Birds have colonized every environment on Earth, and they come in an astonishing variety of shapes, colors and sizes. There are more than 10,000 species of bird alive today, so how did they come to be everywhere and so diverse? After discovering an assortment of fossils, scientists have concluded

Scientists are now discovering the earliest ancient crocodiles by tracing one branch of the vast tree of life 230 million years into the geologic period called the Triassic. And they looked nothing like the crocs alive today.

Blue whales are the biggest creatures to have ever lived on Earth. Measuring up to a hundred feet long and 200 tons in weight, they have a heart the size of a small car. But how did they get so big? Surprisingly, whales weren’t always gargantuan water-dwelling mammals. In

Today there are only three species of elephant, but 16 million years ago there were dozens. What happened to all those species? Over many millions of years, due to climate change and predation pressure from humans, elephants waned until today, where there are only three species left.

Discover the evolutionary secrets of some of the world’s most majestic creatures. From voracious crocodiles and acrobatic birds to stupendous whales and majestic elephants, WHEN WHALES WALKED follows top scientists on a global adventure as they follow clues from the fossil record and change what we thought we knew