Birds can theoretically develop teeth
Seventy to eighty million years after their ancestors gave up teeth, birds still have the genetic makeup to develop these mandibles.
This is proven by studies by Matthew Harris from the Max Planck Institute for Developmental Biology in Tübingen on a special breeding line of chickens, which is referred to as the Talpid2 mutation. They carry a special genetic makeup that triggers tooth formation in the upper and lower jaws of embryonic chicks. These teeth are similar in their developmental position in the jaw to those of mammals, and their formation is triggered by the same molecular signals.
The mandibles actually forming in the embryo, however, differ structurally from those of mammals. Instead, clear parallels were found with the teeth of alligators, the closest living relatives of modern birds. So despite long ago splitting off from their common ancestor, birds can still develop teeth, even if this process can only be triggered artificially. The group of animals lost the ability back then, parallel to the development of their beak with its horny sheath.
