About 100 million years ago, a gigantic shark the size of a two-story building swam in shallow seas that covered Texas and Oklahoma, a new fossil discovery indicates.

The Leptostyrax macrorhiza would have been one of the largest predators of its day, said study co-author Joseph Frederickson, a doctoral candidate in ecology and evolutionary biology at the University of Oklahoma, according to Live Science. The marine reptiles previously believed to be the top of the food chain during that time were probably appetizers for the shark.

"Jaws from the movie was 24 feet long so this thing would have been about the same size," Frederickson told Oklahoma's News 6.

While he was an undergraduate student at the University of Wisconsin-Milwaukee, Frederickson had started an amateur paleontology club. In 2009, the club took a trip to the Duck Creek Formation, outside Fort Worth, Texas. About 100 million years ago, that area was part of the Western Interior Seaway that split North America.

The discovery was "completely on accident, serendipity," Frederickson joked with News 6. Janessa Doucette-Frederickson, Frederickson's then-girlfriend (now wife) and University of Oklahoma anthropology doctoral candidate, tripped over a boulder and saw a large vertebra. The team dug out three vertebrae, each about 4.5 inches (11.4 centimeters) in diameter.

"You can hold one in your hand," Frederickson told Live Science, but that's all that your hand can fit.

This discovery changes the picture of the Early Cretaceous seas, and Frederickson said he is excited to be a part of it.

"I'm one of the few people who have actually seen a shark this size, I've seen these fossils, and now I get to share it with everybody," he told News 6.