Besides the beak, what other organ did *Gastornis* rely on entirely for food processing, given its lack of teeth?

Answer

The gizzard

As an avian species lacking true teeth, *Gastornis* depended on its beak to ingest material, which was then processed internally using the gizzard.

Besides the beak, what other organ did *Gastornis* rely on entirely for food processing, given its lack of teeth?
birdextinctionfossilbiteGastornis