
Mullaly was walking along Jan Juc, a renowned fossil site along Victoria's Surf Coast in south Australia, when he spotted a partially exposed shark tooth in the rock.
"I was immediately excited, it was just perfect," Mullaly said.
That was just one of multiple teeth Mullaly found that day in 2015. Three years later, scientists have confirmed his hunch, saying Thursday that the teeth are all about 25 million years old and belonged to an extinct species of mega-toothed shark -- the Great Jagged Narrow-Toothed Shark (Carcharocles angustidens).
The ancient shark was believed to grow up to about 9 meters (30 feet) long, double the size of a great white shark. The teeth discovered on the beach were around 7 cm (2.75 inches) in length.
Mullaly's is one of the rarest finds in the history of paleontology, according to Erich Fitzgerald, a palaeontologist at Museums Victoria who led a team to excavate the site where the initial fossils were found.
"If you think about how long we've been looking for fossils around the world as a civilization -- which is maybe 200 years -- in (that time) we have found just three (sets of) fossils of this kind on the entire planet, and this most recent find from Australia is one of those three," Fitzgerald told CNN.
'My jaw sort of dropped'
Fitzgerald said he was first contacted by Mullaly last year about a different discovery, during which he briefly mentioned the find at Jan Juc, but it wasn't until the amateur fossil hunter brought the teeth into the museum that Fitzgerald realized how significant the discovery was.
Sharks have the ability to regrow teeth, and can lose up to a tooth a day. That cartilage does not easily decompose, which is why individual shark tooth fossils are somewhat common. However, Fitzgerald said that finding multiple teeth from a single shark is extremely rare.
"That doesn't happen. That just doesn't happen. That's only happened once before in Australia, and that was a totally different species of shark," he said.
When Mullaly told him the boulder he found was still on the beach, Fitzgerald said "my jaw sort of dropped."











