Did you know that polar bears evolved from brown bears? Or that chickens are the descendants of tyrannosaurus rex? Did you hear that the nambaroo, the ancestor of the kangaroo, had fangs and moved on four legs?
We here at HuffPost Green love animals, which is why we decided to create a slideshow of unexpected animal evolution stories. As always, we want to hear from you. Tell us about your favorite interesting animal evolutions in the comments.