Though Mullaly, who is a schoolteacher and amateur fossil hunter, has collected more than 100 fossils, he never before found a prehistoric shark tooth.
Speaking after he made the discovery, Mr. Mullaly said: "I was immediately excited, it was just flawless and I knew it was an important find that needed to be shared with people".
"These teeth are of global significance, as they represent one of just three associated groupings of Carcharocles angustidens teeth in the world, and the very first set to ever be discovered in Australia", said Dr. Erich Fitzgerald, senior curator of vertebrate paleontology at Museums Victoria.
The museum has released its study of the finds this week, and it has confirmed that these are from a great jagged narrow-toothed shark, or Carcharocles angustidens, a 30-foot shark that patrolled the waters off of Australia 25 million years ago.
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Researchers believe those teeth were left behind as a result of getting lodged in the carcass of the Great Jagged Narrow-Toothed Shark as smaller sharks fed on it after the much larger animal died.
A prehistoric shark feast the Carcharocles angustidens being feasted upon by several Six Gill Sharks. That cartilage does not easily decompose, which is why individual shark tooth fossils are somewhat common. According to Fitzgerald, the vast majority of shark dental remains consist of single fossilized teeth.
He explained that nearly all fossils of sharks worldwide were just single teeth, and it was extremely rare to find multiple associated teeth from the same shark.
In the video below, Fitzgerald comments on the importance of this discovery and the contribution that citizen scientists like Mullaly bring to paleontology. These belong not only to Carcharocles angustidens, but also to much smaller species, the sixgill shark (Hexanchus), the scavenger that has survived until today.
"This find suggests they have performed that lifestyle here for tens of millions of years", Museums Victoria paleontologist Tim Ziegler said.