If you're wondering who came first, the chicken or Trex, the answer is Trex.
A new bone find from 68 million years ago indicates that Trex was here before the chickens. And its now clear that the modern day chicken came from the Trex line.
And most likely, all our modern day birds were also survivors of Trex. But lucky for us, the modern day birds and chickens are no ware near the size of Trex. If they were, I think we'd all have a little problem.
Anyway, all these conclusions are a result of tissue found in Trex, that was somehow preserved very well, even after 68 million years. So, I guess we'll never be able to look at chickens quite the same way again.