9780253353580_lrgH.D. Sues about Ryan, M.J., B.J. Chinnery-Allgeier & D.A. Eberth. Eds. 2010. New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. – Bloomington, Indiana University Press

The Ceratopsia or horned dinosaurs are a very distinctive group of ornithischian dinosaurs. All have a narrow beak, and most have bony collars or frills extending from the back of the skull. The earliest forms were still rather small and bipedal. Later taxa attained large head and body size and became quadrupedal; they are often considered the dinosaurian analogue of a rhinoceros. Most of these derived forms also sport prominent nasal and/or supraorbital horns. One of the geologically youngest ceratopsians, Triceratops, ranks among the most widely known dinosaurs, rivaling its likely predator, Tyrannosaurus rex, in popular recognition.
Despite their appeal, ceratopsians have been the subject of only a few comprehensive studies. […]