A close examination of over 400 Triceratops skulls suggests that the iconic dinosaurs used their powerful horns to clash with rivals over mates, territory, and dominance. In a new study, researchers looked carefully for traces of scrapes and healed fractures on the fossilized skulls, and say the pattern they found fits the theory that the three-horned herbivores were going head-to-head.
“The most likely culprit for all of the wounds on Triceratops frills was the horns of other Triceratops,” [lead researcher Andrew] Farke said. “Our findings provide some of the best evidence to date that Triceratops might have locked horns with each other, wrestling like modern antelope and deer” [Times Online].
The researchers compared the Triceratops skulls to those of another dinosaur called Centrosaurus, which also boasted three horns and a bony protective frill around its face. The two species were related, but Centrosaurus died out about 75 million years ago and had its largest horn on its snout, while Triceratops lasted until 65 million years ago and had more prominent horns over its eyes.
With such different horn patterns, the researchers assumed that if the dinosaurs were horn-butting with members of their own species the injuries of Triceratops and Centrosaurus should also be different from each other. But if they weren't poking and butting one another with those horns, the injuries should be relatively similar, perhaps due to random nicks from clumsily running into a tree or head butts from predators, Farke said [LiveScience].
As the researchers report in the journal PLoS ONE, the Triceratops skulls showed a pattern of old injuries in one specific part of the bony frill that would likely have been impacted if two individuals were banging their heads together, but the Centrosaurus showed no such pattern. While another faction of Triceratops researchers has argued that the horns were instead used as visual cues to attract mates, Farke notes that his research doesn't rule out that possibility.
"I like to use the analogy of a Swiss Army knife," Farke said. "They could have been used for a variety of purposes, such as defense, combat, and display." The ancestors of Triceratops had thin, enlarged frills and no oversized horns. This suggests the frill originally had a signaling function, say the authors, as well as a role in the attachment of jaw muscles. After big brow horns evolved, combat likely followed, spurring the frill to evolve to be thicker and tougher [Wired News].
However, not everyone is convinced by the new study, enticing as the image of battling Triceratops may be.
Attributing these skull lesions to combat “is very sexy” and is bound to attract a lot of attention “but it’s also very speculative,” says Mark Goodwin, a paleontologist.... “The evidence of different pathologies [in the two species] is not evidence of combat” in Triceratops, he adds, but the findings are “a first step” toward making a case. Detailed analyses of the bone in and around the lesions would help support the idea that Triceratops routinely engaged in combat, he suggests [Science News].
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