Stegosaurus

The Stegosaurus was a type of dinosaur, characterised by their flat plates on their back and spikes on their tail. They were herbivores and existed during the Jurassic period. The Third Doctor encountered some during Operation Golden Age. (DW: Invasion of the Dinosaurs)

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