What came first: the chicken or the egg? (debate)

...It took my third arm, and my third eye, and everything below my waist...
this you?

Need I say more?
Actually egg before dinosaurs because fish and stuff in the ocean, not the same kind of egg but still an egg

The egg came first. Eggs started to appear 340 million years ago, way longer than the modern chicken.

And why, again, do you believe this? Please back it up, for debates' sake.
first came the mighty Egg Chicken, a beast so mighty it slew King Arthur. The Second. but I fought it back in 500 AD, and a mighty battle it was. It took my third arm, and my third eye and everything below my waist, but I slew it, and caused hundreds of both eggs and chickens to be spread throughout the world