Ceratopsians are a group of herbivorous dinosaurs known for their distinctive frills and horns. They lived during the late Cretaceous period, around 75 to 100 million years ago. Some well-known examples include Triceratops and Styracosaurus. These dinosaurs were primarily found in what is now North America and parts of Asia. Ceratopsians varied in size and shape, with some being small and others as large as a car. They had strong beaks for cropping plants and were likely social animals, often found in groups. Their unique features may have been used for defense, display, or species recognition.