700 million years ago, a remarkable creature emerged for the first time. Though it may not have been much to look at by today’s standards, the animal had a front and a back, a top and a bottom. This ...

Imagine being a paleontologist exploring Utah’s Jurassic-aged rocks. Imagine discovering the bones of a 20-meter-long, 20-ton herbivorous dinosaur. Then consider: How could any beast become so big?