A rare fossil goose, unearthed from the depths of an ancient lake in Central Otago, is rewriting the narrative of New Zealand's avian history. This discovery, led by Associate Professor Nic Rawlence from the University of Otago, challenges the conventional understanding of the country's unique bird life evolution. The fossil, named Meterchen luti, is a small, undescribed species of goose, distinct from the recently extinct giant flightless New Zealand geese and their Australian counterparts. This finding, published in Historical Biology, is part of an international collaboration involving the University of Otago, the Museum of New Zealand Te Papa Tongarewa, and the University of Cambridge.
The St Bathans fossil deposits, renowned for their waterfowl fossils, have now revealed a new species that adds complexity to the evolutionary story of New Zealand's birds. The research team, including Rawlence, re-examined fossil bones previously identified as geese, comparing them with other fossil waterfowl and modern bird skeletons. This meticulous process led to the discovery of Meterchen luti, a small goose-sized bird, whose name pays homage to the nursery rhyme Old Mother Goose and the ancient Greek term for 'mother goose'.
This find challenges the earlier theory that the St Bathans goose was the direct ancestor of the giant flightless Cnemiornis geese, a lineage believed to have a 14-million-year history in Zealandia. Instead, genetic evidence suggests that the ancestors of Cnemiornis arrived from Australia only about seven million years ago. This reassessment supports the idea that the ancestors of the St Bathans goose reached Zealandia over 14 million years ago but eventually disappeared without leaving surviving descendants.
The study highlights the dynamic nature of New Zealand's bird evolution, with many species arriving over millions of years. However, some of the country's best-known large birds, such as takahē, Forbes' harrier, and the giant Haast's eagle, have more recent origins, dating back only four to five million years. This discovery underscores the importance of combining DNA and fossil evidence to reconstruct the intricate relationship between geological, climatic, and human history in Zealandia and its impact on the evolution of Aotearoa's fauna.
In my opinion, this discovery is a fascinating reminder of the ongoing nature of scientific inquiry and the importance of re-evaluating established theories. It also highlights the dynamic and complex nature of New Zealand's natural history, with new species and evolutionary relationships continually being uncovered. As we continue to explore and study our planet's past, we may uncover even more surprising and insightful discoveries that challenge our understanding of the natural world.
