The ur-chicken, if I read this right is a red jungle fowl released in some misguided attempt to establish wild game bird populations in Georgia. It is the ancestor of the different varieties of chicken found throughout the world.But that would be like calling a chick that hatches from a chicken egg now something else. It's still a chicken. That ur-chicken was a chicken. That is why it laid a chicken egg.
Also how did you get that ur-chicken?
Would you expect a red jungle fowl to lay eggs that hatch into leghorns, Wyandottes or Jersey giants?
It finally occurs to me after all this time that you think the theory of evolution claims that species arise instantaneously from pre-existing species. The theory does not claim that nor does the evidence warrant such a conclusion. The theory does not say that birds hatched out of dinosaur eggs. The evidence does not say that either.
It is not an insult to point out that your understanding of evolution based on what you have said in this thread is flawed, inconsistent and in no way related to what is actually stated in science.