Scientists at Sandia Laboratories working with  paleontologists at the New Mexico Museum of Natural History and Science used CT scans of the structure of the bone-headed dinosaur's skull to recreate the sounds of the long-silent dinosaur. The eerie sounds were played for the first time at a press conference today.

Graphic: I am Parasaurolophus, hear me roar.

Paleontologists excavate the fossil of the head crest of the dinosaur in Northwest New Mexico in August 1995. Later, the fossil was scanned using X-ray computed tomography, and a three-dimensional computer model of the crest was generated. Having determined the size and shape of the air passages in the skull crest, the scientists used computer muscle power to determine the natural frequency of the sound waves the dinosaur could have made.

"The sound may have been somewhat birdlike, and it's probably not unreasonable to think they did songs of some sort to call one another. Fossil records of the large bones in the dinosaur's ears compared to corresponding bones in human ears suggests they were able to hear lower frequencies than humans," said computer scientist Carl Diegert.

The crest is five and a half feet long and contains a labyrinth of air passages. The computer modeling suggest the dinosaur emitted a low-frequency rumbling sound that could vary in in pitch. The scientists speculate that each Parasaurolophus probably had a unique voice, and that the species may have been quite sociable. No one knows whether the dinosaur had vocal cords or what kind of soft tissue made up the inside of the head and throat. Using their imaginations freely, the scientists created a variety of sounds simulating both the presence and absence of vocal cords.

The scientists used the CT scanning technology to create a series of  350 cross sections of the skull and crest at 3mm intervals. The research revealed a much more complicated internal structure than had been previously predicted.

"Not only are there more tubes than the simple, trombone-like loops described in previous studies, but there are new chambers within the crest," said Tom Williamson, curator of paleontology for the New Mexico Museum of Natural History and Science in Albuquerque, NM.

Parasaurolophus makes a cameo appearance in the film Jurassic Park. The dinosaur lived during the Late Cretaceous Period, about 75 million years ago. Although hadrosaurs were the most abundant of the large plant-eating dinosaurs of that period, fossils of a few kinds of hadrosaur dinosaurs, including Parasaurolophus, are very rare. The animals remain relatively poorly understood. Remains of two or three species (the exact number is still disputed) of Parasaurolophus have been discovered, and little is known about the amount of variation present within each species.

Graphic: Parasaurolophus crest, foreground, reveals several tubes or air passages that run through it. In the background is the crest fossil. (Photo by Randy Montoya)

The computer imaging studies may also help answer other questions about Parasaurolophus. There has been long-standing disagreement over the possibility of warm-blooded dinosaurs. Williamson says he will be looking for turbinate bones in the air passages of the dinosaur. Almost all warm-blooded animals have turbinate bones, and no existing cold-blooded animal has them.

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