The Classic Skins Gamepass is a Gamepass available for purchase from the Dinosaur Simulator gamepass store (the "Store" tab next to the "About" tab; this applies to all Roblox games with gamepasses/gear). It's the most expensive gamepass, available for purchase at robux450.
This gamepass unlocks the classic (former) skins for dinosaurs such as Tyrannosaurus, Triceratops, and Brachiosaurus, which existed in the game before the major graphics update and switch to unioned models. By purchasing the model, 34+ classic skins are unlocked and available for use.
Because of the fact that classic skins were free and of a lower quality and playability than the base models of certain dinosaurs, ChickenEngineer didn't want new players selecting old, outdated models when playing as dinosaurs that had more advanced and fluid movements on the base models. Rather than remove the skins entirely, he opted to make the skins purchasable, putting them in a gamepass and offering the ability to play the classic skins to older players.
- There are some players that suffer a glitch that allows them to be able to select classic skins and gamepass skins without actually having owned or bought the gamepass, but they sadly cannot play as it when they spawn in.