Sharks appear to have evolved from fish between 400 and 450 million years ago, during the Early Devonian period. The earliest known sharks were fairly small and measured just 12 to 16 inches long. They appear to have lived near or on what is now Antarctica.

By 360 million years ago at the beginning of the Carboniferous period, there were many species of sharks, some of which were quite similar to modern sharks. At the end of the Permian period, about 245 million years ago, many shark species were wiped out in a massive global extinction event. Modern sharks began to appear at the beginning of the Jurassic period, about 213 million years ago, and have lived in the oceans ever since.