Seismosaurus << SYZ muh `sawr` uhs >> was one of the largest dinosaurs that ever lived. Scientists believe it measured about 110 feet (33 meters) in length. It may have weighed about 85 tons (77 metric tons). The animal’s name comes from the Greek words for earthquake and lizard. Seismosaurus lived in what is now the western United States about 150 million years ago, near the end of the Jurassic Period. When the first Seismosaurus fossil was discovered, scientists thought Seismosaurus was closely related to a dinosaur called Diplodocus. Most scientists now consider Seismosaurus to be a kind of Diplodocus.
Seismosaurus and Diplodocus belonged to a group of huge dinosaurs called sauropods. Like other sauropods, Seismosaurus had a bulky body that tapered off into a long neck and whiplike tail. The dinosaur walked on four short legs. Because it was so large, Seismosaurus probably moved fairly slowly.
Seismosaurus ate plants. Its mouth probably had peg-shaped teeth to strip tree bark and leaves. In addition, the animal swallowed small stones called gastroliths. Gastroliths stayed in the dinosaur’s digestive system and helped it stir digestive juices or grind up its food.
The first Seismosaurus fossil, an incomplete skeleton, was found in New Mexico in 1979. The bones initially appeared to be much larger than those of Diplodocus. After scientists recovered and studied more bones, they determined that the skeleton probably belonged to a large Diplodocus.
See also: Dinosaur (Sauropods); Diplodocus; Sauropod.
