Researchers have found an ancient shark in the North Atlantic, believed to be 512 years old, which could be the oldest living vertebrate in the world. While the animal was discovered months ago, its potential age was revealed in a study in the journal Science.

Marine biologist Julius Nielsen found an 18-foot Greenland shark his team had been studying was at least 272 years old and possibly as old as 512 years. While the exact time of the discovery remains unknown, the news resurfaced as Neilsen completed his PhD thesis on Greenland sharks.

Earlier this year professor Kim Praebel, from the Arctic University of Norway, found that Greenland sharks could have a lifespan of up to 400 years. But the recent research proves that the species could live to be even older. With the help of a mathematical model analyzing the lens and the cornea that linked size with age, researchers found a way to predict age. The method to discover the age of the animal was determined last year.

By measuring the size of the recent Greenland shark found, researchers suggest the animal could have been born as early as 1505, making it even older than Shakespeare. Greenland sharks — also known as the gurry sharks, or grey sharks, are large sharks of the family Somniosidae — grow at a rate of one centimeter a year, enabling scientists to determine their age by measuring their size.

The shark that was found to be 512 years old was one of 28 Greenland sharks to be analyzed by the scientists.

"It definitely tells us that this creature is extraordinary and it should be considered among the absolute oldest animals in the world," Nielsen said last year.

Steven Campana, a shark expert from the University of Iceland, said last year: "Fish biologists have tried to determine the age and longevity of Greenland sharks for decades, but without success. Given that this shark is the apex predator (king of the food chain) in Arctic waters, it is almost unbelievable that we didn’t know whether the shark lives for 20 years, or for 1,000 years."

Greenland sharks are found in deep water in the Atlantic Ocean, from Canada to Norway. The species is often plagued by worm-like parasites that latch on to their eyes. These sharks have been known to feast on rotting polar bear carcass.

In September, Nielsen shared a stomach-churning photo of the remains of a polar bear extracted from the stomach of a Greenland shark.

"And no, I don’t think the shark attacked the bear," Nielsen wrote. "It is much more likely a carcass found by the shark. Polar bear remnants in Greenland shark stomachs are extremely rare and polar bears are considered of no importance as food source for sharks in Greenland waters."

Praebel had been looking into how Greenland sharks' "long life" genes could shed light on what determines life expectancy in different species, including humans.

"This is the longest living vertebrate on the planet," he said. "Together with colleagues in Denmark, Greenland, USA, and China, we are currently sequencing its whole nuclear genome which will help us discover why the Greenland shark not only lives longer than other shark species but other vertebrates."

Amid the study into "long-life" genes, studies have also shed new light on the shark's behavior.

"Since the Greenland shark lives for hundreds of years, they also have enough time to migrate over long distances and our genetic results showed exactly that," Praebel reportedly said. "Most of the individuals in our study were genetically similar to individuals caught thousands of kilometers away.

"We still do not know where and how the Greenland shark reproduce, but the results we presented here in Exeter showed that the shark may prefer to mate in deep hidden fjords of the Arctic," Praebel said.