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How does a parrot's movable upper jaw help it handle food?

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Illustration of a rock parakeet (Pyrrhura rupicola) perched on a branch, showing green plumage with scalloped markings, a patch of red on the wing, and a dark beak. — Psittaciform Black-capped parakeet (*Pyrrhura rupicola*).

Parrots possess a highly kinetic (movable) upper jaw, a trait that is more highly developed in them than in any other bird. This mobility allows parrots to use their bills for manipulating objects and cracking hard nuts.1

The upper jaw is connected to the skull by a hinge and can move independently. When the quadrate bone swings forward, it pushes two series of bones in the roof of the mouth, causing the upper jaw to swing upward on its hinge. This mechanism, combined with the lower bill's chisel-shaped cutting edge and a highly manipulative tongue, enables the parrot to effectively hold and process food. For example, when eating seeds, the parrot uses its tongue and the filelike corrugations on the undersurface of the upper bill to hold the seed steady while the lower bill peels away the outer cover.1