Ancient Sharks’ Cannibalistic Behavior May Have Helped Them Become Giants

KEY POINTS

  • Megalodons grew to be up to 50 feet in length
  • The prehistoric sharks were the biggest among the carnivorous or non-planktivorous shark species
  • Researchers say a unique behavior called intrauterine cannibalism may have helped megalodons grow very large

The ancient megalodon sharks’ predatory behavior inside the womb might have helped them achieve their gigantic size, a new study shows. The shark species grew to be up to 50 feet in length before going extinct about 3.6 million years ago.

In a study published in the journal Historical Biology, a team of researchers explained that most sharks give birth through a method known as ovoviviparity, where the embryos develop inside eggs that remain inside the mother’s body until they are ready to be hatched. In some aggressive shark types like lamniform, the early-hatched embryos often eat the unhatched eggs, a behavior called intrauterine cannibalism, the researchers noted. Megalodons belong

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Megalodon was exceptionally large compared with other sharks

Oct. 5 (UPI) — New analysis of body size among the different genera in the shark order Lamniformes suggests the megatooth shark megalodon was exceptionally massive.

Mature megalodon sharks, which swam the oceans between 15 million and 3.6 million years ago, reached lengths of 50 feet.

For as long as scientists have been finding and studying megalodon fossils, they’ve been aware of the shark’s impressive size, but for the new study, published this week in the journal Historical Biology, researchers wanted to better understand how the species’ size compared with maximum sizes of its many relatives.

Megalodon is a member of a group of sharks known as lamniforms. Most extinct lamniform species are known only by their fossilized teeth, but by analyzing the relationship between teeth and body size among present-day non-planktivorous lamniforms, researchers developed an equation for estimating the body sizes of extinct lamniform shark species.

When researchers estimated

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Cannibalism in the womb may have helped make megalodon sharks giants

The largest sharks ever to hunt in Earth’s oceans may have gotten so big thanks to their predatory behavior in the womb, scientists report October 5 in Historical Biology.

The idea emerged from a study that first analyzed the sizes and shapes of modern and ancient shark teeth, using those data to estimate body sizes of the fish. Paleobiologist Kenshu Shimada of DePaul University in Chicago and colleagues focused on an order of sharks called lamniformes, of which only about 15 species still exist today, including fierce, fast great white and mako sharks as well as filter-feeding basking sharks (SN: 8/2/18).

Well over 200 lamniform species existed in the past, some of them quite large, Shimada says. But none is thought to have rivaled Otodus megalodon, commonly called megalodon, which lived between about 23 million and 2.5 million years ago. Determining just how giant these creatures were

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