By Sean Henahan, Access Excellence

When Bruce M. Rothschild and colleagues at the Arthritis Center of Northeast Ohio, Youngstown, Ohio, analyzed the leg bones of T-rex specimen they found evidence of  bone erosion characteristic of the painful disorder known as gout. Gout is a metabolic disorder in which urate crystals accumulate in bones  and joints, often causing the development of new bone tissue. While more common in humans, where it is associated with rich food and excessive wine consumption, gout does occur in lizards and birds.

"Caricatures of the agony and ill-temper of those afflicted with gout are magnified by its recognition in Tyrannosaurus rex", said Rothschild.

This is the first report of gout in a dinosaur, although considering the red meat diet of T-rex it may not be entirely surprising. In particular, gout is associated with a diet high in the protein purine, found in large amounts in red meat. Incomplete metabolism of purines leads to excessive uric acid into the bloodstream, which eventually can crystallize in the joints causing considerable pain. .

The discovery came during an analysis of bone casts of the right forearm of a specimen popularly known as "Sue", currently residing at the Denver Museum of Natural History. This revealed bone lesions characteristic of a bad case of gout. Subsequent analysis of 13 more specimens at the Royal Tyrell Museum in Alberta, Canada, produced one more potential case of gout.

In humans, gout is often recognized by the presence of accumulations of urate crystals in the joints, often starting with the feet. The age of the dinosaur specimens precluded this approach. However, gout can also be diagnosed using x-rays. Combining macroscopic and radiological data, the researchers are confident that T-rex occasionally developed the disease.

"The uniformly excavated nature of the erosions in these specimens is characteristic of gout. Spheroid lesions with overhanging lesions, common in gout, are only rarely found in other diseases such as multi-centric reticulohistocytosis, amylodisis and type IIA hyperproteinemia," said Rothschild.

The presentation of these specimens also argues against other diseases such as rheumatoid arthritis, osteoarthritis or spondyloarthropathy, he added.

While diet may indeed have been a factor, gout is a sign of dehydration and/or renal failure in reptiles and birds respectively, so they may have also been involved in this case, he speculated.

The skeleton of poor Sue, originally discovered in South Dakota,  is to be auctioned by Sotheby's later this year. Sue had a rough life, as demonstrated by deep gashes in her facial bones, a dinosaur tooth stuck in her ribs, and broken leg that never healed properly.

Sue had also had legal troubles, being the object of a custody fight between the fossil hunter who found her and the US governement who claimed she  was found on federal land.
 
The research appeared in the May 22, 1996 issue of Nature