Triceratops
From TARDIS Index File, the free Doctor Who reference.
The Triceratops were a type of herbivous dinosaurs living on prehistoric Earth.
They have two large horns at the top of their heads and one small one near their nose. They weighed over a ton and could be very dangerous in a fight. They had a frill made of solid bone above their heads and ate with beaks. They, like all other dinosaurs, were wiped out when the Cyber-Controller's ship crashed into Earth. (DW: Earthshock)
The Doctor encountered a few that had been transported to the 1970s. (DW: Invasion of the Dinosaurs)
