Recently recovered field notes from a deceased paleontologist have provided critical missing information that researchers needed to complete the study of a remarkable fish fossil discovered nearly 30 years ago.
The story began in 1999 when Dr. Richard Koehler discovered the fossil during a research expedition to Pitt Island in the Chatham Islands.
While exploring the island’s western coastline above Waihele Bay, Koehler discovered three-dimensionally preserved mummified fish fossils embedded in a steep section of an almost inaccessible cliff.
To get it back, he walked 3km back to his accommodation in Flowerpot Bay to rent a ladder. He then returned to the site and carefully extracted the fossil in several large, very heavy blocks.
When Mr Köhler returned to Dunedin, he took the specimen to the University of Otago’s Department of Geology. Emeritus Professor Daphne Lee recalls that she and the late Professor Ewan Fordyce quickly recognized its importance.
“It was completely unlike any other fish fossil known from Aotearoa New Zealand,” Daphne said.
Remarkable ancient predator identified
The fossil was painstakingly created by the late fossil creator Andrew Grebnev and remained in the ministry’s collection for several years. Eventually, this caught the attention of Professor Mike Gottfried, a fossil fish expert at Michigan State University.
Mike had previously collaborated with Ewan on several studies of New Zealand fish and shark fossils, and immediately began investigating this rare specimen.
Researchers determined the mummified fish, measuring 1.2 meters long, was a tarpon, a species no longer found in New Zealand waters.
Modern tarpon are large predatory fish that usually swallow small fish whole. The anatomy of this fossil suggests that it lived much the same way. Its elongated body, thick, hard scales, powerful caudal fins, and large, upturned mouth all indicate that it is an active predator near the top of the food chain.
Lack of information delays research
Despite the fossil’s importance, researchers faced major obstacles.
Important geological information about the exact location of the discovery is missing, and Richard had passed away several years ago.
By the time of Ewan’s death in November 2023, a draft of the scientific paper was already in place. However, the work could not move forward because researchers lacked the detailed local information needed to properly document where and how the fossils were found.
The breakthrough occurred in early 2025 when one of Richard’s children, who was studying at the University of Otago, visited the department looking for a photo of his father.
After meeting with Daphne, Richard’s family decided to donate his field notes, including those from the first Pitt Island expedition.
“This gave us enough specific locality information to create a fossil record form and scientifically catalog the fossils,” Daphne says.
Naming of new fossil species
The completed research was recently New Zealand Journal of Geology and Geophysics.
Researchers say this is the first report tracking a predatory teleost fish high up the food chain in Aotearoa’s Paleogene (about 55 million years ago) rocks.
the fossil was named Ikawaihere Kereri In honor of Richard Koehler and the place where it was discovered. The authors also thanked Heidi Ranauze and the Hokotehi Moriori Trust for approving the name.
Mike says it was a privilege to work on the “amazing fossils”.
“This greatly expands our knowledge of the evolutionary history of tarpon, preserving unique and rare features in exquisite 3D detail,” he says.
“This is certainly one of the most important and impressive fossils ever recovered in Aotearoa New Zealand.”
Daphne says she’s glad the research is finally complete.
“This is a fitting tribute to Richard, Ewan and Andrew. We are extremely grateful to Richard’s family for donating the notebook; without them this would not have been possible.”
