The shark named Megalodon is the largest marine predator that ever existed.
The deposit was found at the foot of an undersea mountain 2,000 metres (6,500 feet) deep during an ocean research campaign, the institute said Monday.
Those responsible for the discovery call this "an event of great scientific significance".
These fossils "show that the biggest marine predator of all time lived, hunted and reproduced in these waters during that era". The shark grew to 20 metres (65 feet) long and weighed 100 tons.
For the kind of teeth it possessed, scientists think it fed on large prey like whales, dolphins, seals and other marine mammals, as well as on large fish and turtles.
It was a great migrator found in every ocean, according to the institute.