Taranaki fossil hunters have found specimens of an extinct monk seal, believed to be three million years old.
The fossil hunters discovered partial skulls of the animal, named Eomonachus belegaerensis, on south Taranaki beaches from 2009-2016.
The seal is named after the fictional Belegaer sea from J.R.R. Tolkien's Lord of the Rings. Eomonachus belegaerensis is believed to have lived in New Zealand waters around three million years ago, were 2.5 metres long and weighed around 200-250kg.
The find has changed the understanding scientists have of seal evolution. Seals are the most widely dispersed semi-aquatic marine mammals, thought to have evolved in the north Atlantic. Eomonachus belegaerensis provides evidence to show seals evolved in the Southern Hemisphere and then went north.
The specimens were found by Stratford High School science teacher John Buchanan-Brown, Karl Raubenheimer, David Allen and Alistair Johnson.
John says he has been collecting fossils for over 50 years.
"When I lived in Sussex I walked along the beach with my dad and we would pick up sea urchin fossils. He had found a really nice one and I remember thinking 'that's it, I've got to find something better'. He passed away a few years ago and it is a shame he can't see what I've found. He understood why I like fossil hunting better than anyone."
John found the partial skull of the Eomonachus belegaerensis in 2010.
"I was walking the beach with Karl and he went one way and I went the other. I was so happy to have found it. When I flipped the piece of rock over, I could see the outline. I knew I got a skull as I could see the roof of the mouth and cranium. I knew it was a seal because of its structure and shape but at that point I didn't know how special the find was. I've been collecting from that site for nearly 15 years now."
He says the fossils can be difficult to find.
"You're looking for a thin brown line amongst grey rock and there is a lot of rock."
Once he found the fossil, it took him a week to clean and prep the skull with specialised equipment.
John says he and the other fossil hunters often contact Te Papa Tongarewa and Canterbury museum when they find something.
"We like to keep them in the loop with what we find in case it is something of scientific importance and in this case, it was."
John says he encourages everyone to try fossil hunting.
"It is great fun but if you do find something, I advise people to contact local museums instead of trying to get the fossil out of the rock itself to avoid damaging the fossil."
A paper based on their findings has been written and published by the Royal Society this year.
The paper is a collaboration between Te Papa Tongarewa, Canterbury Museum, University of Otago's department of geology, Monash University in Victoria, Australia, Australian museums and the Smithsonian Institution in Washington, DC. The four fossil hunters have been credited in the paper.
"The paper has been four years in the making and involves a great deal of work. The picture it paints for seal evolution is wonderful."