S34 Ep7: Did This Thighbone Belong to the World's Largest Di

Aired: 2/17/2016 | 0:00:54 | Clip
Sauropods were long-necked, plant-eating dinosaurs that started off relatively small. However, after 20 million years of evolution, they grew to enormous proportions. Naturalist David Attenborough compares the thighbones of early sauropods to the largest ever found.