Massive sharks used to dominate the seas — what led these great, dangerous sharks to die off about 2.6 million years ago? Competition for food and prey scarcity just might be the reason, according to a new study.

Carcharocles megalodon — the largest shark that ever swam Earth’s waters, reaching up to 59 feet long and likely feeding on marine mammals — was previously believed to have become extinct due to changes in climate.

University of Zurich researchers, who studied the megalodon shark’s geographical distribution over time, now argued that the behemoth animal probably disappeared due to the decreased diversity of its prey and intensified competition in the form of new predators.

“We were not able to ascertain any direct link between the extinction of C. megalodon and the global fluctuations in temperatures during this time,” reports researcher Catalina Pimiento of the Paleontological Institute and Museum of Zurich, Switzerland.

Changing climate, including colder periods and rising water temperatures, did not appear to influence the giant sharks’ range and population density.

Instead, the assessment of about 200 megalodon shark records from museums — ranging over 20 million years in age — instead revealed that their food resources disappeared.

The team took a close look at the evolution of other species that lived around the time of the monster sharks, finding intense competition for rapidly dwindling food sources. Numerous smaller marine mammals went extinct when megalodon range shrank, and new predators such as the predecessors of the great white shark came into the scene.

Based on the researchers’ reconstruction of the prehistoric creature’s range and abundance through time, the sharks were mainly seen in the Northern Hemisphere’s warm waters in the early Miocene period, up to about 16 million years ago. They later went further into the South American, Asian, and Australian coasts.

They peaked in numbers in the middle Miocene, while they occupied the widest geographical span in the late Miocene. Their steady decline was traced back to about five million years ago, around the time of the advent of a glacial era during the Pliocene age.

The findings were published in the Journal of Biogeography.

In October last year, prehistoric shark teeth from the “Meg” began washing up on North Carolina shores because of high tides and recent storms. Some of these teeth were the size of an adult hand — since every inch of shark tooth is equivalent to 10 feet of its body, the teeth’s owner was probably about 60 feet long.

Megalodon shark teeth were estimated to be three times stronger than those of the T-rex dinosaur — just some of the fascinating details that humans know of these great predators that once reigned supreme on the planet.

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