Modifiers matching ratite:

• flightless,
• extinct,
• modern,
• large,

Simple categories matching extinct:

• vertebrate,
• animal,
• plant,
• herbivore,
• mammal,
• beast,
• creature,
• relative,
• giant,
• reptile,
• equid,
• dinosaur,
• fauna,
• predator,
• organism,
• ratite,
• archosaur,
• amniote,
• human,
• bird,