Modifiers matching tetrapod:

• poikilothermic,
• terrestrial,
• amphibious,
• herbivorous,
• aquatic,
• modern,

Simple categories matching amphibious:

• mammal,
• animal,
• inhabitant,
• tetrapod,
• creature,
• decapod,
• being,
• vertebrate,
• reptile,
• friend,