The fossilized remains of a "gigantic shark" – the size of a two-story building and over 100 million years old – has been unearthed in Texas.

The colossal Leptostyrax macrorhiza is believed to be among the biggest predators of its time. It could alter theories on the evolution of massive predatory sharks, and push back estimates of the time they tore through the seas.

The fossilized remains were found by researchers near Fort Worth, Texas — by accident.

Accidental Discovery

How did the researchers chance upon the fossilized remains of the gigantic shark? In 2009, study co-author Joseph Frederickson went to the Duck Creek Formation on the outskirts of Fort Worth as part of an amateur paleontology club trip. The area is well known for a slew of invertebrate marine fossils such as ammonite, and is believed to have been a part of the Western Interior Seaway nearly 100 million years ago.

While taking a tour of the Duck Creek Formation, Frederickson's wife (and then-girlfriend) Janessa Doucette-Frederickson slipped over a boulder. She noticed a massive vertebra protruding from the ground. The team eventually managed to dig out three vertebrae — each of which measured 4.5 inches in diameter!

"We thought it was a really large fossil and we all came together and dug it out," said Frederickson. "We realized it was a really large shark."

Later examination revealed that what they had stumbled upon was in fact a massive fossil — that of an ancient shark. The dimensions of the vertebrae led the researchers to determine that the gigantic shark in question would have been between 20 and 22 feet long.

The researchers studied ecosystems belonging to the Mesozoic Era and concluded that shark remains previously unearthed in Kansas and the newly discovered Texan specimen were Leptostyrax macrorhiza.

The discovery was announced by researchers from the University of Oklahoma in the journal Plos One on Wednesday, June 3.

"These specimens are important because they represent some of the largest published lamniform shark vertebrae from the Early Cretaceous of North America," reads the article entitled "A Gigantic Shark from the Lower Cretaceous Duck Creek Formation of Texas."

The ancient sharks belong to the lamniform family, which includes the Great White. However, the fossilized remains of the "gigantic shark" seems to be double the size of the well-known modern predator.

This study was published in the journal PLOS ONE.

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