National Geographic: Darwin's Lost Voyage (2008)

National Geographic documentary looking at the discoveries made by 19th century naturalist Charles Darwin in the wilds of South America in the period following his visit to the Galapagos islands. Among the questions pondered by Darwin during this time are: Why do the fossils he discovers look like giant versions of the sloths and armadillos still living nearby; why do the penguins and other birds he sees use their wings as flippers, fins or sails - but not for flying; and how could sea shells be found embedded in rock layers more than 100 miles from the sea?