‘Megajaws’ kept blue whale small

Natural historian Enya Kim stands inside a fossilised megalodon jaw. Source : AFP

October 23th, 2014 (John Ross). SCIENTISTS have pinpointed the event that allowed the world’s biggest living creature to emerge — the demise of the world’s biggest ever shark.

The bus-sized “Carcharocles megalodon”, an 18-metre behemoth that feasted on marine mammals, is one of the most celebrated monsters of the deep. About four times as big as a great white, it evolved around 15 million years ago.

Scores of fossils and toothy reconstructions make megalodon a museum favourite. But despite its popularity and widespread fossil record, little has been known about its extinction.

Now an analysis of 42 of the most recent fossils has found the monster disappeared 2.6 million years ago — just before the filter-feeding baleen whales became giants.

The finding, and the fact that fossils of baleen whales are often found with megalodon teeth, suggests that the monster’s diet included the ancestors of humpbacks, southern rights and even blue whales, considered the heaviest creature ever.

Announcing the finding this morning in the journal PLoS ONE, the team says more research is needed to be sure that megalodon ate baleen whales. But it was only after megalodon’s extinction that baleen whales reached their “modern gigantic sizes”, the paper says.

Lead author Catalina Pimiento, of the University of Florida, said it was not clear what had killed off megalodon. “That will be the subject of my next project,” she said.

Citation: When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record. Pimiento C, Clements CF (2014). PLoS ONE 9(10): e111086. doi:10.1371/journal.pone.0111086

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