To Egg or Not to Egg: That is the Evolutionary Question
A young lizard crawls over the eggs of its brethren. (Photo: Yin Qi)
The old riddle “Which came first, the chicken or the egg?” is not much of a riddle to biologists. The shelled amniote egg, which is familiar to many of us as chicken eggs, evolved about 325 million years ago. The wild ancestors of chickens, in contrast, only appe... 
