Milia, Greece  - When Athanasios Delivos first found fossils where his cattle were grazing near the tiny village of Milia in northern Greece years ago, he never imagined they would lead to the startling discovery of two massive prehistoric tusks - the largest ever found.

"My wife kept on nagging me to throw away the fossils I was finding but I knew that something big - huge - which was not human nor animal was just waiting to be found," the 83-year-old Delivos said at the recent ceremony to acknowledge the find as a Guinness World Record.

His persistence drew a team of experts from the University of Thessaloniki to Milia, about 250 miles north of Athens, where the 4,39-metre tusk of a mastodon - a primitive elephant-like animal - was unearthed in 1997.

Almost 10 years later, the petrified remains of a second mastodon, or mammut borsoni, were found in a sandpit nearby. The tusk, along with the jaw and leg bones of the prehistoric mammal, made it the largest ever uncovered.

"To find a tusk 5 metres long, that is a fantastic surprise," said Evangelia Tsoukala, a palaeontologist at the University of Thessaloniki and who led the team of Greek and international experts that excavated the site in 2007.

Tsoukala, whose excavations have uncovered several prehistoric animals in the area over the past decade, said the two massive tusks belonged to a male animal that lived in Milia about 3 million years ago and was in its prime - about 25-30 years - at the time of death.

Like the woolly mammoth, mastodons had straighter tusks, and stockier skeletons while their teeth and metabolism were optimised for a diet of softer food such as leaves, fruit and small twigs.

Researchers say the tusks were probably used to break branches and twigs although some evidence suggests males may have used them in mating challenges.

"The massive tusks belonged to a mammal that was about 3.5 metres tall at the shoulder and weighed about 6 tons," she said, adding that it probably needed to consume 300 kilograms of food and 200 litres of water a day.

Mastodons, an ancestor of the elephant, roamed North America, Africa and Asia, but how they became extinct remains largely a mystery.

One theory is that climate change was responsible for the animal's disappearance while recent studies indicate that tuberculosis may have been responsible for the extinction of the mastodon 10,000 years ago.

Dutch researcher Dick Mol, who participated in the Greek excavation, said the find at Milia provides evidence of a lost world and clues about the mastodon's ultimate fate.

"The environment that the mastodon was living in back then is completely different from today's - it was more tropical with high humidity and with the existence of big rivers."

He said that until now no DNA material has been recovered in the bone remains but that the findings were being shared among genetic experts in an effort to provide clearer insight into the animal's evolutionary development.

"The aim is not to bring these mammals back to life, because even if we were able to clone them they would still not be able to survive in today's climate conditions," said Mol.

Conducting the dig in just two weeks, Tsoukala said one of the hardest aspects of the project was moving the great tusks without harming them to rest in their permanent home at the village's tiny Museum of Natural History.

It took a team of more than 15 people to carefully remove them from the ground. There are plans to build a life-sized replica of the animal in the future, once funding is made available.

For a country such as Greece that focuses its efforts on recovering lost archaeological treasures, the discovery is seen as one of the most important in the field of palaeontology.

"We focus so much attention on archaeology that we forget about the importance of prehistoric Greece," said Tsoukala.

Today, standing proudly in front of the tusk display, Delivos says he gladly gave up his work as a farmer so that he could give tours at the museum.

"I feel like I came across a gold mine - I am the envy of the entire village." (dpa