Titanosaurus

Titanosaurus was an aquatic dinosaur-like monster that is one of the monsters under the control of Dr. Mafune.

Terror of Mechagodzilla
Titanosaurus was an amphibious dinosaur living in the Pacific Ocean. A scientist named Shinji Mafune had become obsessed with studying the brain patterns of marine animals and was cast out of the scientific community. Dr. Mafune was enraged and descended into madness and took mental control of Titanosaurus. He attacked a submarine ship investigating the remains of Mechagodzilla and rebuilt the giant robot. The peaceful Titanosaurus became vicious and aggressive, and teamed up with Mechagodzilla to wreak havoc.

Godzilla arrives in Tokyo to fight Titanosaurus, believing he can defeat the aquatic titan. However, Titanosaurus proved to be a powerful opponent and Godzilla was at a disadvantage. The INTERPOL Agency discovered that Titanosaurus' weakness was supersonic waves. Katsura committed suicide and Godzilla ripped off Mechagodzilla's head. After Mechagodzilla was destroyed, he turned on Titanosaurus. Titanosaurus was hit by Godzilla's atomic rays and the supersonic waves, and plummetted into the water. Whether Titanosaurus died or recovered is unknown.