Great white sharks may have helped bring megalodones to extinction

For millions of years, megalodon sharks were the main ocean predators, and then great white ones appeared. A new analysis of teeth hints that competition from great white sharks for food may have helped mega-tooth giants get an extra boost to extinction.

Scientists have reconstructed shark eating habits by analyzing zinc in the teeth of 20 living shark species and 13 extinct species, including megalodon (Otodus megalodon). Megaladons and big whites occupied a similar ecological nichedevouring marine mammals such as whales and seals, researchers said on May 31 in The nature of communication.

O. megalodon was one of the largest carnivores ever lived to which they grew up at least 14 meters long (CH: 12.01.21). This giant began threatening the oceans about 23 million years ago. It is unclear when and why he died. The species may have survived to about 2.6 million years ago. Or maybe it disappeared another 3.5 million years agoabout the time the great white shark Carcharodon carcharias appeared.

To find out if two sharks ate similar food, the researchers turned to zinc, which has two main forms: zinc-66 and zinc-64. The relative amount of these isotopes stored in tooth enamel may indicate the position of the animal in the food web. Plants – and herbivores – have a relatively high content of zinc-66. Up in the food chain this ratio of 66 to 64 decreases.

The analysis showed when and where O. megalodon and C. carcharias overlapped, sharks had a similar ratio. This discovery suggests that their diets also coincide, say geoscientist Jeremy McCormack of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues.

However, the fact that sharks consumed similar prey is not evidence that they were in competition, the researchers say. And there are many factors that may have contributed to the extinction of megalodones (CH: 08/10/18). These factors include changes in ocean circulation, falling prey populations, and competition for food with other oceanic creatures such as killer whales.

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