Marine Cozzolino
Cancers are not new diseases.
They have been around for millions of years,being a life threatening nuisance to even the great animals of the Mesozoic era. This perticular study of dinosaurs has shown that they too can develop cancers.
A 2003 study seeks to learn more about the occurrence of these tumors in animals dating back millions of years. Apparently cancers picked and chose and in this study, researchers have come to the conclusion that dinosaurs were not all equal when it came to the disease. By examining more than 10,000 vertebrae fossils belonging to 700 individuals by fluoroscopy, an imaging technique, they sought to define which dinosaurs were more cancer prone.
The unlucky ones in this study are the Hadrosaurids. These are herbivorous, duck-billed dinosaurs that were found in North America, Asia and Europe during the Cretaceous period, some 100 million years ago. At that time the earth was also populated by ankylosaurs, pachycephalosaurus, triceratops, and T-rex. But among the parade of dinosaurs observable at that time, the Hadrosauridae were quite clearly more at risk of having cancer than any other dinosaurs. The caudal vertebrae of many members of this family were attacked by the disease, while the number of tumors in other dinosaurs studied (such as stegosaurids, ankylosaurs, sauropods, theropods) remained very low.
As in present-day humans, the reasons for these tumors are controversial. Apart from the obvious ‘why aren’t the dinosaurs here and the cancers extinct?’, an interesting question is why only a specific family of dinosaurs is subjected to this pathology. One of the proposed culprits is their diet. Rare fossil stomach remains have shown that Hadrosaurs fed on conifers making them the only dinosaurs to ingest them. Another clue is the physiology of Hadrosaurs, which had a different bone structure that is not found in most dinosaurs.
Studies of cancers in Cretaceous dinosaurs are useful in understanding how dinosaurs became extinct. Indeed, some hypotheses assume that the extinction of the dinosaurs was partly due to a cosmic ray flux, which irradiated everything on earth every 62.3 million years. A good way to test this hypothesis is to compare the number of cancers between the dinosaurs of that time and the present vertebrates: radiation causing cancers, if the hypothesis is true, then the dinosaurs of the Cretaceous had more cancers than today. But when comparing the rate of cancer between dinosaurs and modern vertebrates, the researchers observed no significant difference, which invalidates the hypothesis of cosmic radiation. There’s something to worry about in 60 million years!
