Scientists in Australia have found a jaw full of ancient mega-shark teeth, a rare evidence that sharks twice the size of a Great White once stalked waters Down Under, researchers said Wednesday.

Palaeontologists at Museums Victoria, with the help of a local fossils enthusiast, uncovered the fossilized teeth set belonging to the prehistoric Great Jagged Narrow-Toothed Shark (Carcharocles angustidens) in a boulder at Jan Juc in Victoria, 100 kilometers south of Melbourne.

They also found teeth from several Sixgill sharks, which the scientists said feasted upon the giant shark after it died.

The fossil, consisting of 40 teeth, is the first of its kind found in Australia. The set of giant shark teeth, up to 7 centimeters long, is "one of just three associated groupings in the world."

The mega-toothed shark, which lived about 25 million years ago, were the top predator, preying on small whales. They could grow to be more than 9-meters long, almost twice the size of the Great White.

The museum said finding multiple teeth from the same shark are extremely rare.

Tim Ziegler, a palaeontologist at Museums Victoria, said the Sixgill shark's teeth would have become dislodged from their jaws as they fed on the huge carcass of the mega shark.

"Sixgill sharks still live off the Victorian coast today, where they live off the remains of whales and other animals," he said.

"This find suggests they have performed that lifestyle here for tens of millions of years."