Triceratops Horns Used for Combat with Each Other

A research team from the Royal Tyrrell Museum of Palaeontology in Canada, the Raymond M. Alf Museum of Paleontology in the United States, and other institutions has announced that it is highly likely that the horns of the famous three-horned dinosaur, Triceratops, were used for fighting among themselves.

They found that the proportion of injuries to the front part of the frill of 53 Triceratops specimens was 10 times higher than that of Centrosaurus (another ceratopsian) from the same period.

They seem to conclude that "if they had fought to repel carnivorous dinosaurs such as Tyrannosaurus of the same period, both (Triceratops and Centrosaurus) would be expected to have injuries at the same rate. In reality, the injuries on Triceratops are overwhelmingly more numerous, so many of the frill injuries on Triceratops were likely caused by fighting among themselves."

However, the horns of modern moose are used for duels between individuals, but they also serve to display to the opposite sex.
They state that "even if it is statistically proven that the horns of ceratopsians were used for fighting among themselves," it does not "negate their role in defense against carnivorous dinosaurs or as a display to the opposite sex. Like the horns of moose, it is highly likely that they had multiple roles."