(An early sketch of the Tegu with a discarded color scheme.)Every good barbarian needs to have a run in with reptilian humanoids. Perseus had Medusa, Conan had Set, Kull had Thulsa Doom, He-Man had the Snake Men, and Adam had Lucifer. That doesn't even take into consideration these guys.
As you can see, at some point RiGBY would have to battle reptile people, the genre demands it.