In search of a snack Alberto Gennari

With a jaw up to 3 metres wide that had the power to crush a small car, megalodon had a formidable bite.

But it seems the largest shark to ever live preferred to snack on amuse bouche rather than more substantial prey – and that could have been its downfall.

The 16-metre-long Carcharocles megalodon is thought to have prowled the world’s oceans for around 14 million years before dying out about 2.6 million years ago.


Analysis of the fossils of marine mammals that lived in the oceans around 7 million years ago have provided the most detailed insight yet into the kind of prey it targeted. Distinctive scrape marks and wounds left on bones by the shark’s huge, serrated teeth suggest it preferred hunting now-extinct dwarf whales and seals.

“The disappearance of the last giant-toothed shark could have been triggered by the decline and fall of several dynasties of small to medium-sized baleen whales in favour of modern, gigantic baleen whales,” says Alberto Collareta, a palaeontologist at the University of Pisa in Italy and lead author of the study.

Cooling climate

The researchers believe a cooling climate, which caused a fall in sea levels as water was locked up in the polar ice caps and glaciers, led to rapid changes in the coastal environments where smaller baleen whales lived. This caused numbers of these smaller whales to fall while the changes favoured larger open-ocean whales that were too large for megalodon to tackle.

The changing climate also brought seasonal food booms around the poles, which helped drive the evolution of larger whales – like the giant humpback and blue whales of today – capable of making the long-distance migrations needed to feed there. It is possible megalodon, more used to a warmer coastal habitat, was unable to follow them to the colder waters.

Collareta and colleagues examined wounds left on fossils found in the Pisco fossil beds in Aguada de Lomas, Peru.

Among those carrying marks left by megalodon teeth were the jawbone of a diminutive, extinct species of baleen whale called Piscobalaena nana and an early type of seal called Piscophoca pacifica. Both animals grew to less than 5 metres in length – under a third the size of megalodon.

But Dana Ehret, curator of palaeontology at the Alabama Museum of Natural History, believes megalodon may also have targeted larger whales from time to time.

Big meal

“I’ve seen a specimen from Virginia yet to be published of a fairly large baleen whale found with a megalodon tooth lying on top of an indentation in the bone,” he says.

But he adds it is unclear if the whale was alive or dead when the shark pounced. “It could have been scavenging on the whales like modern white sharks do today,” Ehret says.

Some modern sharks, however, have been seen actively targeting giant whales like humpbacks.

Catalina Pimiento Hernandez, a palaeontologist at the University of Zurich, Switzerland, says megalodon dietary preferences may have changed during their lifetime and depended on the area they inhabited. “More work is needed to be sure that megalodon globally preferred small prey rather than big,” she says.

Research published last year suggested that competition from white sharks, which were evolving around this time, and killer whales may have also pushed megalodon to extinction.

Journal reference: Palaeogeography, Palaeoclimatology, Palaeoecology, DOI: 10.1016/j.palaeo.2017.01.001

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