Discovered in 1979 by two hikers in New Mexico, Seismosaurus was even bigger than Ultrasaurus or Supersaurus—a giant sauropod estimated to have been 150 feet long and to have weighed ten EEUs (Equivalent Elephant Units), approximately 50 tons. In 1985, paleontologists armed with computers and sophisticated sound wave tracking devices began the difficult process of freeing the giant fossils from tons of sandstone; the author, a paleontologist involved with the dig, also explains how scientists use everything from pick and shovel to neutron scattering accelerators to learn more about dinosaurs. Nature artist Hallett's paintings of the great creatures in their heyday are complemented by 30 excellent color photos from the dig. A splendid blend of adventure and science. Index. (Nonfiction. 10-14)