Rhedosaurus

The Rhedosaurus was a gigantic fictional dinosaur which was featured in the 1953 creature feature The Beast from 20,000 Fathoms.

Description
The Rhedosaurus was an enormous reptilian carnivore measuring thirty feet tall and one hundred feet long which resembled no dinosaur known today. It walked on all fours, although it was capable of rearing up on it's hind legs when the need arose, and had a row of sharp spines running down the length of its back. The creature had blood which carried a prehistoric plague which proved deadly to humans.

History
High up in the Arctic Circle, a nuclear weapon test thaws out the monstrous Rhedosaurus who had been slumbering in suspended animation. The beast proceeds to go on a killing spree, slaughtering all of the test personnel except one. Of course, when he relates this story to his superiors, they dismiss him as being delirious.

Eventually, once the creature has gone on a high-profile rampage down the U.S. East Coast, Thomas Nesbitt, the survivor from Rhedosaurus's initial attack, begins to convince those in authority of what he saw. Predicting that the beast is heading for the Hudson River - where Rhedosaurus fossils were first found - the monster makes land on Manhattan, where it's activities cost 180 their lives, injure a further 1,500, and cause $300 million of damage.

Once the U.S. military arrives on-scene, they hold Rhedosaurus back with an electrified barricade before using a bazooka to blow a hole in it's neck, forcing it back into the ocean. However, this has the unforeseen side-effect of releasing a virulent contagion held in the creature's blood onto the local population. As a result, the Army's plan to blow Rhedosaurus up is no longer viable.

A new scheme, to shoot the dinosaur with a radioactive isotope which will burn it from the inside out and eliminate the risk of further infection, is put into effect when Rhedosaurus comes ashore in an amusement park on Coney Island. An Army sharpshooter climbs the nearby rollercoaster and fires his radioactive rifle grenade into the gaping hole in Rhedosaurus, setting the unfortunate animal ablaze and ending its threat forever.