic injury from a fight with another Triceratops.
Flavio Bacchia, the director of Zoic LLC in Trieste, Italy, was reconstructing the skeleton of Big John, the largest known Triceratops to date, when he observed a keyhole-shaped fenestra on the right side of its frill in summer 2021. Bacchia then contacted Ruggero D'Anastasio, an Italian paleopathologist who studies injuries and diseases in ancient human and animal remains at the "G. D'Annunzio" University of Chieti-Pescara.
"I realized there was something weird when I saw the opening for the first time," D'Anastasio explains. The hole's uneven borders, in particular, seemed strange. It was unlike anything he'd ever seen before.
He cut a chunk of bone the size of a 9-volt battery from the bottom of the keyhole to study the fossilized tissues around the fenestra. Big John's remains were auctioned off for $7.7 million, making it the most valuable non-Tyrannosaurus rex dinosaur fossil ever.
D'Anastasio and his colleagues examined the bone under a scanning electron microscope and discovered evidence consistent with the production of new bone in animals. Blood arteries are generally used to support new bone formation, and the bone around the hole's edge was porous and studded with vascular canals. The bone exhibited a little trace of the arteries further out from the fenestra.
The researchers discovered that the irregularity of the hole borders noted by D'Anastasio was also present at the microscopic level. The border was speckled with microscopic dimples termed Howship lacunae, where bone cells destroyed the previous bone to be replaced with healthy bone in one of the initial steps of bone repair. Primary osteons, which emerge during new bone growth, were also observed by the researchers.
Furthermore, a chemical examination indicated elevated sulfur levels, indicating the presence of proteins involved in new bone production. Sulfur is present in small amounts in mature bones.
When looked at as a whole, it was evident that this fenestra was a partially healed wound. According to D'Anastasio, "the presence of mending bone is typical of the response to a traumatic incident."
Scientists can only speculate on what occurred so long ago. The location and shape of Big John's frill, however, imply that it was stabbed from behind by a Triceratops opponent, adding to evidence that Triceratops fought (SN: 1/27/09). According to the experts, an initial puncture was probably dragged downward to generate the keyhole shape.
"A pathology is a fantastic tool for understanding dinosaur behavior," says Filippo Bertozzi of the Royal Belgian Institute of Natural Sciences in Brussels, who was not involved in the research. Dinosaur behavior has long been a source of discussion, he says, but studies like these can shed light on the animals' way of existence.
He goes on to say that this particular wound is "not a Rosetta stone," because all fenestrae are unlikely to represent war injuries. "Fenestration remains a great enigma."
Why the bone remodeling shown in this Triceratops sample was more similar to healing seen in mammals than in other dinosaurs is also a mystery, according to D'Anastasio. Big John himself could be hiding even more truths.
D'Anastasio notes, "We published an aspect, a paleopathological case." "Big John's entire skeleton must be researched."
R. D’Anastasio et al. Histological and chemical diagnosis of a combat lesion in Triceratops. Scientific Reports. Published online April 7, 2022. DOI: 10.1038/s41598-022-08033-2.