An international team of scientists has successfully, albeit belatedly, diagnosed a rare disease in very special patient: a dinosaur who lived around 75 million years ago. The unfortunate hadrosaur suffered from a rare form of cancer that continues to afflict humans and animals today, they deduced.
Studying the vertebrae of a hadrosaur found in Canada, the researchers observed that two of the bones presented large cavities and lesions, and deduced that these had been caused by tumors associated with Langerhans cell histiocytosis, or LCH.
This rare disease can cause growths to form in various tissues almost anywhere in the body.
The team, which included American, Canadian, Israeli and Swiss experts, presented their findings in a paper published Monday in Nature – Scientific Reports.
Hadrosaurs were a large family of herbivorous dinosaurs which were common throughout the world in the Late Cretaceous, from around 90 million years ago to 65 million years ago. They are often known as duck-billed dinosaurs because of the flat, duck-like appearance of their snouts.
The vertebrae of the hadrosaur in question were unearthed in Dinosaur Provincial Park in southern Alberta, Canada, a fossil-rich site that has yielded more than 150 complete skeletons of the giant reptiles.
In the case of the ailing dinosaur, only 11 vertebrae from the beast’s tail were recovered, the paper says.
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The discoverers of this particular hadrosaur noted that two of its vertebrae “had large holes that looked very strange and didn’t look like any growth they were familiar with,” explains Dr. Hila May, a physical anthropologist from Tel Aviv University who took part in the study.
While it can often be difficult for experts to identify a specific disease just by looking at bones – whether they be of dinosaurs or humans – in this case they hit upon a pathology that, although rare, leaves some very distinctive marks, May says.
Led by Prof. Bruce Rothschild of Indiana University, a rheumatologist who studies the origin and spread of diseases, the team realized those holes where very similar to those produced by tumors connected to LCH.
This illness, whose cause remains unknown, involves the abnormal proliferation of dendritic cells, which are part of the immune system. The uncontrolled buildup of these cells can occur in multiple body parts, from bones to lymph nodes to the central nervous system, leading tumors to form that can damage other tissues and form lesions.
The soft tissues that formed the tumors in the ailing hadrosaur decomposed millions of years ago but left behind the space they had carved for themselves in the dinosaur’s vertebrae, May explains.
The scientists were able to confirm their hypothesis by comparing the dinosaur’s remains to those of humans known to have been affected by LCH in their bones. They also produced a micro-CT scan that allowed them to reconstruct in 3D the now missing tumors and even the tiny blood vessels that fed them.
“The micro and macro analyses confirmed that it was, in fact, LCH,” May says. “This is the first time this disease has been identified in a dinosaur.”
In humans, LCH tends to affect young children. While the tumors it causes can be very painful, they are treatable and in some cases even disappear on their own, the anthropologist says.
This was probably also the case with dinosaurs, says Rothschild. While the hadrosaur was a young specimen, it probably did not die from the disease – although we do not know what ultimately killed it, he says.
This is not the first time that a specific ailment has been identified in dinosaurs. The mighty Tyrannosaurs could be crippled by gout and Iguanodon is known to have suffered from arthritis. Cancers like osteosarcoma have also been previously observed in dinosaurs and even in their evolutionary predecessors, such as a 240-million-year-old ancestor of modern turtles.
But the discovery that a particularly rare disease like LCH was present so long ago and affects wildly different species across tens of millions of years pretty much in the same way opens up new avenues of research into the evolution and origin of such diseases, the researchers say.
“Ultimately, the goal of such studies is to understand the real cause of these illnesses and what evolutionary mechanisms allowed them to develop and survive,” says Israel Hershkovitz, an anthropologist and paleopathologist at Tel Aviv University. “Perhaps if we understand a disease’s underlying mechanisms we can treat its causes more effectively, instead of focusing on the symptoms, as modern medicine tends to do.”
Paleopathology, the study of ancient illnesses, has been enjoying a renaissance of late thanks to the application of genetic research, high-tech imaging and other advanced scientific methods. This has led scientists to multiple breakthroughs such as sequencing the genome of the bubonic plague and identifying the oldest known cases of tuberculosis. These studies, researchers say, don’t just give us precious information on the lives and deaths of ancient peoples. They also help us track the origin and mutation of diseases, helping us understand their spread and possibly offering clues on how to combat them.