Is the world's oldest shark really 512 years old?

Last week, several publications around the world reported the discovery of a 512-year-old Greenland shark – apparently making it older than William Shakespeare, who was born in 1564.

The oldest shark in the world was discovered living in the North Atlantic Ocean, these reports said, noting that it could live on to be 600.

A shark that old would have lived through major world events such as the founding of the US, the Industrial Revolution and both the World Wars, the reports surmised.

But, did researchers actually put the age of the world's oldest shark at exactly 512?

IBTimes UK reached out to Danish marine biologist Julius Nielsen who has, along with other researchers, used radio carbon dating to study the life span of Greenland sharks.

"The finding of a Greenland shark being estimated somewhere between 272-512 years old was published in Science in 2016," Nielsen said, referring to his research work published in August 2016.

Nielsen and his team had studied 28 Greenland sharks and revealed the age of the largest one to be 392 years plus or minus 120 years, which means the shark could be as old as 512, but that was only an estimation.

Soon after reports of the discovery of the oldest living shark began making the rounds, Nielsen, took to Instagram to put speculation to rest: "Social media are going beserk over old Greenland sharks these days. All of this is just the same story coming to life from August 2016 and please note that we have not found any sharks to be 600 or 500 yr old.... we have ESTIMATED (meaning that it has not been verified)."

Earlier, Professor Kim Praebel from the Arctic University of Norway had found that Greenland sharks could have a lifespan of up to 400 years. Scientists generally use bony structures such as calcified vertebrae to track age of many shark species, but Greenland sharks – found in the Arctic Sea – are "soft sharks", whose vertebrae don't harden enough to form tell-tale age markers.

So, researches used radiocarbon dating of eye lens nuclei from these sharks, which indicated an average lifespan of 272 years, with some living to 400 years. Furthermore, they found the sharks only reach sexual maturity at 150 years.