A rare fossil swan discovered in the remains of an ancient lake in Central Otago has changed scientists’ understanding of the evolution of New Zealand’s unique bird life. The discovery adds to growing evidence that the origins of Aotearoa’s birds were far more dynamic than previously thought, according to researchers at the University of Otago – Otakau Whakaihu Waka.
Director of the Otago Palaeogenetics Laboratory, Associate Professor Nick Rawlins, is co-author of the new study, which examines the fossil and its evolutionary relationships.
Research, published in historical biologyThe study was carried out by an international team from the University of Otago, New Zealand Museum Te Papa Tongarewa and the University of Cambridge (UK). Scientists examined fossil material obtained from the famous St. Bathans fossil deposits.
A new species hidden among the fossils
Rawlins reported that although waterfowl fossils are abundant in St. Bathans, swan remains are much less common.
To investigate further, the team re-examined every fossil bone previously thought to belong to a swan. They compared those remains to those of other fossil waterbirds from the site, as well as an extensive collection of modern and extinct bird skeletons.
“We determined that the bones included an undescribed species, about the size of a small swan,” he says.
Newly identified bird has been named meterchain looted. Its name is inspired by the nursery rhyme Old Mother Goose, which reflects the idea of an ancient swan emerging from the soil of a fossil deposit. meterchain Whereas, in ancient Greek it means “mother swan”. plundered Latin for “of mud.”
Rawlins stated that “the St. Bathans swan is not closely related to the recently extinct giant flightless New Zealand swan (Cnemiornis species) or their Australian cousins, the Cape Barren swan.”
New Zealand bird evolution reconsidered
Combined with recent genetic evidence, the discovery shows that New Zealand’s bird history is far more complex than scientists had realized.
Te Papa lead author Alan Tennyson said many bird species have arrived in New Zealand over millions of years, but the ancestors of some of the country’s most famous large birds arrived surprisingly recently. Recent arrivals, dating back only four to five million years, include the takahe, Forbes’s harrier, and the giant Haast’s eagle.
“An earlier theory argued that the St Bathans swans represented the direct ancestors of the giant flightless Cnemiornis Geez, which means this lineage had a very long history (at least 14 million years) in Zealandia,” he says.
“However, this conflicts with genetic evidence suggesting the ancestors Cnemiornis It came from Australia only seven million years ago, which was rejected by proponents of the earlier theory.
“Our rigorous reassessment supports the later arrival theory.”
DNA and fossils reveal a more dynamic past
According to Rawlins, the ancestors of the St. Bathans swan arrived in Zealandia more than 14 million years ago, but their lineage eventually disappeared without leaving living descendants.
“Using all the tools in the toolbox, including DNA and fossils, we can reconstruct how Zealandia’s dynamic geological, climatic and human history has shaped the evolution of the Aotearoa fauna,” he says.
That giant flightless Cnemiornis Geese provide another remarkable example of how quickly island species can change.
“The relatively recent evolution of giant flightless Cnemiornis Geese represent another remarkable example of the rapid morphological change that can occur within short time frames on islands. At over a meter long and weighing up to 18 kilograms, they were the largest swans in the world.”