Dinosaurs may have been extinct for about 245 and 66 million years ago, in a time known as the Mesozoic Era, but there are many reasons why researchers continue to study their ancient remains. Aside from giving us a concept of “deep time” and associate clues about evolution and ecosystems, dinosaur research also matters in medicine, a team of researchers from the University of Bonn in Germany finds.
The bridge between paleontology and medicine
In their study, which appeared in Scientific Reports, Tanja Wintrich from the Section Paleontology of the University of Bonn and the team explained that it has always been assumed that only humans and other mammals have discs. In humans, there are 23 discs in the spine and they allow slight movement of the vertebrae and act as a ligament to hold them together. But Wintrich and team discovered that it is a misconception as even Tyrannosaurus Rex, a genus of coelurosaurian theropod dinosaurs, could have also suffered a slipped disc.
Snakes and other reptiles don’t have intervertebral discs (IVD). Their vertebrates are instead connected with ball-and-socket joints. In vertebrate anatomy, the end surface of their vertebra fits into the cup-shape depression of the adjacent vertebra like the human hip joint. In between these are the synovial fluid and cartilage that keep the joint mobile.
Paleontologist Dr. Tanja Wintrich told Science Daily that she finds it hard to believe that ancient reptiles do not have IVD. During their study, most of the vertebrae of ancient marine reptiles and dinosaurs look the same as those of humans in the sense that they do not have the ball-and-socket joints. She wondered whether dinosaurs also had intervertebral discs and were just replaced with ball-and-socket by evolution.
The vertebrae of dinosaurs
So, the team examined 19 different dinosaurs, some animals that are still alive today, and other extinct reptiles. The paleohistological sampling of the extinct clades revealed the preservation of different intervertebral soft tissue types (probable notochord and cartilage). They concluded by examining bone histology, preserved soft tissues, and articular surface morphology that IVD does not only occur in mammals.
Dr. Wintrich has also demonstrated that the remnants of cartilage and other parts of the IVD are almost always preserved in ancient specimens, including dinosaurs like Tyrannosaurus and reptiles like ichthyosaurs. She also traced the evolution of soft tissue between the vertebrae along the family tree of land animals, which split into the bird line, dinosaur line, and the mammalian line about 310 million years ago, details Science Daily.
Previously, it was unknown that IVDs are a very ancient feature but with the team’s study, they found out that IVD emerged several times during the evolution of different animals. They believe that IVDs were probably replaced by ball-and-socket joints twice in reptiles. The reason why it happened might be because it was more susceptible to damage compared to the ball-and-socket joint. Nevertheless, mammals have always retained the IVDs, repeating the same pattern that they are rather limited in terms of evolutionary flexibility.
Importance of their study in medicine
Dr. Wintrich added that their findings are important in the field of medicine. The human body is not perfect and the existence of diseases has been evident in our long evolutionary history. For their study, they focused on medical anatomy, paleontology, zoology, and developmental biology. The dinosaur bones that were cut with a rock saw were then grounded to a thickness of 50-80 µm. Then, the researchers put it under a microscope, and there they found information that is comparable to the histological sections of embedded and fixed tissue of extant animals (still in existence). This makes it possible for the group to connect the long periods of evolution and better understand the developmental processes.
Co-author Prof. Martin Sander from the Institute of Geosciences states it is “truly amazing” that the cartilage of the joint and even the IVD itself can survive even after hundreds of millions of years.
The discovery is of eminent clinical and biomechanical importance in the human vertebral column and has also been studied from multiple perspectives in veterinary science, medical, and biological field. The most important function of the IVD is to withstand forces acting on the axial skeleton. The gradual failure of IVD as part of the degenerative processes usually leads to pathological symptoms (physiological or anatomical conditions and the subjective or objective manifestations of the disease), their study reads.
Anatomist Prof. Dr. Karl Schilling, who was not involved in the study, opined that the link between medicine and paleontology is seminal in Germany. In contrast in the USA, evolutionary biologists and dinosaur researchers are usually closely involved in medical training, particularly in embryology and anatomy. This provides young doctors the perspective that is becoming increasingly significant in a rapidly changing environment.
Incidence of a herniated disc
According to the United Kingdom National Health Service (NHS), a slipped or herniated disc happens when a soft cushion of tissue between the bones in the spine pushes out. It is painful if it presses on nerves. The incidence of a herniated disc is about 5 to 20 cases per 1,000 adults annually and is most common in people in their third to the fifth decade of life.
The two most common causes for a slipped or herniated disc are natural degeneration, which causes the nucleus pulposus to become less hydrated and weaken with age, and trauma to the disc. It may be due to lifting a heavy load using incorrect posture or from external forces, including a whiplash injury.
Meanwhile, Statista surveyed 711 US adults who suffered back pain at least once per month. It was found that 29% of respondents believed stress was the cause of their back pain. Other causes mentioned were not enough exercise or weak muscles (26%), physical work (26%), overweight (25%), spinal disc herniation (21%), sitting at a desk at work (20%), accident (17%), genetic predisposition (11%), too much exercise (9%), and psychosomatic illness (4%).
The methods commonly used for relieving back pain are painkillers (49%), physical rest in everyday life and at work (32%), specific back exercise at home (30%), move a bit more in everyday life (28%), and analgesic ointments or heat patches (25%), among others. Spine Universe also published that car crash (39.3%) is the top cause of traumatic spinal cord injury.
Dinosaurs are long-lasting champions of persistence and resilience. The University of Bonn research shows how the fossil records of these diverse groups of reptiles provide us insight into the history of the planet and a better medical understanding of human anatomy.