Everybody knows birds have beak instead of teeth. Some researchers believe this is for being lighter and fly better. Other ones think that the development of the teeth in the embryonic phase, i.e. inside the egg, would make the incubation period longer, so that the risk of being eaten by other species would be higher.
Even so, some birds are born with a small tooth. No kidding! Some bird species are born with a tiny tooth at the point of the beak, on the outer side.
You might wonder, how a lonely, external tooth, could be useful? How could they cut or chew something with this tooth?
What is this tooth for?
Easy answer! With this tooth they are able to break the egg shell that once protected them. That’s why it is known as “egg tooth”.
The egg tooth will vanish after a few days, since it is no longer useful and would be an extra weight to fly.
Some species don’t develop this tooth, so they have to break the egg shell with the beak and claws.
You can read more about this issue on the internet