Telford student Tom McFarlane was combing an unnamed Catlins beach in July, when he turned over an innocuous looking boulder.
He could hardly believe his eyes when he saw what was embedded in the heavy rock, the Dunedin-born 18-year-old, who had been an avid fossil hunter since he was about 7, said.
"I’m used to finding fossilised crabs and shells and stuff, so I had to look pretty closely when I saw it at first.
Tom said he had been thinking about what steps to take since the discovery, and decided to post photos to a Facebook forum yesterday morning.
He said forum members suggested it might be an ichthyosaur fossil.
"It could be a smallish ichthyosaur. The ribcage is about the size of a large dog. It would be cool to get it properly looked at."
University of Otago geology department Emeritus Prof Daphne Lee said a quick examination of the available photos suggested it could be an ichthyosaur.
"I’m not an expert, but I have consulted with colleagues who tell me the age and appearance of the fossil and rock bear a strong resemblance to the five other ichthyosaur fossils in the department’s collection, three of which are from Southland.
"If that were the case, this would be mid to late Triassic in age — about 240 [million to] 200 million years ago — and certainly a very interesting find that we would like to explore further."
Ichthyosaurs were the marine-dwelling apex predators of their time, some species of which were believed to grow up to 30m in length.
She said any further investigation of the fossil, which Tom had left in place on the beach, would need to be undertaken sensitively, in consultation with interested parties.
"We would need to examine it properly, and possibly retrieve it for conservation if it’s in a vulnerable position on the beach, for example. Only then could we confirm it’s an ichthyosaur."
