Smoking-Gun Evidence of Man-Monkey Kindred: Episode II... Tails

This is not 'Hrun's law of atavisms', it is 'Hrun's tautology of atavisims' because it is true by definition and cannot be falsified. So you are stepping over the line with this one. No evolutionary biologist worth his salt would be caught using a tautology to support ToE.

Let's not forget about evolutionary constraints either.
Not only does the evolution of wings exact some fitness cost (check out the thread on Macroevolution toward the end), but its evolution may also be prevented by exisitng morphologies taht are valuable in their present form. Vertebrate wings are modifications of our 'arms' for flying and typically require loss of ability to oppose digits, among other things. Ready to give up arm wrestling and being able to type on a computer ?

Actually I think your law is 'evolving' along the right lines.
You are also gaining appreciation for the difficulties involved in the real process of stating a natural law. The same apply to formulating a good theory. The pivotal terms require very solid definitions for the theory to be functional. And I don't think your term 'fully developed' is far off the mark either. I would be hard put to improve on it.Actually, I kind of like your 'law'. If it were ever falsified, I guess it would constitute proof of Intelligent Design .