Head of Giant 330-Million-Year-Old Shark Found in Wall of Kentucky Cave

Researchers have uncovered the remnants of a huge, fossilized shark head in the walls of a cave in Kentucky.

The remains of the ancient animal are located in Mammoth Cave National Park, which is home to the longest known cave system on Earth—one that extends for more than 400 miles, according to the National Park Service.

The shark fossil—dated to around 330 million years ago—was first spotted alongside several others by Rick Olson and Rick Toomey, two Mammoth Cave experts who were conducting investigations of the area, the Louisville Courier Journal reported.

The pair took photos of the fossils and sent them to Vincent Santucci, a paleontologist with the National Park Service, in the hope he could identify them.

Santucci also passed the images on to John-Paul Hodnett, a paleontologist at Dinosaur Park in Maryland. This site contains rare fossil deposits from around 115 million years ago.

Hodnett was able to identify most of the shark fossils in the images, however, he became particularly interested in one set of remains.

"One set of photos showed a number of shark teeth associated with large sections of fossilized cartilage, suggesting there might be a shark skeleton preserved in the cave," Hodnett told the Journal.

Shark skeletons are made of cartilage, which does not fossilize as well as bone so is rarely preserved. Shark teeth fossils, on the other hand, are commonly found all over the world.

After reviewing the images, Hodnett decided to visit the park and examine the fossils for himself. "I wasn't exactly sure what I was going to see in the cave during my trip in November," he told the Journal. "When we got to our target specimen my mind was blown."

While the palaeontologist was not able to uncover a full skeleton, he did identify a skull, lower jaw, cartilage and several extremely-detailed teeth. Given the dimensions of these remains, Hodnett estimates that the shark was about the size of a modern day great white, which grow to an average of around 15 feet, according to National Geographic.

He said the remains likely belong to a species known as Saivodus striatus which lived between 340 and 330 million years ago during the Late Mississippian geological period.

For much of the Mississippian period, which lasted between 359 to 323 million years ago, the area that is now Kentucky was submerged beneath shallow tropical seas. As a result, many marine fossils are found in the area.

The latest discovery was made as part of the Mammoth Cave National Park Fossil Shark Research Project, which so far has identified around 100 individual specimens in the cave system.

"We've just scratched the surface," Hodnett said. "But already it's showing that Mammoth Cave has a rich fossil shark record."

The latest find is not the only prehistoric shark to have been recently discovered in the United States. In November, researchers announced that they had identified an entirely new species of shark in Kansas, which lived around 91 million years ago.

According to a study published in the Journal of Vertebrate Paleontology, the shark could have measured around 17 feet in length.