Which Came First, the Chicken or the Egg?

When I thought about this question it was really hard to figure out because the way it's phrased it's essentially either a chicken just pops into existence, or an egg just pops into existence, without any parent animals involved. I thought about this and decided that because of evolution it would be the egg that came first.

The reason I think this is because two birds that were a tiny bit like chickens would probably have had an egg, and then when that bird was all grown up it was more like a chicken. Then it had an egg, which was even more like a chicken, and so on. So at this point, basically, two birds would make the first chicken egg. The parents characteristics were quite close to a chicken but not quite a chicken yet but the egg was the first chicken egg which grew into the first chicken. And so instead of this:

It would be more like: