The ornithomimus was a type of theropod dinosaur. They were small dinosaurs, only coming up to a human's shoulder in height. As their name would suggest, they were rather ostrich-like in appearance, but with smooth skin, a long tail, short arms and a toothless mouth. They were mottled brown and grey in colour over most of their bodies, with dark orange stripes along their backs. They were omnivorous, feeding on fruits and insects. The ornithomimus lived during the Cretaceous period.
The ornithomimus was one of the species that the Silurians brought back from extinction after they took over in a parallel world. The Seventh Doctor, Ace and an alternate universe version of Jo Grant rode ornithomimuses into a herd of seismosaurus in order to escape from Silurian hunters. (PROSE: Blood Heat)