Dinosaur arthritis: A diagnosis a few million years too late

Apparently dinosaurs, like so many of us, had achy joints, according to several studies conducted in recent decades.

In 1997, researchers led by Bruce M. Rothschild, MD, Arthritis Center of Northeast Ohio, Youngstown, OH, found that a Tyrannosaurus rex nicknamed Sue that was unearthed in 1990 from a butte in South Dakota may have had gout. They published their results in Nature.

Dr. Rothschild et al. based their diagnosis on findings from Sue’s skeleton, one of the most complete tyrannosaurus skeletons ever discovered. Specifically, they found lesions similar to those seen in modern day birds, reptiles, and even humans with gout.

In research presented at the 2017 Society of Vertebrate Paleontology meeting in Calgary, Alberta, researchers found evidence of spondylarthropathy in a hadrosaurid unearthed in the Milk River Ridge Reservoir, an artificial lake in southern Alberta, Canada. Its fused, textured, and pitted dorsal vertebrae led to a diagnosis of spondyloarthropathy, which has also been found in other dinosaurs.

Most recently, researchers led by Jennifer Anné, PhD, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK, took a specimen from a hadrosaur that consisted of a 675-mm ulna and 535-mm radius found fused together in the Hungerford and Inversand Quarry in Gloucester County, NJ. Using a Nikon Metrology HMXST225 Micro CT system, they scanned the proximal ends of the bones and compared the results with known conditions in existing birds and reptiles for their diagnosis of pathological conditions.

Both the ulna and radius carried signs of excessive bone necrosis and pathological bone growth. In the ulna, they found the most severe effects in the first 14 cm of the proximal end, and these extended almost half the length of the bone. Heavy remodeling was evident, causing a ”cauliflower-like” texture, which was particularly evident around the articular surfaces, where one large and several smaller necrotic lesions were found proximally.

Dr. Anné and colleagues narrowed the underlying etiology of this damage down to two osteoarthritic conditions—osteomyelitis and septic arthritis. They settled on septic arthritis due to the erosion evident in both bones and the pathological bone growth and fusion.

“Our interpretation is necrosis and remodeling of the elbow joint was caused by the loss of articular cartilage due to septic arthritis. The weakening and eventual destruction of the joint caused pathologic bone growth and ankylosis of bone acting in response to the pathology in order to strengthen the joint,” they wrote.

“Thus, we interpret septic arthritis as the cause of the pathology found in NJSM GP11961 [the hadrosaurid’s identification code], making this the first documented case of this condition within the non-avian Dinosauria. This interpretation was only made possible by using the combination of internal morphologies achieved through XMT [x-ray microtomography], as well as the use of comparable extant species for interpretation of the condition,” they added.

All leading to the big question of what really killed the dinosaurs? While it’s clear that a catastrophic die-off took place around 66 million years ago, what was its cause? Scientists have suggested an asteroid and its resulting supervolcanic event, global plagues, or perhaps even a supernova frying the planet as the culprit. What is known now is that T. Rex and many of her compatriots suffered from conditions eerily similar to those we still see today.

Dr. Anné’s research was supported by financial support from The Richards Fund, held in trust by the New Jersey State Museum Foundation.

Sources:

Browne MW. “Pity a tyrannosaur? Sue had gout.” New York Times. May 22, 1997. https://www.nytimes.com/1997/05/22/us/pity-a-tyrannosaur-sue-had-gout.html. Accessed June 12, 2018.

Geggel L. “Dinosaur gets strange diagnosis 78 million years after its death.” LIVESCIENCE. Sept. 14, 2017. https://www.livescience.com/60413-duck-billed-dinosaur-sick-with-joint-disease.html. Accessed June 12, 2018.