The Mechasaur who appears in Episode 6 of Getter Robo.
In the episode, Emperor Gore plans to isolate Tokyo, so he gets Mechasaur Ribo to cause destruction to the streets, highways, factories, and substations. Ribo causes the destruction by rolling up into a wheel and burrowing into the ground. When Michiru investigates one of the sites with her jet, Ribo launches one of his spikes and hits her jet's wing, causing her to spiral down. Afterwards, Ribo burrows into a power plant, making it explode.When Ryoma and Musashi investigate this, they find Ribo burrowing toward an abandoned factory. Using explosive barrels, Ryoma and Musashi draw the Mechasaur out and Ribo is revealed to them before it burrows further into the ground. Later, when Ryoma, Musashi, and Hayato find Ribo burrowing toward the city, Emperor Gore commands it to hide underground. When Ribo does so, Hayato combines the Getter Machines into Getter-2 and drills into the ground to search for it. They drill all the way down to find Ribo swimming in magma. Getter-2 tries to fight it, but can't work properly in a very low underground level. So Hayato drills back up to the surface with Ribo following. When they make it back to the surface, they hit Ribo with the Drill Arm. But this only causes the Mechasaur to roll back up into a wheel and does some damage to the city. So Ryoma changes into Getter-1, but his Getter Tomahawk and Getter Beam have no effect on Rigo's wheel form. Musashi then changes into Getter-3 and chases after Ribo when goes across the city. But the Mechasaur still continues destroying the city. During this time, Emperor Gore unleashes a Mechasaur submarine to the city. Ryoma then tells Musashi to throw Ribo into the ocean so it won't cause anymore damage. When Musashi manages to get Ribo, the three hear that a Mechasaur submarine is coming, so Musashi gets Getter-3 to throw Ribo into the ocean and into the path of the submarine. When Ribo and the submarine collide, they both explode and are destroyed for good.
Wheel Form: Ribo can roll up into a giant wheel form. When in Wheel Form, Ribo can spin become a buzz saw and to bouce off his opponent's attacks.
Burrowing: When in wheel form, Ribo can burrow into the ground.
Spikes: Ribo can launch the spikes on his back like missiles.