Stegosaurus

The stegosaurus was a type of dinosaur, characterised by flat plates on its back and spikes on its tail. They were herbivores and existed during the Jurassic period. The Third Doctor encountered some during Operation Golden Age. (TV: Invasion of the Dinosaurs) They were approximately 3.2 meters long and 4.1 meters high. (TV: The Lost Boy) A stegosaurus was worth 500 points in the I-Spyder Book of Earth Creatures if spotted. (PROSE:The Last Dodo)

On an alternate Earth, stegosaurus was one of the creatures bought back from extinction by the Silurians and were allowed to roam free (PROSE: Blood Heat)

A zoo on an Earth-like planet exhibited a stegosaurus or a stegosaurus-like creature. (COMIC: The Didus Expedition)

The last stegosaurus was exhibited in the Museum of the Last Ones. (PROSE: The Last Dodo)