That birds carry the genetic potential for teeth does not imply that they evolved from reptiles or any other creature except other birds that may or may not have had teeth.
In fact the article demonstrates that rather than a mutation occurring that suddenly tells chickens how to grow teeth, the genetic potential for teeth has been there all along and can be stimulated just by introducing the right chemical signals.
All this shows is that most creatures have more built in adaptability and variation in their genetic potential than we would normally assume.
Never implied this. The question dealt with the evolution of the gizzard, fairly unrelated to the article.
All this shows is that most creatures have more built in adaptability and variation in their genetic potential than we would normally assume.
Exactly. Homeotic genes and heterochrony give further credence to this idea.