Horns and Frills
Around 84 million years ago, some ceratopsians evolved long horns and big frills. At the same time, they also started becoming much larger—some measuring over 30 feet from beak to tail! Some had nasal horns only. Others had brow horns. Horns could be straight or curved, and frills could have knobs or spikes on them. Scientists are not exactly sure the purpose of these big horns and frills, but they have some ideas.
While heavy frills could have served as protection from the attacks of predators like T. rex, many ceratopsian frills were too thin and lightly constructed for this. Some ceratopsians had smaller frills, frills with large openings, or frills that had many small holes. These would have been no defense against the bite of a hungry predator.
Ceratopsians might have used their large horns to frighten off other ceratopsians. If the sight of the horns and frills didn’t work, then the ceratopsians might have used them to fight each other.
Ceratopsians probably had frills and horns to find mates and recognize members of their own species. The biggest horns and fanciest frills could have helped males attract females, similar to the way that male peacocks use their brilliant tails to display for females.