Shark Cartilage

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The shark has evolved very little in the last 400 million years and bears remarkable similarity to fossils of cartilaginous fish from the Devonian era, commonly known as the "Age of Fishes." Presumably, the ancestors of today's sharks were well-adapted to the warm inland seas blanketing the landscape at that time. In the present time, sharks seem to have reached an evolutionary dead end. They are well enough adapted to their environment and their genetic material is more or less static. As this photograph shows, they never developed a bony structure, and they also seem not to get cancer. (Unit: 9)