The Evolution of the Breast

About sixty-five million years ago, at the end of the Mesozoic era and the beginning of the Cenozoic, the niche once dominated by the dinosaurs was available for other creatures. The opportunistic could move into that niche now empty of large reptiles, and prosper in their place. Among these creatures that flourished were small egg-laying animals. group that had been around for at least a million years and that sported specialized patches on their chests. Sitting on their eggs, the mothers of...