Scientists at Sandia National Laboratories and the New Mexico Museum of Natural History and Science have collaborated to recreate the sound a dinosaur made 75 million years ago. The low-frequency sound was produced using computed tomography (CT scans) and powerful computers. The study of dinosaur vocalization began after the discovery in August 1995 of a rare Parasaurolophus skull fossil measuring about 4.5 feet long. The dinosaur had a bony tubular crest that extended back from the top of its head. Many scientists have believed the crest, containing a labyrinth of air cavities and shaped something like a trombone, might have been used to produce distinctive sounds. As expected, based on the structure of the crest, the dinosaur apparently emitted a resonating low-frequency rumbling sound that can change in pitch. The sound is an approximation of the possible tones that the dinosaur crest was capable of producing. The computer-modeling techniques used to create the dinosaur sound are the same ones Sandia uses to create complex, three-dimensional models for conducting computer simulations of problems that cannot be subjected to real-world tests. The same 3-D imaging techniques can be used to analyze and predict the structural integrity of mounting brackets on aging airplanes, the internal structures of aging weapons, and the accurate reconstruction of the forces and mechanical failures associated with the crash of an airplane carrying nuclear weapons. For more information, contact Carl Diegert, Sandia, at (505) 845-7193.