Dinosaurs continue to fascinate us. From time to time we discover a fossil that reveals some new facts about their lives – for example their diet, injuries or habitats. However, some fossils also indicate diseases that affected dinosaurs. Yes, these animals also had their own diseases, just like any other living thing out there.
The diseases devastated the dinosaur population and even killed a good number of them. Many of these diseases still exist today and some even affect people, which makes things more interesting. We also recorded some early reptiles that lived around the time of the dinosaurs.
A 125 million-year-old dinosaur is the oldest known creature that has suffered from dandruff. This dinosaur is the Microraptor, a small carnivore the size of a modern crow. Scientists have also found evidence of dandruff in two other dinosaurs, the Beipiaosaurus and the Sinornithosaurus. Both were about twice the size of the microraptor.
The researchers randomly discovered clumps of dandruff as they examined how dinosaurs released their feathers. They found that some parts of the fossil feathers contained corneocytes. This has been a major problem, as shingles on the human skin also produce corneocytes.
The researchers did not call it dandruff, since it was thought that corneocytes and dandruff only formed on the skin and not on feathers. The researchers also found that dinosaurs lay their feathers in small pieces – just like modern birds – rather than in larger pieces, as they would have expected for their size. 
Dinosaurs had a fair share of cancer, too. This was the result of a study by Bruce Rothschild of the Medical College of Northeastern Ohio Universities in Rootstown, Ohio. Rothschild and his team made the discovery after scanning 10,000 dinosaur fossils stored in several museums in North America with an X-ray machine.
The researchers found that 29 of the 97 tested hadrosaur bone contained cancerous tumors. To be clear, not all tumors are cancerous. These were classified as cancerous because they resembled tumors found in human cancer patients.
The researchers do not know why the hadrosaurs often suffered from cancer. However, they believe that it was due to the conifers that were eaten by these animals. The conifer is a plant with needle-shaped leaves known to contain carcinogenic chemicals. 
Malaria has been killing living organisms since the time of the dinosaurs. Some researchers, such as George Poinar Jr., an entomologist from Oregon State University, even believe he killed dinosaurs. Interestingly, this malaria version was transmitted by flying insects that were probably not mosquitoes. Researchers know that a now extinct mosquito, a small flying insect living in river basins, has transmitted this earlier version of malaria 140 million years ago. However, they also suspect that sand and brakes have also transmitted malaria.
These flying insects would have bitten the dinosaurs they probably considered as the main blood source, like the female mosquito Anopheles considers humans the primary source of blood today for its mosquito. The flies infested the dinosaurs with an extinct version of malaria called Paleohaemoproteus burmacis .
While malaria has definitely made the dinosaurs ill, Poinar does not believe they could have made the dinosaurs die out. 
There is no hard evidence that dinosaurs had cataracts. The theory was, however, by L.R. Croft in his book The Last Dinosaurs . In fact, he says that the widespread formation of cataracts made dinosaurs extinct.
Croft claimed that these creatures suffered from cataracts when excessive heat and dangerous ultraviolet radiation from the sun caused global warming. The dangerous radiation caused the dinosaurs to develop cataracts that later led to blindness. So many dinosaurs went blind that they were soon extinct after being unable to take care of themselves.
Croft argued that mammals and reptiles were not extinct because they skillfully avoided the sun and hunted in the dark. The dinosaurs, however, continued to roam during the day.
However, many people do not believe dinosaurs are extinct after developing cataracts. By natural selection, the dinosaurs would have developed a protection against the dangerous radiation. Besides, the whole theory seems strange.
But you get that if you see an ophthalmologist like L.R. Croft, why dinosaurs are extinct. 
Osteoarthritis is the most common osteoarthritis affecting humans today. It starts when the slippery cartilage at the ends of the bone slackens and the hard bone joints come into direct contact with each other. This causes friction between the ends of the bones, which soon wear off. At this time, pain occurs.
Researchers have discovered that even the caudipteryx a small flying dinosaur the size of the modern peacock suffered from this disease. In fact, the dinosaur that lived 130 million years ago is the oldest creature known to suffer from osteoarthritis.
Researchers made the discovery by examining the ankle bones of several birds and flying dinosaurs in Chinese museums. They discovered that 3 of the 10 fossils of the caudipteryx had the condition. However, the researchers do not know why the dinosaur was susceptible to the disease. Interestingly, many small modern birds also suffer from osteoarthritis. 
In 1997, researchers exhumed the remains of Lufengosaurus huenei which lived 170-200 million years ago. They found that the ribs of the dinosaur were somewhat abnormal. Some parts were missing, suggesting that he had suffered some injuries before his death. However, the researchers have not really considered the cause of the injuries and kept them only.
Two decades later, the researchers re-examined the fossil and found that the rib injuries caused by the attack of a larger carnivore on the dinosaur tried to eat it. The team could not confirm the identity of the predator. However, it would have been huge considering that the Lufengosaurus huenei was also enormous. It reached a length of 6 meters and weighed almost two tons.
The Lufengosaurus huenei escaped the predator with a terrible rib injury that soon became infected with some deadly bacteria. The bacteria caused the formation of pus in the ribs, resulting in a deadly bone disease called osteomyelitis.
In humans, osteomyelitis is caused by Staphylococcus aureus . However, the researchers did not confirm whether the bacteria also caused bone disease in dinosaurs. Nonetheless, the dinosaur's disease could have caused severe fever, tiredness, and nausea and then death. Some of the bacteria could have entered the brain and accelerate the death of the animal. 
Strangely enough, the dinosaur could have had the condition even if it had not been bitten. The bacterium could otherwise penetrate the body and enter the ribs through its blood.
4 Septic arthritis
The hadrosaur, a herbivorous dinosaur with a duckbill, appeared to be an unfortunate creature suffering from a variety of diseases. In addition to cancer, it also suffered from septic arthritis, a serious condition that could cause joint pain.
Unlike the previously mentioned osteoarthritis, septic arthritis is caused when germs enter the joints through the blood. Septic arthritis can also be introduced directly into the joints during an injury. In both cases it causes severe pain in the joints and sometimes makes them unable to move.
Researchers discovered evidence of septic arthritis in dinosaurs while analyzing the elbow fossil of a hadrosaur. They found three unusual growths on the joints caused by septic arthritis. Scientists could not confirm how the hadrosaur ended with the disease. However, they believe that it was so painful that the animal had difficulty walking. 
3 Intestinal worms
Dinosaurs suffered from several parasitic worms, including tapeworms and trematodes. The researchers do not know how long these tapeworms have become, but they believe they could have reached 30 meters, which is actually small when it comes to dinosaurs. Tapeworms reach a height of over 24 meters in humans.
It is almost impossible to find clues to parasitic worms in dinosaur bones and skin fossils, as the worms probably died and disintegrated after the death of the dinosaur. However, we can determine the types of worms that lived in dinosaurs by analyzing the coprolites (feces) of the dinosaurs. Coprolites sometimes contain worm eggs or cyst samples.
Thus, in 2006, the researchers George Poinar and Arthur Boucot discovered the first evidence of dinosaur worms. The shit belonged to an unknown carnivorous dinosaur that lived somewhere in modern Belgium. The researchers found evidence of trematode and nematode worms and protozoans, which are suspected, Entamoeba . 
2 Tooth decay
The Labidosaurus hamatus (aka the Lipped Lizard) is an extinct creature of which we have probably never heard of it. It was a 1 meter long reptile that lived around the time when the dinosaurs roamed the earth. However, it is popular for other reasons. It is the earliest known creature that has suffered from toothache and tooth decay.
This was discovered several years ago when Robert Reisz of the University of Toronto Mississauga led a research team to scan the lower jaw of a fossilized Labidosaurus hamatus . They found that the creature suffered from severe tooth decay causing many teeth to be lost.
Researchers do not know how the jaw inflamed, though they believe it had something to do with the animal's diet. The Labidosaurus hamatus was an omnivore. However, the main food consisted of plants. Herbivores and omnivores with a predominantly vegetarian diet often have teeth that specialize in chewing.
This was a major disadvantage for the Labidosaurus hamatus . Excessive chewing disintegrated the enamel and released the nerves in the teeth. The nerves were infected with bacteria, causing the damaged tooth to develop an abscess. This caused painful toothache and consequently tooth decay. Tuberculosis and pneumonia
The earliest evidence of lung disease was found in Proneusticosasiacus (19459015), a marine reptile that lived more than 245 million years ago. The researchers made the discovery fossil after performing an X-ray analysis of a Proneusticosasiacus (19459015) . They discovered that some of his ribs were abnormal. Injuries, cancer, fungus and scurvy were initially suspected until the team restricted them to pneumonia and Pott's disease, a deadly form of tuberculosis that commonly affects the bones.
The researchers found that the reptile had been suffering from the infection for months, or even years, until it died. Other scientists say, however, that the fossil actually belonged to a Cymatosaurus a marine reptile closely related to the Proneusticosasiacus . 
Proneusticosasiacus and Cymatosaurus are closely related to another reptile, the Nothosaur. This creature lived and bred ashore, but hunted in the water, just like today's seals. Interestingly, modern seals are most likely to contract tuberculosis.