Period: Late Jurassic


Order, Suborder, Family: Saurischia, Sauropodomorpha, Diplodocidae

Location: North America (United States)

Length: 120-140 feet (36-42.5 meters)

Nearly half as long as a football field, Seismosaurus is possibly the largest dinosaur from North America. The single skeleton of this genus was excavated in central New Mexico. It was given its name because of its great size-"earth shaker reptile."

This giant sauropod reached an estimated length of 120-140 feet. If this is correct, it is the record length for a dinosaur. The skeleton is mostly joined (articulated) and consists of the front half of the tail, the pelvis and sacrum, and the vertebrae in the rib-bearing region. In future excavations, paleontologists hope to recover the front legs, neck, and skull. Some paleontologists feel that the partial Sesimosaurus skeleton simply represents a particularly large specimen of Diplodocus.

Like other diplodocids, Seismosaurus probably had a long slender neck, large bulky body, short front legs, tall rear legs, and long heavy tail. "Stomach stones," or gastroliths, have been found with the skeleton. It is one of the few articulated (joined) sauropod skeletons that had gastroliths in place when it was excavated.