Of Gondwanan origin, tinamous are related to the ratites. Although the fossil record in South America is poor, the known tinamiform fossil record goes back 10 million years. Together with the ratites, they make up Palaeognathae ("old jaws"), while all other living birds are members of Neognathae ("new jaws"). Unlike the other palaeognaths, tinamous do have a keeled sternum. Like the other palaeognaths, they also have a distinctive palate (thin bony plate at top of mouth).