While eating a hard-boiled egg, I started to think about its nutritional value. For instance, the amount of calcium in the yolk and white. There must be enough calcium and other materials to create the skeleton of a baby chick. The more I thought about it, the more I wondered how the contents of an egg get transformed into a baby chick. It’s a closed system, unlike the uterus of a mammal. It seems like the contents of the egg are transformed into a baby chick with great efficiency. How does this happen, and where do the waste products go?
From here
“…With the embryo closed off from the outside world by the shell,2 there is the problem of how to dispose of excretory wastes. Here is where the allantois is so crucial, as it serves as the embryo’s garbage bag. (When the chick hatches, the accumulated wastes can be found sticking to the inside of the abandoned shell.)”
I was expecting something new about the “What came first?” debate when I read the thread title, but I was disappointed.
The egg.
The chicken.
Yes, but only after the egg.
Yes, but only after the chicken.
Yes, but only after the egg.
The chicken came first, according to the site cited by CoG888.
Answers in Genesis? Was that the most reliable site you could come up with?
Well, last time I saw the cartoon, it was the egg contentedly smoking a cigarette, and the chicken looking disgruntled (or disclucked) and say “Well, I guess we settled that question”.
That’s why an egg is such good food. It has to contain all the necessary ingredients - nutrients and elements - to create a fully functional miniature chicken (or other species, as applicable). It doesn’t really contain much waste, because the chick isn’t digesting raw materials with the expectation of absorbing the needed material and excreting the rest.
I can’t come up with a “more reliable” site, sorry. All the references in the article are either dead ends or broken links. I don’t have access to the book that their facts likely came from (Curtis, H., Biology, 4th Ed., Worth Publishers, New York, pp. 859-864, 1983), and my google-scholar-fu isn’t good enough. I am not headed to the library anytime soon either. So, I retract my previous answer about waste products in the egg.
However, while searching for a better source, I found the answer to another of the OP’s questions…
“… The final stage, the making of the shell, occurs in the uterus, or shell gland, and takes about 14 hours. The shell is about 4% protein and 95% calcium carbonate, materials which again are secreted by the surrounding tissue. Much of the Calcium needed is removed from the honeycomb-like structure of the hen’s own bones. The principle function of the shell, of course, is mechanical protection, though the embryo does derive some calcium from it. Since the enclosed embryo is alive and, although it can not breathe, needs a constant supply of air, the shell is porous and allows oxygen to pass in, carbon dioxide to pass out…”
Harold McGee, “On Food and Cooking: the Science and Lore of the Kitchen.” Fireside, New York, 1984, page 61.
I should have added a smiley. Your cite was accurate enough for the most part; the stuff about evolution, not so much.
Here’s a more complete (and more reliable 
) cite: http://chickscope.beckman.uiuc.edu/explore/embryology/day04/4Focuson_1.html
Or the reptile.
The creature with the machinery to lay an egg had to come before the first egg was laid.
QED!