One of Sunshine's star pupils, Rex King is from the United States. His special attack is called the "Jurassic Hand" with which his hand becomes a dinosaur hand (which later became fossilized due to the Spinning Toe Hold plus the Texas Clover Hold wearinng out the skin). It should be noted that Mantaro (acting as the referee in Rex's match with Terry) counted the teeth of the Jurassic Hand as claws, and so not against all rules against biting your opponent (although he was actually blackmailed by Sunshine to bend the rules to Rex's advantage, so it may not actually be true). In truth, he is actually is a dinosaur and his "Jurassic Hand" is his real head and what appears to be his "head" is a fake (in the 4Kids dub, he doesn't care about his head, stating that to him it merely holds his brain (which can apparently be pushed into his torso without much damage) and that his Jurassic Hand is the head that Terry the Kid had to worry about). He and Check Mate fought Gorgeousman and Barbarian and tore Barbarian in half with his Jurassic hand. He fights Terry the Kid at the Kintestu Buffalo's Osaka Dome. He pummeled Terry the Kid with his brutal attacks, but Mantaro helped out Terry by telling chillingly bad jokes (coldness being a dinosaur's weakness), however he stopped this by apparently being able to wear the earplugs that Sunshine gave him, despite his lack of visible ears as Gazelleman pointed out. He bears a resemblance to Beast Wars' Megatron.