The Stegway is based on a Triceratops. They have some design features similar to the Moto Bugs, having two black and gray wheels on their undercarriage and a small engine on their rear. They also have a red body with a low-set exhaust on the rear resembling a tail, a yellow edges surrounding their undercarriage, and stubby two-clawed hands. On their face they have a sharp gray upper lip, a gray horn on the nose, black eyes, gray bony frill and two backward-turned gray horns.
Originally, Stegos would have appeared in Hidden Palace Zone, but the Zone and all its Badniks were both cut from the original game. By using Debug Mode in the Hidden Palace Zone in the Nick Arcade and Simon Wai prototypes, the player could place glitched in-game sprites of the Stegos. Stegos here had an attack pattern similar to the Snails where they would ram into the player when seeing them.
In the 2013 mobile release of Sonic the Hedgehog 2 which restored Hidden Palace, the Stegways made their official appearance in said Zone. In gameplay, they patrol their area slowly, then stops for a moment to suddenly charge in a way similar to a RhinoBot when spotting the playable character.
In early design documents, the Stegway is called Triceretops, but is referred to as Stego in the prototype's source code. This is most likely a remnant of the Stegosaurus variation that was considered during development, and would have likely been renamed if it made the original cut.
The design document listing the Stegway enemy as "Triceretops".