Ancient Fossil Cache in New Zealand Reveals Prehistoric Ecosystem and Kākāpō Ancestry

A significant paleontological discovery in a cave near Waitomo on New Zealand’s North Island is providing scientists with an unprecedented glimpse into a lost ecosystem. An international team of researchers from Australia and New Zealand has uncovered the remains of frogs and birds dating back approximately one million years, including a previously unknown relative of the iconic kākāpō.

This find represents the first time a substantial collection of terrestrial vertebrate fossils from this specific era has been recovered in New Zealand. The assemblage includes fossils from 12 bird species and four frog species, offering a rare window into the islands’ biodiversity long before human arrival.

Published in Alcheringa: An Australasian Journal of Palaeontology, the study suggests that New Zealand’s wildlife was undergoing profound transformations well before human settlement. Catastrophic volcanic activity and rapid climate fluctuations repeatedly altered habitats, triggering extinctions and creating evolutionary opportunities for new species.

Ancient Avifauna Lost to Time

Associate Professor Trevor Worthy of Flinders University notes that these fossils reveal a bird community entirely distinct from the current avian population of New Zealand.

“This is a newly recognized avifauna for New Zealand, one that was replaced by the one humans encountered a million years later,” says Associate Professor Worthy, from the College of Science and Engineering at Flinders University. “This remarkable find suggests our ancient forests were once home to a diverse group of birds that did not survive the next million years.”

The study was a collaborative effort involving paleontologists from Flinders University and the Canterbury Museum, alongside volcanologists Joel Baker of the University of Auckland and Simon Barker of Victoria University of Wellington. The team estimates that between 33% and 50% of species vanished during the million-year interval preceding human arrival in Aotearoa New Zealand.

Environmental Upheaval and Habitat Shift

Researchers attribute these prehistoric losses to natural environmental volatility. “These extinctions were driven by relatively rapid climate shifts and cataclysmic volcanic eruptions,” explains co-author Dr. Paul Scofield, Senior Curator of Natural History at the Canterbury Museum.

The discovery fills a massive void in the regional fossil record. “From our excavations at St Bathans in Central Otago over many years, we have a snapshot of life in Aotearoa between 20 and 16 million years ago. These new findings cast light on the 15 million year period from then to 1 million years ago, which is largely absent from New Zealand’s fossil record,” says Dr. Scofield. “This wasn’t a missing chapter in New Zealand’s ancient history; it was a missing volume.”

A Flying Ancestor of the Kākāpō

Among the most significant finds is Strigops insulaborealis, an ancient relative of the kākāpō. While the modern kākāpō is the world’s only flightless parrot—characterized by its heavy build and nocturnal habits—its ancestor may have been quite different.

Analysis of the fossilized skeletal structure indicates that S. insulaborealis had weaker legs than the modern kākāpō. Since contemporary kākāpō rely on powerful legs for climbing and movement, researchers hypothesize that this ancient relative spent less time climbing and may have retained the ability to fly. Further research is required to confirm its flight capabilities.

The site also yielded fossils of an extinct ancestor of the takahē and an extinct pigeon species closely related to Australia’s bronzewing pigeons. Dr. Scofield suggests that the shifting forest and shrubland habitats forced a “reset” of bird populations, acting as a primary driver for the evolutionary diversification of fauna on the North Island.

Precise Dating via Volcanic Ash

The scientific value of the discovery is enhanced by the precision with which the fossils can be dated. The remains were found sandwiched between two layers of volcanic ash: one from an eruption roughly 1.55 million years ago and another from a massive event approximately one million years ago.

This geological positioning provides clear chronological boundaries. The younger eruption likely blanketed the North Island in meters of ash; while most of this material was lost to erosion and rain, some remained preserved within the cave. Additionally, the older ash layer confirms that this site is the oldest known cave on the North Island.

Redefining Natural History

Associate Professor Worthy emphasizes that these fossils provide a critical baseline for understanding the evolution of New Zealand’s wildlife.

Historically, scientific focus has been centered on the ecological shifts following human arrival roughly 750 years ago. However, this evidence proves that powerful natural forces were sculpting the islands’ unique biological identity long before then.

“For decades, the extinction of New Zealand’s birds was viewed primarily through the lens of human arrival 750 years ago,” Worthy explains. “This study proves that natural forces like super-volcanoes and dramatic climate shifts were already sculpting the unique identity of our wildlife over a million years ago.”

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