Titanosaurus

Titanosaurus is a fictional kaiju (giant monster) featured in the 1975 Japanese tokusatsu film Terror of Mechagodzilla, the fifteenth Godzilla film to be produced by Toho.

An amphibious dinosaur found in the Pacific Ocean, the character appeared only once, as one of two antagonists in the film. Titanosaurus shares its name with a real dinosaur species, though they do not share much beyond nomenclature; the real Titanosaur was a peaceful, land-dwelling sauropod, while the one featured in Mechagodzilla is a frightening, intense creature who sports a fin along his back.

In Terror of Mechagodzilla, a mad scientist named Shinji Mafune (portrayed by Akihiko Hirata) becomes so obsessed with studying the brain patterns of marine life that he loses his academic credentials and is cast out from the scientific community. Quickly, descending into madness, Mafune is able to gain control of Titanosaurus, with the help of aliens from Black Hole Planet 3, after it attacks a submarine investigating the remains of the destroyed Mechagodzilla, from the previous film, Godzilla vs. Mechagodzilla. Dr. Mafune rebuilds Mechagodzilla, and with both monsters under control, begins his revenge on humanity. Both are ultimately defeated by Godzilla.

The Titanosaurus character has not appeared in any films since, aside from a brief flashback during the opening credits of 2004's Godzilla: Final Wars.