From The Land Before Time to Jurassic Park, images of fantastically large, long-necked, plant-eating dinosaurs have captured our imaginations. These are the sauropods: centerpieces of museums and gentle giants of the distant past. Imagine what it must have been like to crest a hill and see in the valley below not just one sauropod, but an entire herd, feeding its way across the landscape.
The most massive land animals ever to have lived, sauropods roamed widely across the continents through most of the "Age of Dinosaurs" from about 220 to 65 million years ago. They reached incredible sizes, giving rise to the question: Why were they so big? Early guesses suggested that they gained protection from predators by virtue of their size, which also allowed them to reach the tops of trees in order to eat leaves and conifer needles. More recent hypotheses hold that they needed a long and complicated digestive tract due to their consumption of low-nutrient food...