Megalodon were happy with their size

Carcharocles megalodon is the largest shark to have ever existed. Scientists Catalina Pimiento and Meghan A. Balk wanted to find out whether its size changed over its 14 million year history.

They searched through museums around the world to collect data on Megalodon tooth fossils. Then, they worked out the body length of each tooth’s original owner by noting where the tooth sat in the shark’s mouth. To assist this process the scientists also looked at tooth position and body length in modern great white sharks.

Pimiento and Balk wanted to test the hypothesis that Carcharocles megalodon grew steadily larger over the course of its long history. They wanted to find out whether the megalodon was at its largest size just before its extinction.

The scientists found that the hypothesis was false. The megalodon’s body length held steady, in the region of 10.54 metres, over millions of years. This suggests that this was the shark’s optimum size and that there was no advantage to it growing any bigger.

There were, however, variations in size across the world. Southern Hemisphere sharks were generally larger than Northern Hemisphere sharks. Megalodon in the Pacific tended to be bigger than megalodon in the Atlantic.

Pimiento and Balk advise that these differences could be due to nature or could be due to collectors’ preference for larger teeth.

If the size variations are natural, they say, it’s likely to be because of differences in the sharks’ environments. Availability of food, water depth and ocean currents could have an impact on size.

Although megalodon was a global animal, individual populations may have kept apart from each other. And through breeding it may have occurred that some populations were bigger than others.

For more information about this fascinating study, read Pimiento and Balk’s article “Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators.”

The picture below shows a Great White Shark. To see what the Meg might have looked like, visit the Natural History Museum’s information page.