Dinosaurs Inside and Out
Abnormal Dinosaur Bones
What bone phenomena do both humans and dinosaurs share?
Humans and dinosaurs share a process called “diffuse idiopathic skeletal hyperostosis” (DISH), or when the ossification (when something becomes bony-like) of the spinal ligaments stiffens the spinal area. Although it sounds bad, it is a normal process and not recognized as a disease in either humans or dinosaurs.
Creatures such as ceratopsians, hadrosaurs, iguanodonts, pachycephalosaurs, and some sauropods all show DISH—a stiffening of the dinosaur’s tail area that made it easier to hold the tail off the ground. Dinosaurs that used their tails as weapons, such as the stegosaurs, needed them to be flexible like whips, so they do not show evidence of this spinal ligament fusion. The discovery of DISH in dinosaurs dovetails nicely with a newer theory that many dinosaurs did not drag their tails, but rather held them off the ground as a form of counter-balance.
Another bone-related phenomena humans and certain dinosaurs share is vertebral fusion, where the bones of the spine (the vertebrae) actually become joined and ossified together (as opposed to the spinal ligaments in the DISH process). In the adult ceratopsians, such as the Triceratops, this fusion was limited to the first three neck (cervical) vertebrae, leading to speculation that this was not a disease, but a developmental adaptation. Stiffening in this area may have evolved to better support the animal’s massive skull. Current fossils reveal that smaller, perhaps younger ceratopsians had incomplete fusion in this area; whereas the fusion was complete in larger, presumably older animals.