Sharks have swum in the oceans for almost 450 years. But longevity is only part of the story. That extra few million years of evolution have enabled many shark species to develop some extraordinary abilities as perfect predators.

Is 450 million years a long time in evolution? Life is thought to have begun on earth about 3.8 billion years ago. Life on earth began as bacteria and did not advance beyond the one-celled format until around 580 million years ago. The first fish appeared around 510 million years ago. These were armored jawless fishes known as ostracoderms. And then came the sharks either 455 or 425 million years ago—there is some disagreement among paleontologists as to when.

Many of us tend to think of dinosaurs as dominating the prehistoric world. But dinosaurs didn’t appear until about 230 million years ago. Mammals first appeared around that same time. The first human-like animal, or hominid, dates to about 4.5 million years ago, but modern humans only date back perhaps 60,000 years. And recorded civilization has lasted only about 5,000 years. That means sharks have existed 100 times longer than hominids and 3 times longer than dinosaurs (or twice as long as dinosaurs if we include birds).

Shark fossil evidence

Paleontologists piece together the history of ancient living things, largely through the discovery and analysis of fossils. Fossils are the mineralized or otherwise preserved bodies or impressions of living things.

Problem is, sharks generally don’t fossilize as well as other animals because their skeletons are made of cartilage, a softer and more flexible tissue. Cartilage isn’t as easily fossilized as is bone.

Fortunately, shark teeth do fossilize well, and sharks produce thousands of teeth in a lifetime. Fossilized shark skin scales and, over time, other body parts have also been found. Much of the earliest shark evolution and history is known through fossils of teeth and scales that are unique to sharks. Paleontologists are able to find enough clues in a well-preserved fossil to determine much about a shark, including its species, and clues to suggest size and behavior.

The oldest fossilized evidence of prehistoric sharks comes from shark-like scales that date to 455 million years ago during the Ordovician Period, in Colorado. Some paleontologists do not agree that these scales are sufficiently shark-like to pronounce them sharks. But there is no disagreement that scales found during the Silurian Period, aged 420 million years, are from sharks. Shark scales from this period have been found in Siberia and Mongolia. The oldest shark teeth are from the Devonian Period, about 400 million years old, found in Europe. Nothing beyond these scales or the teeth is known about these early sharks.