In 2015 Philip Mullaly was strolling along a beach in Victoria, Australia, when he spotted what looked like a shining serrated blade stuck in a boulder. Using his car keys, Mr. Mullaly carefully pried from the rock a shark tooth about the size of his palm. He didn’t know it at the time, but the tooth he uncovered once belonged in the mouth of a 25-million-year-old giant shark that was twice the size of a great white.
“It was an awesome creature, it would have been terrifying to come across,” Mr. Mullaly said.
Though Mr. Mullaly, who is a schoolteacher and amateur fossil hunter, has collected more than a hundred fossils, he never before found a prehistoric shark tooth. He returned to the boulder a few weeks later and to his surprise dug up several more three-inch teeth.
“It dawned on me when I found the second, third and fourth tooth that this was a really big deal,” said Mr. Mullaly.
He contacted Erich Fitzgerald, a paleontologist at the Museums Victoria in Melbourne, which announced the find on Thursday. Dr. Fitzgerald identified the teeth as belonging to a type of mega-toothed shark called the great jagged narrow toothed-shark, or Carcharocles angustidens.
“Angustidens was a bloody big shark, we’re talking more than 30 feet long,” said Dr. Fitzgerald.
Dr. Fitzgerald also determined that all of the teeth most likely came from the same individual shark. Though people have found single shark teeth belonging to the mega-toothed shark before, Mr. Mullaly’s find was the first time a set had been discovered in Australia, and only the third time a set of teeth belonging to the same individual Carcharocles angustidens had been found in the world.
“I said to him, ‘You realize how important and rare these are?’” Dr. Fitzgerald said. “‘There could be more there. We need to go back down there and dig.’”
So with a team of paleontologists, Dr. Fitzgerald and Mr. Mullaly returned to the beach last year, which was south of Melbourne. When the tide was low enough, the team uncovered more than 40 shark teeth from the boulder and part of the giant shark’s vertebrae. Dr. Fitzgerald said that each Carcharocles angustidens tooth they found came from a different spot in the shark’s jaw, which meant that all of the teeth most likely came from the same individual mega-shark.
“The teeth were finely serrated and sharper than a steak knife,” said Dr. Fitzgerald. “They are still sharp, even 25 million years later.”
Mr. Mullaly donated the teeth to the Melbourne Museum, where they are on display until Oct. 7.
Among the treasure trove of mega-shark teeth, the team also found prehistoric teeth belonging to a sixgill shark, which is a bottom-feeding scavenger that swims off the coasts of Australia today. Although the team found evidence that there was only one mega-shark there, they found indications that there were several different sixgill sharks on the scene. The findings paint a gruesome picture of what the paleontologists think occurred at this spot.
Though it was the fiercest predator in the sea during its time, this colossal shark must have died and sunk to the seabed. There, a school of sixgill sharks, each with saw-like teeth, sliced its rotting flesh apart and feasted upon its carcass.
“It’s shark eating shark,” Dr. Fitzgerald said.