Humungousaur first appears at the end of "Pilot - Part 1" to take down an ambush by General John Briggs' military unit. Humungousaur is initially heavily implied to be there and he hides inside a cloud of smoke, silently picking apart soldiers before unleashing himself on the full unit.
Humungousaur is eventually overpowered by helicopters that launch a gas that incapacitates him. Will Harangue comes in with a large crew to do a report backed by Humungousaur's unconscious body. Humungousaur is lifted by Briggs' "chain-choppers" and brought to Briggs' father's base in the family name.
Humungousaur's appearance in "Pilot - Part 2" is simply a continuation of his previous one - his unconscious body is reported on, carried to Fort Briggs, woken up, and drained of energy by a blast of amphetamines Briggs uses to drain the Ultimatrix to attempt to experiment on it. Ben reverts to human form.
Humungousaur reappears in "Authorities" to take down a large group of drug dealers at the central headquarters of their company, FumeX. He is overpowered by the ignition of Demon's Blood, the weaponized chemical the dealers were smuggling under orders from Ssserpent, and goes ultimate to take them down and destroy the facility.
When Ben activates the Ultimatrix, glowing green veins crawl up his arms and legs. His muscles begin to bulge, and his bones increase in size. He bends down, clutching his fists, as his skin gets harder and his spine begins to contract and scales grow along his back. His skin now has cracks and scales on it, and his face elongates as his teeth become sharp and his mouth enlarges. His eyebrows gain a jagged, rocky shape as they enlarge. His eyes become larger and go hollow, before they begin to glow green and appear reptile-like as he grows a jagged tail, and the veins on his feet enlarge them and harden his toenails into jagged, clumped dinosaur-like feet. He spreads out his arms in fists and roars as his chest bulges and glows with energy until he stands up straight and the transformation is complete.
Humungousaur's appearance is very similar to that of Alien Force and Ultimate Alien, except it is far more realistic. His skin has a very rocky texture, but contains cracks and scales all over the darker areas. His chest contains scales along the side areas of his muscles, and they increase in occupation down to his knees. His head looks very similar to the Tyrannosaurus Rex from Jurassic Park, yet maintaining a humanoid shape. His back is covered in large scales, and there are very defined and jagged bumps along his spine. His tail is also very jagged, but is more scaly than the rest of his body to give it a more flexible appearance. His feet are very rocky and clumped, with large, cracked toenails and scales along his calf and the balls of his feet. His eyes glow green and have a very reptile-like appearance. The areas around his eyes and shoulders are darker than the rest of his body. His teeth are very spiked.
Behavior and Abilities
Humungousaur behaves more like a dinosaur than a human. He roars frequently, and rarely talks. In order to be realistic, Humungousaur's movement is slower than his other forms in order to give the character a sense of weight. The ground cracks when he runs, and his tail moves very lizard-like. Humungousaur's abilities remain the same. He has remarkable strength and is able to lift cars and trucks with ease. His strong body makes him resistant to strong force, though he can be frequently overpowered by extreme power and force. He also has the ability to expose spikes from the large scales in his body while he increases in size and strength. He gains large, spiked scales along his back, wrists, and tail. He can cause a significant amount of property damage even during movement. The ground cracks when he runs fast, and when he performs a powerful slam attack, he creates craters in the ground as debris flies everywhere. His personality is very aggressive, and he is often Ben's use of intimidation to his enemies.
Ultimate Humungousaur is Humungousaur's evolved form.
Ultimate Humungousaur is first used in "Authorities" during Humungousaur's reapperance. At the headquarters of FumeX, the main company most of Ssserpent's drug dealers were from, Humungosuaur is overpowered by ignited Demon's Blood, aka CRO-117, the corrosive chemical being smuggled around. Ultimate Humungousaur is able to withstand the attacks and responds to the dealers' use of firearms with a missile blast - he then proceeds to destroy the rest of the facility and leave an empty hangar, in which Ssserpent is interrogated in a side room.
Humungousaur starts to evolve by his veins glowing green.
His skin toughens and his blood flow intensifies, darkening parts of his skin before it recolors green. Parts of his muscles and bones bulge and turn jagged. His knuckles spew small "fountains" of smoke that become balls of fire that hover over his fists before metal caps cover them and bind themselves around a rotary bone that forms inside his wrist.
Humungousaur's back splits open and veins crawl out, forming an oval shape before metal plates form and join together into a large shell, from which spikes protrude in a mechanical fashion. Plates from the top his shell "unfold" and extend over to his head and form a spiked helmet. His teeth sharpen and his chest bulges as parts of it become reinforced with armor. The green veins lining his body join at the center and the Ultimatrix symbol extends four spikes.
Ultimate Humungousaur's appearance, while deriving from Humungousaur's more dinosaur-based anatomy in the show, remains largely unchanged in design.
His skin is a more faded green and is tougher, almost rocky. It has a lot of scales and cracks, and resembles a more greenish version of the skin of a Kaiju from the film Pacific Rim. His armor is rusted and coated with dust.