Final answer:
Birds lost the feature of teeth about 150 million years ago during the late Jurassic period.
Step-by-step explanation:
The feature of teeth was lost to birds about 150 million years ago during the late Jurassic period. Archaeopteryx, a fossil from this time, had teeth similar to dinosaurs but also had flight feathers like modern birds. The loss of teeth allowed birds to develop beaks, which are specialized structures for feeding.