A look at the evolution of an animal we all know and love -- the penguin. Known for a complex social hierarchy as well as their ability to withstand some of the most harsh temperatures in nature, penguins have proven themselves among one of the most adaptable species on the planet.

Penguins: The Story of the Bird that wanted to be Fish

Elefants are the largest land animals on our planet. They appeared on Earth 50 million years ago, long before human beings emerged as a species, and were distributed all over the world to the very limit of permafrost. They are strong, intelligent and  have powerful adaptive weapons. But their evolutionary success is due, more than any other factor, to their extraordinary family ties.

Elephants, the twilight of the giants

Crocodiles appeared about two hundred million years ago. They coexisted and hunted the large dinosaurs and are the last survivors of the group of archosaurs, which means "ruling reptiles", a group that also included the dinosaurs and pterosaurs - flying dinosaurs - and more. They overcame geological cataclysms, planetary climatic changes, continental drift and even humans action. What made them surpass all their contemporaries and last until today?