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A cave discovery on New Zealand’s North Island has revealed fossils from an ancient ecosystem that existed more than one million years ago. The remains show that large-scale species turnover was already underway long before humans arrived.
The fossil collection includes birds and frogs preserved between volcanic deposits, capturing a period of New Zealand’s history that had remained largely undocumented. For many years, extinction in New Zealand was most often discussed in connection with human settlement around 750 years ago. The newly described fossils point to much older environmental changes that influenced which species survived and which disappeared.
According to the study published in Alcheringa: An Australasian Journal of Palaeontology, the remains belong to a previously unknown community of animals that occupied North Island forests during the early Pleistocene. Scientists describe the site as the first direct evidence from a long-missing interval in the region’s fossil record.
Volcanic Ash Preserved an Ancient Forest
The fossils were recovered from a cave where sediment had been sealed between two volcanic ash layers formed during separate eruptions. Researchers dated the lower ash deposit to around 1.55 million years ago and the upper layer to approximately 1 million years ago.
Inside that natural archive, the team identified fossils representing 12 bird species and four frog species. Several of the birds had not previously been recognized by science.
According to Trevor Worthy of Flinders University, who led the study, the discovery documents a bird community that no longer existed by the time people reached New Zealand.
“This is a newly recognized avifauna for New Zealand, one that was replaced by the one humans encountered a million years later,” Worthy explianed in a statement published by the Canterbury Museum. “This remarkable find suggests our ancient forests were once home to a diverse group of birds that did not survive the next million years.”
Researchers noted that the ancient forests represented by the fossils supported a mix of species unlike those associated with present-day ecosystems. The collection also fills a major chronological gap in scientific knowledge of New Zealand’s natural history.
Earth Changed Before Humans Arrived
The study suggests that extinctions were already changing biodiversity across North Island long before humans arrived. Using the fossil evidence, researchers estimate that around 33 to 50 percent of species on the island disappeared during the million years before people settled there.
As explained by Paul Scofield, who co-authored the study and is Canterbury Museum’s Senior Curator of Natural History, changing climate conditions and major volcanic events were likely behind much of that decline. Worthy said the results challenge a long-held view of how extinctions unfolded in New Zealand.
“For decades, the extinction of New Zealand’s birds was viewed primarily through the lens of human arrival 750 years ago. 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.”
New Fossil Finds Reveal an Unfinished Story
Among the fossils, scientists highlighted the identification of Strigops insulaborealis, a newly described parrot species related to the modern Kākāpō. The team suggested this ancient relative may have retained flight capability.
Their interpretation came from anatomical observations showing weaker legs than those of the living Kākāpō, which is known for its flightless lifestyle and climbing ability. They also noted that additional work is needed before confirming that possibility.
The cave also yielded fossils linked to an ancestor of the modern Takahe and remains from an extinct pigeon closely related to Australian bronzewing pigeons.
Scofield said environmental changes repeatedly reshaped ecosystems and allowed new forms of wildlife to emerge.
“The shifting forest and shrubland habitats forced a reset of the bird populations,” he said. “We believe this was a major driver for the evolutionary diversification of birds and other fauna in the North Island.”
Researchers also noted that earlier excavations had already uncovered evidence of life in New Zealand dating from 20 to 16 million years ago. This discovery provides the first evidence from the period between 15 million and 1 million years ago, filling in a long-missing part of the country’s ancient history.