The chickens come from eggs, then chicks come. When they grow up, they turn into Then they make more eggs. More chicks. They grow up, have more, making more chicks. It's a whole life cycle of confusion. But the chicken came first.
Something laid an egg and out popped this one odd little chick. The mama was probably a similar bird - close but not quite the same. Her baby was a little different & cooler than the other babies, that's all. Now we all love chicken! (You oddballs out there better run for your lives, ha ha!) : )
It has to be the egg (if you believe in evolution) because the chicken species evolved from something else before them, so the egg was laid by something very closely evolved to a chicken and the egg was the first of that species.
Well some dinosaurs laid eggs, which would make it the egg that came first. If you mean a chicken egg, it's still the egg which was first. The egg in question would have likely been laid by an animal that's was extremely similar to a chicken, but was not. When this egg was laid all depends on your cut-off point on what you'd label a chicken.