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!

Seismosaurus ("Earth-shaking lizard")
Locality found: New Mexico
Age: Late Jurassic, 145 mya
Size: over 120 feet long and 30 tons
Diet: plants
Characteristics: huge body, with a long neck, long tail, and four short legs; one of the longest dinosaurs ever found

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