pachycephalosaurs and ceratopsians
"While triceratopses are one of the most recognizable dinosaurs, they are far from the only ones with distinctive features on and around their heads. This colorful, informative volume discusses the marginocephalians, dinosaurs with fringed heads. Readers will learn about how these dinosaurs' frills and thick or domed heads helped them identify one another, eat, and survive. Timelines and classifications help readers distinguish between various species and provide a complete picture of how the marginocephalians lived"--Back cover.