Likely the largest eagle in the world, identifying the fossils of the Dynatoaetus gaffae took a decade of work.
A massive bird of prey soared over southern Australia about 60,000 years ago.
According to the researchers at Flinders University who led this study, it was the largest eagle to ever live on the continent and likely the largest of all eagles worldwide.
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| The Dynatoaetus gaffae coexisted with still living species such as the Wedge-tailed Eagle (above). Andrew Haysom/iStock |
Dynatoaetus gaffae had a wingspan of up to 9.8-foot (three meters) wide and powerful talons capable of grabbing a small kangaroo or koala.
Discovery of the fossil
However, identifying this species took a decade of work. In 1956 and 1969, four large bones were discovered in South Australia's Mairs Cave in the Flinders Ranges.
Later in 2021, Dr. Ellen Mather and her team went on a field trip to the Flinders Ranges to look for any missing clues. An additional 28 bones were discovered scattered, deep among the boulders at the site by the team.
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| Flinders University fossil hunters descend the 17m drop at the entrance to Mairs Cave in the Flinders Ranges. |
They also linked the dots to the bones discovered at other locations, including Naracoorte Caves, Wellington Caves, and near Cooper Creek in the Lake Eyre Basin.
This helped the fossil hunters piece together the story of this massive bird. The findings were published in the Journal of Ornithology.
According to the study, this extinct raptor was a top avian predator during the late Pleistocene. This era was when giant megafauna like the mammoth lived on the planet.
“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,” said associate professor Worthy, in a statement.
The other closely related species
It was as large as Haast's eagle, the largest ever discovered, according to the team. “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,” said Worthy, who has studied several Haast’s eagle skeletons in NZ caves.
This now-extinct species is found to be closely related to Pleistocene-era Old World vultures from Africa and Asia. It is also thought to be the closest cousin of the monkey-eating, Philippine Eagle. The colossal species then coexisted with the Wedge-tailed Eagle, which now lives in Australia.
The authors believe it went extinct as its preferred prey became scarce. Eventually, Australia's giant eagles and vultures, as well as another megafauna, became extinct around 50,000 years ago.
The researchers hope to find more fossils of this mighty predator and fill in the evolutionary gaps of eagles.
“It’s often been noted how few large land predators Australia had back then, so Dynatoaetus helps fill that gap. “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,” said Dr. Mather.
Study abstract:
The giant accipitrid Dynatoaetus gaffae gen. et sp. nov. is described from existing and newly collected material. Initial fossil remains were collected from Mairs Cave (Flinders Ranges, South Australia) in 1956 and 1969, and comprised a sternum, distal humerus and two ungual phalanges. A further 28 bones from this individual—including the neurocranium, vertebrae, furculum, and additional wing and leg bones, most of which were incomplete—were discovered at the site in 2021. This allowed identification of additional fossils from the same species in collections from Cooper Creek (Lake Eyre Basin, SA), Victoria Fossil Cave (Naracoorte, SA) and Wellington Caves (Wellington, NSW). Dynatoaetus has variable similarity across elements to those of living species in the Perninae, Gypaetinae, Circaetinae and Aegypiinae.
Parsimony and Bayesian phylogenetic analyses of combined morphological and DNA data resolved it as the immediate sister-group to the Aegypiinae within the Circaetinae + Aegypiinae clade. The robust and eagle-like morphology of the lower hindlimbs suggest that the species was a predator, rather than a scavenger, and thus functionally similar to large circaetines such as the Philippine Eagle Pithecophaga jefferyi. Furthermore, this new species is the largest known bird of prey from Australia, much larger than the modern Wedge-Tailed Eagle Aquila audax. It is outsized in Australasia only by female Hieraaetus moorei (the extinct Haast’s Eagle from New Zealand). It is inferred to have been Australia’s top terrestrial avian predator during the Pleistocene, ranging from arid inland Australia to the more temperate coast, and likely became extinct around the time of the megafaunal mass extinction which peaked around 50 Ka. Its extinction in the late Pleistocene, along with the recently described scavenging vulture Cryptogyps lacertosus, marked a distinct decline in the diversity and function of Australia’s raptor guild.