20-Foot 'Gigantic Shark' Fossil Found in Duck Creek Formation of Texas

A fossilized gigantic shark was found in Texas. At over 20 feet long, it is one of the largest sharks to have swam the seas. Janessa A. Doucette-Frederickson/PLOS One Journal

In 2009, Janessa A. Doucette-Frederickson tripped over what she thought was a rock while exploring a dig in the Duck Creek Formation of Texas. When she later examined it with co-researcher Joseph Frederickson, who was then her boyfriend and is now her husband, they realized it was in fact a giant fossil, and a most unusual one at that. Along with their fellow paleontology club and research group members, they discovered Doucette-Frederickson had actually stumbled over the vertebrae of a giant, ancient shark.

Based on the size of the vertebrae, the scientists determined that the shark was about 20 to 22 feet long. In their research findings, published by PLOS One Journal, they dubbed it a "gigantic shark."

"We thought it was a really large fossil and we all came together and dug it out," explained Frederickson in a phone interview. "We realized it was a really large shark." At first, the discovery went unstudied, as sharks were not part of Frederickson's background and experts were not sure about the discovery's context. After he became a doctoral student at the University of Oklahoma, Frederickson felt confident he could study the fossils successfully.

One of the shark vertebrae fossils as it was discovered during a dig in the Duck Creek Formation of Texas. Courtesy of Joseph A. Frederickson

He said he donated the fossils to the Oklahoma Museum of Natural History, and so they became part of the public trust and could be worked on. "They were really cool...and really big," he said. "I looked through the literature and realized there was another really large shark, of which only one vertebrae had been found, and it was from Kansas."

The Kansas shark's remains were in far worse condition than Frederickson's, but they allowed him to question whether there had lived a community of massive sharks in the region millions of years ago" "We came to the conclusion that these two animals are probably the same type of very large shark, but it begged the question what species did it belong to?"

Fossil sharks are named and identified based on teeth, which were not found with either vertebrae. Without the teeth, Fredrickson and his research partners were unable to pin down the exact species of shark. Based on the vertebrae found, though, they did make the discovery that this shark was likely a large body lamniform.

shark vertebrae
Additional shark vertebrae found in Texas by the researchers. Joseph A. Frederickson/PLOS One Journal

Though its size is closer to that of a great white, this ancient shark is a nearer relative to the sand tiger and goblin sharks, Frederickson explained. "Goblin sharks and sand tiger sharks don't get to the size that we are seeing with this fossil," he said. "That's the interesting thing--this is one of the biggest sharks that ever lived, one of the two or three biggest to swim in the ocean ever."

Frederickson hypothesized that the Texas and Kansas sharks may have been cases of gigantism. "It is quite likely that that happens but we aren't really sure," he said. "The next thing we want to do is look at how they grew up."

Though research is ongoing as to how old the shark was when it died and how it lived, Frederickson is confident that the giant shark "quite possibly would've eaten just about anything. At 20 feet, there isn't much it couldn't eat."