Ever wondered what the answer is to the question "what came first, the chicken or the egg?"
Well, wonder no more.
There are two answers, which one you accept depends on your world-view.
For the creationist: God created chickens in Genesis, not eggs, chickens. He created fully formed men, animals, fish, plants, etc, all adult. Thus the chicken came first. Could it have been an inaccuracy and god actually created eggs instead? well, no... because chicken eggs die unless they are incubated by the body heat of an adult chicken. Thus creating merely eggs would have resulted in a bunch of dead eggs, not chickens. There might be some religions in which both were created simultaneously, but you cannot have just eggs.
For the scientist: Evolution is the process of the formation of species (not life, species!). It is rather more of a continuum, but at some point there is one singular mutation that made a large enough difference for you to draw the arbitrary line saying "this is a chicken" and not its dinosaur precursor... No matter where you decide to draw that line, it will always be a mutation in a new individual. A mutant sperm or egg will form a zygote that will form a new individual with DNA that differs from its parent. Thus the egg came first.