'Monster' 30-foot ancient crocodile discovered by scientists (video)

Today's crocodiles may seem fearsome but an even bigger and predatory version of the animal is believed to have lived on earth about 130 million years ago.

A new study documents the discovery of this previously unknown creature which thus far is the largest of its kind in the world.

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Based on recovered remains found in Tunisia, researchers have determined that the prehistoric croc is likely to have weighed around three tonnes and had a length of more than 30 feet.

With a skull measuring five feet long the lead author has been quoted as saying: "This is an incredibly big crocodile, it is twice as big as a present day marine crocodile."

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Aside from the size differential it's believed that the animal resembled its smaller, modern counterpart in most other ways, but its snout was likely more narrow for better swimming.

The researchers believe this discovery calls into question widely held views about the mass extinction because the species was considered wiped out 20 million years prior to the date of the current specimen.

According to National Geographic, scientists have called the species 'Machimosaurus rex' and the fossils were discovered by Federico Fanti from the University of Bologna along with the support of the National Geographic Society.

The find included a skull and some other bones.