Study of predatory fossil fish honours late researchers

Recently-revealed notebooks belonging to a late paleontologist contain the missing information needed to help researchers finish their study of a “remarkable” fossil discovered nearly three decades ago.

In 1999, Dr Richard Köhler found the fossil fish during a research trip to Pitt Island, in the Chatham Islands.

Richard saw the three-dimensionally preserved, mummified fossil in an almost unreachable section of cliff above Waihere Bay, on the western coast of the island.

He walked 3km back to his accommodation in Flowerpot Bay to borrow a ladder and returned to the area to carefully retrieve the fossil in several large and very heavy blocks.

Back in Dunedin, he took the fossil to the University of Otago’s Department of Geology where Emeritus Professor Daphne Lee says she and the late Professor Ewan Fordyce were “suitably impressed” by the find.

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

The fossil was meticulously prepared by late preparator Andrew Grebneff and stored in the Department until it caught the eye of fossil fish expert Professor Mike Gottfried, from Michigan State University, several years later.

Having co-authored several papers on fossil fishes and sharks from New Zealand with Ewan, Mike began studying the fish.

The 1.2m long mummified fossil turned out to be a tarpon, a fish no longer found in New Zealand seas.

Living tarpon are large and powerful predators that swallow their prey, typically smaller fish, whole.

The long, powerful body of the fossil, with thick rigid scales, a strongly developed tail fin, and large gaping, upward-facing mouth, suggests it had a similar lifestyle.

However, some key geological information about where the fossil was found was lacking, since Richard had sadly passed away some years earlier.

By the time of Ewan’s death in November 2023, a draft research paper was underway, but progress had halted due to the lack of detailed information about how the fossil was discovered.

That was until one of Richard’s children, a student at Otago, visited the Department in early 2025 in the hope of finding photos of his father.

After meeting Daphne, Richard’s family ended up donating his field notebooks, including those from his Pitt Island trip.

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

The paper was recently published in the New Zealand Journal of Geology and Geophysics. It is the first report of such a high-in-the-food-chain pursuit predatory bony fish in rocks of Paleogene age (around 55 million years ago) from Aotearoa.

The fossil was named Ikawaihere koehleri to acknowledge Richard and the location where the fossil was discovered. The study’s authors are grateful to Heidi Lanauze and the Hokotehi Moriori Trust for approving the name.

Mike says 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 says she’s very pleased that the paper is finally finished.

“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.”