I was discussing with someone and she asked me categorically, which came first; the Chicken or the Chicken-Egg. This question is logical and also has to do a little with science but if I were to anser this as plain as it is, the Egg should be the first to come as the Egg would always precede the chick.
Do you know that crossing two different animals of the same genus could give another animal of different specie. Crossing a Horse (E.f. caballus) and a Donkey (E.africanus), it could produce a Mule. Was it not possible that there was a cross between two bird of different species only to produce the chicken egg which became the chick.
Also, another way to see it is mutation. there is a possibility that the chicken came before the egg. Giraffes were said to be short necked before but with needs increasing, Giraffes started changing and mutation occurred. There is a possibility that the Chicken started changing gradually till it got to its current position or maybe it mutated gradually just like humans mutated from Ape which means the Egg could have been the first to show up.