Megapode chicks have an egg tooth while still in the egg .
Megapode chicks lose it before hatching , while kiwi chicks never develop one ; chicks of both families escape their eggs by kicking their way out .
Megapode chicks have an egg tooth while still in the egg but lose it before hatching , while kiwi chicks never develop one ; chicks of both families escape their eggs by kicking their way out .