A "lost world" about a million years old has been found in a New Zealand cave

Australian and New Zealand scientists have discovered a collection of terrestrial vertebrates about 1 million years old in a cave near Waitomo on New Zealand's North Island (Aotearoa), the country's rarest collection of terrestrial vertebrates.

This is the first time such a "massive" set of Early Pleistocene fossils has been found in New Zealand - and it gives a glimpse of what local ecosystems looked like long before humans arrived.

According to the researchers, the cave sediments contain the remains of at least 12 species of ancient birds and four species of frogs. The team calls the finding a kind of "window" into the past: for New Zealand it is the period between older locations (for example, the famous layers of St. Bataans age 20-16 million years) and relatively "young" late Quaternary remains are usually almost not represented in the fossil record.

The key conclusion of the paper is that notable rearrangements of the fauna occurred here without human involvement. The authors suggest that in the million years before human settlement of the islands, about one-third to one-half of the species disappeared. The main "engines" of extinctions and species replacement could be sharp climatic fluctuations and large volcanic events that can quickly change forest and shrub landscapes and literally restart ecosystems.

One of the most intriguing findings was a new parrot species, Strigops insulaborealis, an ancient relative of the modern kakapo. Today, the kakapo is known as a heavy, nocturnal and flightless bird, but its million-year-old ancestor, according to preliminary signs, could be more "mobile": it, judging by the bones, had weaker legs, which hints at a different style of movement and less "specialisation" to climbing. The researchers emphasise that the question of the ancient species' ability to fly requires further data.

In addition, they found an ancestor of the modern takahe in the cave, which helps trace the evolution of one of New Zealand's most recognisable birds, as well as an extinct species of pigeon related to Australian bronze-winged pigeons. Taken together, these findings indicate that the North Island was undergoing major waves of faunal 'renewal' long before human influence.

Geology provided the precise dating: the bone-bearing layers were sandwiched between two horizons of volcanic ash. The lower layer is attributed to an eruption about 1.55 million years ago, the upper layer to a catastrophic event about 1 million years ago that could have covered much of the North Island with metre-thick ash. This "ash corridor of time" makes the find particularly valuable: it provides a missing baseline for reconstructing New Zealand's natural history and revisiting how the island's unique fauna was formed.