Ultimate Humungousaur had dark green skin, with a dark blue shell on his back, surrounded by silver spikes and his chest was of the same color. The evolved Ultimatrix symbol was on his chest. Or, he has tan skin instead of green, his shell and chest have a blue metallic color, and he is surrounded by bone spikes, which are on his face as well. His skin is torn apart on some spots, revealing metallic parts underneath.
In John Smith 10, he has his UAF appearance, until Omniverse, where he gains his Omniverse appearance.
When used by the Intellectuary, the shell on his head extends over his right eye.