So what did come first, the chicken or the egg? That question has resounded throughout my entire life, yet the scientific answer is quite simple when you either read it somewhere or finally figure it out.
So, consider the issue a moment, and then follow me below Little Richard's hairdo down there to eggsamine the issue.
When I decided that it would be fun to do this and started formulating it, I realised that the persistence of the question is a mystery given that the Bible says:
So God created the great creatures of the sea and every living and moving thing with which the water teems, according to their kinds, and every winged bird according to its kind. And God saw that it was good.
(Genesis 1:21), which clearly says birds and not eggs. However, the question has persisted and resounded in spite of that clear statement, so let us see what science has to say on the matter --
Science, first and foremost, is a method or collection of methodologies, not a body of knowledge. That said, I will, nonetheless, gloss over some of the science and simply explain some of the findings.
Boatloads of evidence, study and research has led to the adoption of Evolution (by natural selection) as one of the unifying principles of science. The current model of evolutionary theory has it that birds, like other current life forms, evolved from something else. In this case that would be dinosaurs, and most likely Theropod Dinosaurs.
Such evolution isn't likely to have been instant with some late model theropod having chicken offspring - it generally doesn't work like that, and the evidence supports a more gradual progression. At some point, one or more mutations in what was to be the last theropod ancestor of the first true chicken resulted in offspring that were birds or proto-birds; the first avian ancestors of the first true chicken. In like fashion, after some intermediary avian ancestors, the last not-quite-a-chicken avian ancestor, as a result of one or more mutations had at least one offspring that was the first true chicken.
That first true chicken, like its proto-chicken avian ancestor, the very first avian ancestor in the chicken line, and the last theropod ancestor of the chicken family hatched from an egg. That is the nature of not only chickens, but their ancestors all the way back to the Jurassic. The egg came first.
Q.E.D.