Apatosaurus

The apatosaurus, commonly called brontosaurus, was a race of sauropod dinosaurs, surviving on prehistoric Earth. They are big, bulky, vegetarian and have incredibly long necks. They, like all other dinosaurs, were killed when the Cyber-Controller's ship crashed into the Earth. (DW: Earthshock) A few apatosaurs were briefly transported to the 1970s era London by Operation Golden Age. (DW: Invasion of the Dinosaurs) This was mentioned by the Doctor following his regeneration. (DW: Robot).

Behind the Scenes
In taxonomy, the name applied to the first discovered specimen has primacy. The names of subsequent finds misidentified as different genuses become synonyms. The first "brontosaurus" was a larger and more complete skeleton which lead this name to become more rooted in popular culture.