Chicken or the Egg finally proved

The parent of the first chicken was not a chicken.

The parent laid the egg.

The embryo, while developing, undergone a mutation.

Instead of developing into like its parents, the embryo developed into a chicken.

According to evolution, anyways.

I'm entirely sure that that is not how evolution works. You're not going to have direct Dinosaur Egg -> Chicken. It'd be a series of small mutations and variences in DNA with favorable traits for the time that created the chicken.