英语时差:恐龙也会得癌症？
Dinosaur Cancer If you think that cancer is only found in humans, or that it’s a modern disease, think again. Scientists have not only found cancer in many other animals, they have found it in dinosaurs that lived more than sixty-five million years ago. Wondering if fossils could tell us something about ancient cancer, scientists traveling with a portable x-ray machine scanned ten-thousand dinosaur vertebrae of over seven-hundred museum specimens. These included many popular dinosaurs such as Stegosaurus, Triceratops and Tyrannosaurus. Much to their surprise, they found that only one group suffered from cancer-the hadrosaurs, or “duck-billed” dinosaurs. Twenty-nine benign tumors were found in the tail bones of ninety-seven animals. These were mostly hemangiomas or tumors of the blood vessels. Doctors find the same type of tumors in humans today. One Edmontosaurus also had a malignant tumor. Why did duck-Billed dinosaurs have cancer and not the others? Scientists aren’t sure. They thought that if hadrosaurs were long-lived, they would have a greater chance of developing cancer, but they lived relatively short lives. These twenty-five foot long herbivores needed plenty to eat, so diet was another thing scientists considered. Maybe conifers were to blame. Hadrosaurs ate plenty of them and they did contain known carcinogens. The trouble is, other conifer eaters didn’t exhibit the same cancer. The cause of hadrosaur cancer remains a mystery today, but dinosaur fossils are helping unlock secrets of diseases millions of years old. Who knows what else they’ll reveal.
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