A study by scientists from the University of Manchester and published by the Royal Society found that at least one dinosaur had severe arthritis, and the evidence indicates that the creature suffered severe pains due to this condition until the time of death.

The fossil is about 70 million years old and, according to scientists, it was a hadrosaur, a plant-eating specimen that had septic arthritis in the joints of the elbow, as showed by an X-Ray analysis made to the fossil. The New Jersey State Museum Foundation with The Richards Fund funded the investigation in order to enrich palaeopathological knowledge since identification of pathologies in the fossil record allows scientists and general public to understand extinct systems and rarities among organisms from our natural history.

Image Credit: Allen Creative / Steve Allen / Alamy/New Scientist

About the sick fossil

Scientists presented in their study a vertebrate from the Mesozoic of the East Coast of North America (Appalachia), an indeterminate hadrosaur from the Navesink Formation (New Jersey) found in Gloucester County in New Jersey.

Through X-ray studies, they discovered that the animal presented the pathologic condition affecting the proximal ulna and radius. However, scientists do not know if this were the only parts of the fossil affected with the disease since the other parts of the body were not found.

The diagnosis was based on the results of the X-ray tomography, an instrument that revealed an erosion of the joint along with an unnatural bone growth in the periosteal, features that are results of septic of arthritis. This is the first time this particular type of arthritis appears in dinosaurs fossils. The benefits of using an X-Ray tomography, specifically a microtomography, in this case, is the non-destructive character of it. While some other scientific techniques to analyze samples require destruction of the bone of body part under study, this type of tomography preserves the part without harming it and allowing the scientist to conserve the specimen digitally.

This particular specimen is also rare since the fossil record for Mesozoic terrestrial animals is not very rich, so there are not that many hadrosaurs to compare the physical structure and the behavior of the affection in comparison to others.

The ulna of the hadrosaur measured more than 670 mm while the radius measures 535 mm. The parts were found joint together but for scientific purposes, they were separated once under study.

A significant finding among the darkness

This discovery was relevant considering that the majority of information about Mesozoic fauna is composed solely of skeletal remains that are not enough to make deep conclusions about these particular type of fossils. Eastern North America had through the history some environmental conditions that affected the conservation of fossils, so most, remains are severely fragmented or infected with different diseases or conditions that make them fragile and impossible to manipulate for scientific purposes.

This reality opposes, however, to the relevance of the East Coast specimens, since New Jersey represents an important center for academic vertebrate paleontology in the Americas, and the Mesozoic territory in the East is one of the primary fields studied by New Jersey’s scientists.

XMT scans of the hadrosaur ulna in longitudinal and transverse views. Image Credit: Royal Society

The significant contribution to Palaeopathology

While paleontology is the study of extinct life forms and systems that lived about 12,000 years before the present time, through scientific methods, palaeopathology responds to researching and studying about ancient diseases and trauma, to comprehend the immunology system and the biological background of extinct species.  This finding has made a major contribution to the latter, due to the rarity of the specimen and its condition.

Given the provenance and pathological condition, this fossil represents a major discovery to those who study bone conditions in extinct vertebrates. This type of research is performed more frequently since it’s more accessible to scientists reaching physical data and diagnose conditions in existing pieces, like bone fragments than analyze conditions in soft tissues that can not be preserved.

The diagnosis

The projection of the bone, the structure of the radial articulation and the overall surface of the bones were analyzed, both with an internal and external examination. The reactive bone growth was the first condition diagnosed. The scan revealed the extent of the lesions along the radius and the ulna articular surface. The texture of some areas and the tissue orientation were also abnormal.

The final brochure of the investigation, before ruling out several possible conditions linked to the state of the body parts studied, states as the diagnosis the following:

The ulna and radius show signs of both excessive bone necrosis and reactive (pathological) bone growth, which can be attributed to several conditions seen in reptiles and birds. The most likely explanation for the given pathology is a form of osteoarthritis, as reported by The Royal Society.

All data related to the investigation is available on line.

Source: Royal Society