Watch any black-and-white movie about dinosaurs, and you're likely to see a Triceratops jabbing a Tyrannosaurus rex with its horns. Over the years, paleontologists have backtracked on the idea that these horns were weapons, however, with some arguing that they may have been merely for show. But a new study suggests that those early filmmakers had it right: Triceratops may have locked horns after all.
Triceratops looks like it was built for battle. Two long horns jut out from above its eyebrows, and a third protrudes from the tip of the nose. Then there's the shieldlike frill that sweeps back and fans out from its face. But, like peacock feathers, the horns might have been signs to advertise health or fertility.
In an effort to settle the debate, paleontologist Andrew Farke of the Raymond M. Alf Museum of Paleontology in Claremont, California, and his colleagues examined 400 skull bones of Triceratops and a fellow, three-horned predecessor called Centrosaurus. Centrosaurus differs from Triceratops in that its nose horn is much larger than the other two horns, much like a rhinoceros. To Farke, that suggested that Centrosaurus had an alternative style of combat, possibly a body attack versus a head butt. And indeed, his team found that Triceratops skulls sported 10 times more fractures and lesions than the Centrosaur skulls. The lesions were concentrated on the side of the frill, probably because its large area made it more vulnerable during battle.
Farke doesn't rule out that the horns were also used for display purposes. "They're kind of like a Swiss army knife," he says. "They could use them however they wanted."
Still, paleontologist Jack Horner of the Museum of the Rockies in Bozeman, Montana, is not sold on the horns-as-weapons theory. "They seem to make the case that since there is trauma, it has to be due to combat," he says, "whereas, I would say if it's trauma caused by combat, why isn't it more prevalent and more traumatic? Why aren't there more actual punctures if indeed these animals are poking each other with sharp horns?"
Farke is sticking to his interpretation. His team next plans to examine more Triceratops skulls and even T. rex ribs to see if they show signs of battle damage--perhaps being cracked by a horn.