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Sharks

Prehistoric Shark with Enormous Mouth Discovered

posted: 09/11/15
by: Jennifer Viegas for Discovery News

A new large-mouthed shark dating to nearly 100 million years ago during the Dinosaur Age has just been identified.

The shark, Pseudomegachasma, lived in warm oceans and used its gigantic mouth to feast on thousands of tiny creatures, such as small crustaceans and bits of algae, collectively known as plankton. The shark will be described in the upcoming issue of the Journal of Vertebrate Paleontology.

Lead author Kenshu Shimada of DePaul University told Discovery News that "this extinct plankton-eating shark could have looked like a sand tiger shark with a large mouth equipped with many tiny teeth."

Pseudomegachasma
Kenshu Shimada

Modern sand tiger sharks are known for their protruding teeth, small eyes and pointy snouts, which give them a menacing look. These existent sharks, classified as "vulnerable" by IUCN Red List of endangered animals, pose little threat to humans, however.

An extremely rare species of modern deepwater shark, the megamouth, also has a connection to the Dino-Era big-mouthed beast.

"The fossil shark," Shimada explained, "has a tooth design that is nearly identical to the living megamouth shark, hence the new genus name Pseudomegachasma."

Shimada and his team made the determinations after analyzing recently collected tiny fossil teeth from Cretaceous rocks. The scientists believe that at least two species fall under the new Pseudomegachasma lineage: <em from Russia and Pseudomegachasma comanchensis from the United States

The fossil record suggests that representatives of the newly identified shark lineage first emerged in a shallow-water environment in Russia before later migrating to the North American Western Interior Seaway that once split North America into two land masses.

The prehistoric sharks already have at least one claim to scientific fame.

Pseudomegachasma (collectively referring to the species falling under that genus) appears to be the oldest known plankton-feeding shark in the fossil record that evolved independent of the four known lineages of modern-day plankton-feasting cartilaginous fish: the megamouth sharks, basking sharks, whale sharks, and manta rays.

So the evolutionary history of plankton-feeding sharks may have been much more complex than previously thought. It's now known that from very early on, sharks were taking advantage of plentiful plankton.

To give some idea on how long ago that was, consider that Pseudomegachasma was thriving in ocean waters around 85 million years before infamous Megalodon -- the world's largest ever shark -- is believed to have lived.

This post originally appeared on Discovery News

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