National Geographic : 1993 Jan
The right light makes all the difference to Dave Thomas as he frees a Seismosaurus from New Mexico sandstone as hard as concrete. In day light he can hardly distin guish fossil from stone, but under ultraviolet light the fossil glows. With magnify ing glass and dental pick, he removes the stone bit by bit, uncovering just a few square inches of dinosaur a day. At that rate it will take at least ten more years to prepare this fossil for display. One of the longest dinosaurs ever found, Seismosaurus may have measured 150 feet from nose to tail.