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 from around the world on a global adventure as they follow clues from the fossil record and use 21st century technology to make exciting new discoveries and change what we thought we knew about the evolution of these iconic beasts.

Watch When Whales Walked: Journeys in Deep Time, tonight at 9pm on WGBH 2.