View full lesson: http://ed.ted.com/lessons/the-game-changing-amniotic-egg-april-tucker
350 million years ago, eggs could not survive far from water, therefore animals were water-bound. That is, until the amniotic egg, which allowed animals to live a fully terrestrial life. April Tucker peels back each layer of the amniotic egg, revealing how truly extraordinary this evolutionary marvel is.
Lesson by April Tucker, animation by Pew36 Animation Studios.