Reznor

Reznors are a quartet of fire-breathing dinosaurs on spinning platforms in Super Mario World. According to the instruction manual, they were cursed by Bowser. They spit fireballs at the player, who must hit their platforms from the bottom to defeat them. After two Reznors are knocked off their platforms, the floor will break away, exposing the molten lava below. If the player does not defeat the rest of the Reznors promptly, they will have to jump onto one of the abandoned platforms and fight from there. It is, however, possible to defeat all four without doing so.

They are the bosses of the many fortresses scattered through the areas of Dinosaur Land; the Vanilla Fortress, the Forest Fortress, the Chocolate Fortress, and the Valley Fortress.

Super Mario Adventures
In Super Mario Adventures, several Reznors are shown to inhabit the basement of the Koopalings' Tower, attacking anyone who is dumped into the basement. These Reznor were apparently destroyed when, after attacking Princess Toadstool, Friendly Floyd, Mario, Luigi, Toad, and Yoshi, the Reznors ignited a bomb held by Princess Toadstool, blowing up the Koopalings' Tower.

Later in Super Mario Adventures, several Reznors, riding their spinning platforms, can be seen at Bowser's wedding to Princess Toadstool.