|Species|| 1/2 Tetramand|
|Body||Four-armed humanoid dinosaur|
|Powers and Abilities|
|Abilities|| Enhanced strength|
|First Appearance||The Coming of the Al-Ternates|
Fourmungousaur is a transformation fusion between Four Arms and Humungousaur. He can only be accessed by a broken Simplicitrix or Richard 10,000's Biosimplicitrix.
Fourmungousaur has the body of Humungousaur with the features of Four Arms. His skin is two toned like Humungousaur's, but the darker tan is replaced by Four Arms' green. He has four Humungousaur arms with Four Arms' gloves on the hands. On his arms and head are Four Arms' spikes. He has Humungousaur's white belt with a red stripe, along with Four Arms' pants that go above the belt. His feet are Four Arms' with Humungousaur's toe nails. His head is shaped like Four Arms' with his facial features and Humungousaur's nose. On his knees are the bolts from Richard 10,000's pants. The Biosimplicitrix is located on his sash.
He has all the powers of Humungousaur and Four Arms.
He has all the weaknesses of Humungousaur and Four Arms.