Chicken and the egg
Question: what came first, the chicken or the egg?
Answer: first came the egg: fish, amphibian and reptiles all leg eggs, therefore, the egg came first. Also, can you imagine that a reptile (e.g. crocodile) changes from one day to the other into a chicken, then to lay an egg so a new chicken will be born. No, it was easier for nature to have a mutation during the development of an animal so that a new species (chicken) was formed. Of course, this took place over a longer period (mutations took place over time, giving rise over time to a new species).
In case someone has another view on this, please let me know and I might rethink my answer.