Of course that image of a child's skull is real. Where do you think your adult teeth come from- do they magically appear in your mouth? No, they're formed in your jawline and then grow out into your gums as the space fills in with bone. Google "children's skull xray" and you'll clearly see the adult teeth forming.
I think we all know where our adult teeth come from. The tooth fairy surgically inserts them into our gums while we sleep, impatiently awaiting her cash (which is really just a diversionary tactic).