Australia’s largest eagle discovered at last

An eagle twice the size of the modern-day apex predator the wedge-tailed eagle, which soared over southern Australia more than 60,000 years ago, had a wingspan up to 3m wide and powerful talons wide enough to grab a small kangaroo or koala.

It was the largest bird of prey to ever live on the continent, and probably the largest continental eagle globally, according to new research from Flinders University. 

Closely related to Old World vultures of Africa and Asia and the critically endangered monkey-eating or Philippine Eagle, the Flinders palaeontology researchers say the now extinct raptor with a mighty wingspan and powerful talons was the top avian predator in the late Pleistocene.

Yet it has taken decades for it to be officially ‘discovered’ and described in the latest Journal of Ornithology.  

The Flinders University fossil hunters pieced together its story, naming the giant bird Dynatoaetus gaffae (Gaff’s powerful eagle), after extensive new research of fossil cave remains in South Australia’s Mairs Cave in the Flinders Ranges connected the dots to other bones previously found in the Naracoorte Caves, Wellington Caves and near Cooper Creek in the Lake Eyre Basin.  

Flinders University palaeontology researcher Dr Ellen Mather organised a field trip to the Flinders Ranges in late 2021 to revisit the location of four large fossil bones collected by cavers back in 1956 and 1969

“After half a century, and several delays caused by the pandemic, the expedition with volunteers from the University’s Speleological Society found a further 28 bones scattered about deep among the boulders at the site indicated by one of these museum relics.   

“We were very excited to find many more bones from much of the skeleton to create a better picture and description of these magnificent long-lost giant extinct birds,” says Dr Mather, who collaborated with experienced palaeo-ornithologist Associate Professor Trevor Worthy on the expedition.

“It’s often been noted how few large land predators Australia had back then, so Dynatoaetus helps fill that gap.”

Dynatoaetus and the recently described Cryptogyps are new genera of raptors unique to Australia, respectively eagle- and vulture-like, that existed until around 50 thousand years ago, Dr Mather says.

“This discovery reveals that this incredible family of birds was once much more diverse in Australia, and that raptors were also impacted by the mass extinction that wiped out most of Australia’s megafauna.”

“It was ‘humongous’ – larger than any other eagle from other continents, and almost as large as the world’s largest eagles once found on the islands of New Zealand and Cuba, including the whopping extinct 13kg Haast’s eagle of New Zealand,” says New Zealander Associate Professor Worthy, who has excavated several Haast’s eagle skeletons in NZ caves during more than 30 years of research experience in NZ, Australia and the Pacific.

“It had giant talons, spreading up to 30cm, which easily would have been able to dispatch a juvenile giant kangaroo, large flightless bird or other species of lost megafauna from that era, including the young of the world’s largest marsupial Diprotodon and the giant goanna Varanus priscus.”

It also coexisted with still living species such as the Wedge-tailed Eagle, which has interesting implications.

“Given that the Australian birds of prey used to be more diverse, it could mean that the Wedge-tailed Eagle in the past was more limited in where it lived and what it ate,” says Dr Mather. “Otherwise, it would have been directly competing against the giant Dynatoaetus for those resources.”

The latest discovery was made by piecing together the newly unearthed fossils with historic remains in collections of the South Australian Museum and Australian Museum found at locations spanning from the Lake Eyre Basin in central Australia to the Wellington Cave complex in central New South Wales. 

Led by location information on a SA Museum card recording where the earlier specimens were found, the Flinders expedition knew where to look in Mairs Cave in the southern Flinders Ranges. Repeating the measurements made 60 years previously, the cavers descended into a rockpile soon located the fossil eagle bones in crevices.

Thanks to this “serendipitous osteological sleuthing”, additional museum fossils of this species found across Australia soon confirmed the size and other details of the bird, which has been named in honour of Victorian palaeontologist Priscilla Gaff who first described some of these fossils in her 2002 Master of Science thesis.

The article – A giant raptor (Aves: Accipitridae) from the Pleistocene of southern Australia (2023) by Ellen K Mather, Michael SY Lee (SA Museum / Flinders), Aaron B Camens and Trevor H Worthy – has been published in the Journal of Ornithology DOI: 10.1007/s10336-023-02055-x

Also see The Conversation: ‘Australia’s extinct giant eagle was big enough to snatch koalas from trees’