What was the life span of enormous megalodon sharks?

By Dr. Rowland, Paleontologist & Las Vegas Natural History Lab Manager

Megalodons (technically Otodus megalodon) are an extinct species of school-bus-size sharks that lived between about 23 million years ago and 4 million years ago (Miocene Epoch). Their enormous size makes them one of the largest carnivores that ever lived on Earth.

Because the skeletons of sharks are made of cartilage rather than bone, the skeletons almost never get preserved as fossils. Only the enamel-coated teeth are usually found, as shown in the first photo. The large size of these ancient sharks has been estimated, based on the size of the teeth. The second photo shows a reconstructed megalodon jaw, compared to the smaller (but still impressively large) jaw of a great white shark, on display at the Las Vegas Natural History Museum.

In a new study, published in the peer-reviewed journal Historical Biology, paleontologists examined the only known, fossilized vertebral column of a megalodon. They discovered that the vertebrae contain concentric growth rings, analogous to tree rings. The shark apparently laid down a new layer of bone tissue each year, which allowed the researchers to determine its age. It was 46 years old when it died. They estimate its length to have been 30 feet. Some megalodons are estimated to have been much larger―as long as 50 feet. Using the data from this study, together with previous research, the researchers concluded that the potential lifespan of megalodons was 88-100 years.

Megalodons were over six feet long when they were born. It was apparently a reproductive strategy for the first-born shark to eat the unhatched eggs of its siblings, within the mother’s uterus, thereby getting a nutritious, prenatal jump in life. This characteristic behavior is also present in great white sharks and other living relatives of megalodons.