The chicken of course. Why, do you think the egg laid itself? You see, a male and a female chicken climbed out of the premadoral soup, and began laying eggs. That's how evolution theory works anyways. And this happened, -despite the odds of it happening even once being trillions and zillions against it- millions of times over.
You've confused creationism with evolution. Creationists believe -- ZAP -- on the fourth day, two chickens climbed out of the "premadoral [sic] soup" (my bad -- out of the "dust of the ground") and started laying eggs.
Scientists, on the other hand, don't think chickens evolved ex nihilo. They believe billions of small changes over billions of years led to birds with a mixture of primitive and derived traits that we can isolate as chickens. No generation of chickens looked much different from its parents, but changes built up over time.