Titanosaurus

Titanosaurus (チタノザウルス Chitanozaurusu) is a giant aquatic dinosaur kaiju who first appeared in the 1975 Toho Godzilla film, Terror of Mechagodzilla. Originally a peaceful, sea-dwelling dinosaur, Titanosaurus was discovered by Japanese marine biologist Shinzo Mafune, who was undertaking experiments involving controlling sea life. When Mafune claimed to his colleagues that he had discovered Titanosaurus and had complete control over him, he was laughed out of the scientific community and began a fifteen year-long quest for vengeance upon the civilization that had mocked and shunned him. When approached by the Black Hole Planet 3 Aliens, Mafune offered Titanosaurus' services to them for their invasion of Earth, being promised a place in their new utopian world order along with his daughter. Titanosaurus was unleashed alongside the aliens' Mechagodzilla 2, and the two beasts began obliterating Tokyo before they were confronted by Godzilla. Titanosaurus and Mechagodzilla's combination proved formidable, but the intervention of INTERPOL allowed Godzilla to destroy Mechagodzilla and easily defeat Titanosaurus in single combat after he was weakened by a sonic wave oscillator. Though he hasn't been featured in any films since his debut, Titanosaurus has appeared in some licensed video games and comic books based on the Godzilla franchise.