5 - 6 feet tall
An Evolvosaurus is a shapeshifting monster which can swap forms with other creatures through touch.
An Evolvosaurus took the place of a boy at a funfair.
When Jake, Hayley and Kirby arrive and Jake identifies the boy as the monster, the Evolvosaurus tries to escape, but is knocked out and returned to its true form by a blast from Jake. It is then placed in Troop captivity and scheduled to be returned to the Monster Dimension.
However, the Evolvosaurus is able to successfully trick Hayley into entering its containment cell and take her place by hiding out of sight and then ambushing her and taking her place. However, the Evolvosaurus finds posing as Hayley very difficult due to the challenges of Hayley's everyday life.
The Evolvosaurus is eventually uncovered during a dance contest by its poor mimicry of Hayley's dancing skills, and is defeated and recaptured by Jake and Kirby
It is then taken to a rural site for returning monsters to their world, where, having learned how much harder Hayley's life is, willingly re-trades places with her and flees through a portal back into the Monster World.
The Evolvosaurus appears to be a brownish-colored humanoid with several body folds, two rows of three upward-curved dorsal fins on its back, three long fingers, two crimson eyes, a mouthless face, broad shoulders, and a round head with no neck.
In their true form, Evolvosaurus are shown to communicate in shrill chirping sounds.
An Evolvosaurus possesses high intelligence, and can switch forms with the next organism it touches.
When an Evolvosaurus takes a victim's form, it does not take their skills and abilities, making it easy to spot as a fake.