Of course, chicken. This is quite obvious as to appear offspring, parent to appear. The answer is in the Bible, and recently science has succeeded in finally convincing to prove this fact.
In the ovaries of chicken produced protein called Ovocleidin-17. With the help of computer scientists have studied in detail the formation of the shell, and came to the conclusion that this protein plays a key role in this process. The shell egg is composed of 90% calcium carbonate, and contains a lot of trace elements such as copper, fluoride, iron, manganese, molybdenum, phosphorus, sulfur, zinc, silicon and others, but it all gets out of chicken meal. But Ovocleidin-17 is produced only of the chicken, so, in order to display the egg, it is absolutely necessary.
Of course, the question, "Which came first? .." Rather philosophical and rhetorical, but now we have a science-based answer to it.