0 104 Mesozoic Dinosaurs TI 7/24/2003 0 In millions of years 0 0 BC 225 Triassic Period Triassic Period_enter__enter_ 0 0 BC 220 Ancestors of dinosaurs Thecondonts: ancestors of dinosaurs_enter__enter_ 0 0 BC 200 Small theropods Coelurosaurs: small theropods_enter__enter_ 0 0 BC 170 Jurassic Period Jurassic Period: 170-130 million B.C._enter__enter_ 0 0 BC 170 Stegosaurs Stegosaurs: plated dinosaurs. 170 million B.C._enter_ 0 0 BC 170 Sauropods Sauropods: giant dinosaurs 170 million B.C._enter__enter_ 0 0 BC 136 Theropods Theropods: carnivorous dinosaurs_enter__enter__enter_ 0 0 BC 136 Ankylosaurs Ankylosaurs: armored dinosaurs_enter__enter__enter__enter__enter_ 0 0 BC 130 Cretaceous Period Cretaceous Period_enter__enter__enter_ 0 0 BC 110 Ornithopods Ornithopods: duck-billed dinosaurs_enter__enter_ 0 0 BC 90 Ceratopsians Ceratopsians: horned dinosaurs_enter__enter_ 0 0 BC 70 Rocky Mountains begin to rise Rocky Mountains begin to rise_enter__enter_