The question of which came first, the chicken or the egg, has been a topic of debate for centuries. Here are some key points from the search results:

• Eggs evolved more than a billion years ago, whereas chickens have been around for just 10,000 years.
• The first eggs were laid by animals known as amniotes, which appeared roughly 340 million years ago.
• The first chickens evolved around 58 thousand years ago at the earliest.
• Chickens likely evolved from a subspecies of red jungle fowl around 50 million years ago.
• At some point during the domestication process, the last ancestor of modern chickens would have laid an egg containing an embryo with enough genetic differences to make it distinct from its parent species. This embryonic chicken would have developed in the not-quite-chicken egg before hatching. Then, after reaching adulthood, it would go on to lay the first proper chicken egg. In this way, the chicken could be said to predate the chicken egg.
• Dinosaurs laid eggs well before chickens were ever around.

Based on this information, it seems that eggs came before chickens. However, the question is complicated by the fact that the first chicken egg would have been laid by an animal that was not quite a chicken, but was genetically distinct enough to be considered one.