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Paleontologists Assess T. rex Sue's Pathologies

Though often depicted as an indomitable killing machine, Tyrannosaurus rex was not immune to trauma and disease. Indeed, the famously complete specimen known as Sue bears a number of pathologies that have long intrigued researchers. Now a new analysis, the results of which were presented last Friday at the annual meeting of the Society of Vertebrate Paleontology in Bozeman, Montana, suggests that Sue suffered from diseases similar to ones that afflict animals today.

In addition to healed fractures in several of the ribs and bone spurs in the backbone and tail, Sue's skeleton shows signs of infection of the lower leg and right upper arm bones and curious holes in the lower jaw. Previously, researchers had attributed the jaw injuries to bite marks. But paleontologists Elizabeth Rega of the Western University of Health Sciences in Pomona, Calif., and Chris Brochu of the University of Iowa report that the shape of the lesions, their distribution pattern, and the fact that similar lesions appear in a number of tyrannosaurid specimens instead hint that they may have resulted from something similar to actiniomycosis, a fungus-like bacteria that infects the bone and soft tissue in the mouths of modern cattle. "The fact that this disease is part of the ecosystem of the mouth in modern affected animals," Rega observes, "further suggests the exciting possibility that a bacterial 'venom' similar to that in the mouths of Komodo dragons may have been present in T. rex as well."

Rega and Brochu note that although Sue's remains bear numerous indications of trauma and disease, this does not indicate that Sue was unhealthy. Rather, they conclude, the beast's maturity and clear evidence of healing indicate that Sue "was a robust individual who successfully survived many insults." The researchers further assert that the manner in which Sue's bones responded to disease has more in common with the approach taken by birds and mammals than by reptiles. This could bolster arguments that T. rex led a metabolically active lifestyle similar to that of today's warm-blooded animals.

"Breathing Life into Tyrannosaurus rex," by Gregory M. Erickson (Scientific American, September 1999), is available for purchase at the Scientific American Archive.
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