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Note that there is an actual dinosaur called Titanosaurus that bears no relation.
Likewise, Titanosaurus is a massive semi-aquatic dinosaur that resembles a Spinosaurus, with large sails on his back and a long, crocodile-like snout. Some official sources claim he is a descendant of Allosaurus. He can use his prehensile tail and powerful legs to deliver a nasty kangaroo kick, however. Gorosaurus is essentially a Kaiju-sized Tyrannosaurus with no special abilities.
Strangely, he's got a pair of mammalian-like ears, which has led some fans to consider him a synapsid instead. Although he's a fraction of Godzilla's size he's still much larger than any real dinosaur.
Baragon is a quadrupedal dinosaur that can burrow through the ground like a mole and breathe fire. In the MonsterVerse setting, he's stated to be an ancient superspecies hailing from the Permian period, meaning he isn't even a pterosaur at all, but something similar and far older predating the entire pterosaur order by millions of years!
Rodan is either a colossal and very fictional relative of the Pteranodon or another atomic mutation depending on the continuity, much like Godzilla. His head horns are similar to those of ceratopsians as well. Anguirus somewhat resembles an Ankylosaurus but far, far larger. Godzilla himself is sometimes described as a dinosaur called a "Godzillasaurus" that mutated and grew to massive size due to exposure to radiation in the 1950s, but other times, like in the original film and the MonsterVerse continuity, it's made clear that he was always that big. Godzilla: The films use this trope as a frequent explanation for its Kaiju, Hand-Waving their enormous size and apparently supernatural abilities by saying that they simply aren't on the fossil record and thus anything goes. It has the quadrupedal stance and long neck of a sauropod, sharp teeth and claws of a theropod, and crocodile-like scaly skin. The Giant Behemoth: The eponymous behemoth is called a Paleosaurus.
The Beast from 20,000 Fathoms: The Rhedosaurus is a massive carnivorous dinosaur that moves around on four legs and has no trouble hanging out at the bottom of the ocean.