Stegosaurus

The stegosaurus was a type of herbivorous dinosaur, which existed on Earth during the Jurassic period. (AUDIO: The Monstrous Menagerie) They were approximately 3.2 metres long and 4.1 metres high. (TV: The Lost Boy)

History
Around 150,000,000 BC, time travellers from the 63rd century accidentally opened up a temporal link with 1894 London. A stegosaurus used the link to visit that year, and was encountered by Jago and Litefoot. (AUDIO: The Monstrous Menagerie)

In the 20th century, the Third Doctor encountered some during Operation Golden Age. (TV: Invasion of the Dinosaurs)

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

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

Alternate universe
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)