A fish fossil pulled from a near-unreachable cliff on Pitt Island in 1999 has finally been fully documented, after the late collector’s field notebooks turned up nearly 30 years later.

The fossil, found by Dr Richard Köhler during a research expedition to Pitt Island in the Chatham Islands, was embedded in a steep section of cliff on the island’s western coastline above Waihere Bay.

According to the University of Otago, Köhler spotted the three-dimensionally preserved, mummified fish fossil, then walked 3 kilometres back to his lodging in Flowerpot Bay to borrow a ladder. He returned to the site and extracted the fossil in several large, extremely heavy blocks.

Back in Dunedin, Köhler took the specimen to the University of Otago’s Department of Geology, where Emeritus Professor Daphne Lee said she and the late Professor Ewan Fordyce immediately saw its importance.

“It was quite unlike any other fish fossil known from Aotearoa, New Zealand,” Daphne says.

The fossil was later prepared by the late fossil preparator Andrew Grebneff and remained in the department’s collection for several years. It eventually drew the attention of Professor Mike Gottfried, a fossil fish specialist from Michigan State University, who had previously worked with Ewan on fossil fish and shark studies from New Zealand.

Researchers found the 1.2 metre fossil was a tarpon, a species no longer found in New Zealand waters. Modern tarpon are large predatory fish that typically swallow smaller fish whole, and the fossil’s anatomy suggested it lived in much the same way.

The University of Otago said its elongated body, thick rigid scales, powerful tail fin and large upward-facing mouth pointed to an active predator near the top of the food chain.

But the work stalled because key geological details about the exact discovery site were missing, and Köhler had died several years earlier.

By the time Ewan Fordyce died in November 2023, a draft scientific paper had already been prepared. Researchers still could not complete the study because they did not have the detailed field information needed to document where and how the fossil had been found.

That changed in early 2025, when one of Köhler’s children, who was studying at Otago, visited the department looking for photographs of his father. After meeting Daphne Lee, the family donated Köhler’s field notebooks, including those from the original Pitt Island expedition.

“This enabled us to get enough specific locality information to prepare a Fossil Record Form and to scientifically catalogue the fossil,” Daphne says.

The completed study has now been published in the New Zealand Journal of Geology and Geophysics. The researchers said it is the first report of a high-in-the-food-chain pursuit predatory bony fish from Paleogene-aged rocks, around 55 million years old, in Aotearoa.

The fossil was named Ikawaihere koehleri, after Richard Köhler and the place where it was found. The authors also thanked Heidi Lanauze and the Hokotehi Moriori Trust for approving the name.

Mike Gottfried said it was a privilege to work on the “remarkable fossil.”

“It greatly expands our knowledge of the evolutionary history of tarpons, and it preserves unique and unusual features in exquisite 3D detail,” he says.

“It is certainly among the most important and impressive fossils recovered to date from Aotearoa, New Zealand.”

Daphne Lee said she was pleased the study had finally been completed.

“It is a fitting tribute to Richard, Ewan and Andrew. We’re extremely grateful to Richard’s family for donating his notebooks, we could not have done this without them.”

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