Sharks lost some of their mystique with the recent finding that they've undergone more evolutionary adaptations than previously believed, the Guardian reported.

Before the study, titled "A Palaeozoic shark with osteichthyan-like branchial arches," was published on Wednesday, scientists believed sharks had changed little since their emergence over 400 million years ago (well before dinosaurs). Sharks were credited possessing a more ancient gill structure than modern fish.

Researchers, however, disproved the notion of sharks as "living fossils" by studying a recently discovered, 325 million year old fossil of an ancestor known as chondrichthyans (also an ancestors to rays). The fossil, the oldest chondrichthyan on record, projected a small creature with tiny, but sharp teeth. It also had a gill structure (from which a more complex jaw structure would evolve) more closely resembling modern fish than modern sharks, suggesting that some time after 325 million years ago, shark's acquired their current form.

The finding also suggests that other types of fish have more ancient gill structures. Thus, scientists should study another species of fish -- specifically bony fish -- in order to better understand the evolutionary arc of sea creatures.

"We're throwing down the gauntlet," study co-author John G. Maisey, a vertebrate paleontologist at the AMNH, told National Geographic. "This is the real condition in an early shark, and it changes how we have to think about the evolution of jawed vertebrates."

Because ancient shark and/or ancestors of shark fossils are so rare, the study wasn't able to corroborate its findings with other specimens to further justify its conclusions. Still, the fossil evidence from the one chondrichtyan fossil is strong enough to change the reputations of sharks as a living fossil.

"The ultimate conclusions [to this study] could very well change a bit, but I think the general picture's solid," said Martin Brazeau, a paleontologist at Imperial College London who was not part of the study.