Of all the dinosaurs to roam the Earth, the largest ones belonged to a group called sauropods—huge plant-eating dinosaurs with long necks and small heads. And of all the sauropods, the real giants were the diplodocids. One of the longest dinosaurs ever discovered was a diplodocid found in northern New Mexico. This giant, called Seismosaurus, grew to be over 120 feet long-almost half the length of a football field!

Image credits: main image, Sean Murtha; Sterling Nesbitt: courtesy of AMNH.