How many species do you really know about - not just the well-known ones but random weird ones as well? Find out what makes a dinosaur a dinosaur and what the environment was like when they roamed the Earth.

Dinosaur definitions. What is a dinosaur? ; Definitely dinosaurs ; Dino checklist -- Dinosaur detectives. Triceratops ; Family tree ; Triceratops relatives -- Dinosaur discoveries. When and where -- Ask an expert: What was the environment like when dinosaurs were around? -- Delve into a dinosaur. Anatomy of Triceratops ; The skeleton ; The body -- Dinosaur domains. Habitats and ecosystems -- New science: Inflatable nose balloons? -- Dodging dinosaurs. Evolutionary arms race ; The battle -- Fossil finder -- Quiz answers.