The horns and frills of dinosaurs like Triceratops and Styracosaurus weren't for defending against predators, regulating body temperature, or even attaching fearsome battle helmets, according to a study published this week in Proceedings of the Royal Society B. Rather researchers found the defining features of ceratopsian dinosaurs were actually for attracting mates. "Individuals are advertising their quality or genetic make-up," researcher Andrew Knapp tells the BBC. "We see that in peacocks too, with their tail feathers." Business Insider reports there are over 70 species of ceratopsian dinosaurs, and their horns and frills vary widely. Researchers behind the recent study had set out to see if the purpose of the horns and frills was to let different species tell each other apart for mating purposes (previous research had ruled out temperature regulation and defense).
After looking at 350 different traits from 46 ceratopsian species, researchers concluded that wasn't the case. In modern animals, features for species to differentiate between each other are typically subtler and more evolutionary work goes into features used to attract members of the same species. The relatively speedy evolution of horns and frills was also another clue as to their purpose. "Modern computer models have suggested that sexual selection can promote rapid speciation, adaptation, and extinction," Knapp says in a press release. As for both male and female ceratopsian dinosaurs having horns and frills, Knapp says it could "tell us a lot about how these animals lived." For example, they may have been co-parents when it came to raising their young. (The Sahara Desert revealed the "Holy Grail" of dinosaur discoveries.)