The Godzillasaurus is different from other theropods because its posture is more upright like a human, and it drags its tail on the ground, much like older theropod reconstructions. At 12 meters in height, it is much larger than any other theropod species, probably due to its erect posture. It has a smaller head than a real theropod, and has a double-row of teeth, much like a shark. The Godzillasaurus species is also different from other theropod dinosaurs due to the fact that it contains a second, or "sacral", brain located in its hip to control lower body functions, like how the Stegosaurus might have had a second brain.
As is shown in Godzilla vs. MechaGodzilla 2, Godzillasauruses seem to be telepathic, as Baby Godzilla can contact his father. However, it is unknown if an unmutated Godzillasaurus would have this ability.
The Godzillasaurus lived out in Lagos Island in Godzilla vs. King Ghidorah, and was attacked by soldiers during World War II. This was observed by Futurians that had traveled back in time to remove Godzilla from history. They transported the wounded Godzillasaurus to the Bering Sea, thinking it would die. However, the Godzillasaurus was mutated by a nuclear submarine crash without them knowing.
- Main article: Godzilla Junior.
Another Godzillasaurus, Baby Godzilla, is found in Rodan's nest in Godzilla vs. MechaGodzilla 2. This one seems to have been affected by nuclear radiation as well, considering the fact that when he was Little Godzilla in Godzilla vs. SpaceGodzilla, he was bigger than the seemingly adult Godzillasaurus.
- Main article: Godzilla.
The back side of the box of Jakks Pacific's Giant Godzilla figure states Godzilla was an amphibious reptile evolved while Earth had ten times more radiation. In Godzilla: Awakening, it's revealed that the species originated in the Permian Age and survived the countless mass extinctions afterwards.
Despite its relatively small size, the Godzillasaurus that would eventually become Godzilla displayed a high amount of strength and endurance. Small arm's fire and even rocket launchers were unable to damage him, and only barrages from several battleships were the only things strong enough to draw blood and weaken it.
- Main article: Gallery:Godzillasaurus.
In Other Languages
- Spanish: Godzillasaurio
- Russian: Годзиллазавр
- Portuguese: Godzillassauro
- In "Godzilla: A History," a book about Godzilla made by Kenichiro Terasawa, the main character of Godzilla vs. King Ghidorah, one of Terasawa's theories about how Godzilla came to be was that he was mutated from a whale, or kujira, that had Godzilla's dorsal plates.
- An actual species of dinosaur was named the Gojirasaurus, in homage to Godzilla himself. However, this "Godzillasaurus" bears only a slight resemblance to its movie counterpart, and is a dubious genus - which means that it may be a different type of dinosaur altogether.
- It is possible that Godzillasaurus is related to Therzinosaurus as it may be also a plant eater despite having sharp teeth (this is proven as of Baby Godzilla's diet). It is also possible that it is not a theropod at all and is instead a species of neo-prosauropod. This would explain its upright stance (some semi-bipedal prosauropods stood like this), its small head, its sacral brain and that it seems to be at least partially herbivorous.
- However, in deleted scenes from Gojira, Godzilla vs. Biollante and Godzilla vs. Destoroyah, Godzilla and Godzilla Junior were seen eating meat (cows, the unmade monster Deutalios, and whales, respectively). This could be an indication that the diet of Godzillasaurus is omnivorous or even completely carnivorous, though this could be because of them being mutated and thus needing an appropriate change in their diets.
- In Legendary Pictures' Godzilla, Godzillas were giant amphibious reptiles that evolved when Earth had ten times more radiation than it has today.