In the mudstones of St Bathans, Central Otago, scientists have uncovered a fossil goose that adds a surprising twist to the evolutionary story of New Zealand’s birds. The deposits, dating to the early–middle Miocene (around 16–19 million years ago), are already famous for their rich avian fossils, especially ducks and geese. But a reassessment of 11 bones once thought to belong to geese has revealed something unexpected: a previously unknown species.
Associate Professor Nic Rawlence of the University of Otago explains: “We determined that the bones included an undescribed species, the size of a small goose.”
The team named it Meterchen luti, drawing on the nursery rhyme Old Mother Goose. Meterchen means “mother goose” in ancient Greek, while luti is Latin for “of the mud”, a nod to the fossil’s resurrection from the ancient lakebed.
The study, published in Historical Biology, shows that four of the bones belong to the tadornine duck Miotadorna sanctibathansi, five probably to a large anatid such as the purported goose Notochen bannockburnensis, and one or two to the new goose species Meterchen luti.
A reconstruction of the St Bathans goose (Metechen luti). Artwork by Sasha Votyakova, © Te Papa CC BY 4.0
None of the fossils showed a clear connection to cereopsine geese, contradicting earlier claims that this lineage had a long history in Zealandia during the Miocene. Instead, the findings match genetic evidence indicating that the ancestors of the giant, flightless Cnemiornis geese arrived much later, specifically in the late Miocene.
Lead author Alan Tennyson of Te Papa highlights the significance: “An earlier theory argued that the St Bathans goose represented the direct ancestors of giant flightless Cnemiornis geese, implying this lineage had a very long history (of at least 14 million years) in Zealandia.”
“However, this conflicts with genetic evidence suggesting the ancestors of Cnemiornis arrived from Australia only about seven million years ago. Our rigorous reassessment supports the later arrival theory.”
This reinterpretation shows how lively New Zealand’s bird history has been. Many well-known species, like the takahē, Forbes’ harrier, and the giant Haast’s eagle, appeared surprisingly recently, within the last four to five million years.
Rawlence notes: “Using all the tools in the toolbox, including DNA and fossils, we can reconstruct how the dynamic geological, climatic and human history of Zealandia has shaped the evolution of Aotearoa fauna in ever more detail.”
The story of Metarchen luti is one of arrival and extinction: its lineage reached Zealandia more than 14 million years ago, but left no descendants. Meanwhile, the later-arriving Cnemiornis evolved rapidly into one-meter-tall, 18-kilogram giants, the largest geese in the world.
Collectively, these findings reveal that the story of New Zealand’s birds is not just an immutable tale of ancient lineages barely changed. Rather, it is a fluid narrative of emergences, extinctions, and pivotal macroevolutionary transitions. The mud of St Bathans should still teach us that incomplete fossils can be important in changing our view of the evolution of life in Zealandia.
Journal Reference:
- Alan J. D. Tennyson, Elizabeth M. Steell, Pascale Lubbe, Amy L. Adams, Liam Greer, Alex H. Brown, Laura J. E. Wilson, Timothy C. Campbell, Tobia C. Dale, Nicolas J. Rawlence. A review of fossil goose (Aves: Anserinae) records from the Miocene St Bathans deposits, New Zealand, with the description of a new species. Historical Biology. DOI: 10.1080/08912963.2025.2601236