I'm glad you couldn't tell! It's basically tongue in cheek, as the question is silly to begin with.

And of course eggs predate chicken, eggs are seriously old technology.

Back to the tongue in cheek: there is something easily tautological that chickens come from eggs. At some point a non-chicken laid an egg, and the first chicken was born from it. This is true regardless of which mutation one decides is "the" mutation that makes for the "first" chicken.

QED it's the egg