Birds originally did have teeth. Beaks are thought to have replaced teeth because they serve the same purpose but are much lighter, and more importantly because they develop faster than teeth. Birds considerably predate grasses (which are what grains are).
I note that birds, which evolved eating grains, don’t have teeth
Birds originally did have teeth. Beaks are thought to have replaced teeth because they serve the same purpose but are much lighter, and more importantly because they develop faster than teeth. Birds considerably predate grasses (which are what grains are).