With a wingspan of up to about three meters, it far eclipsed what is now Australia's largest bird of prey: Using newly discovered fossils, researchers describe the extinct bird of prey Dynatoaetus gaffae - one of the largest known representatives of the group of eagles. Up until about 50,000 years ago, Dynatoaetus apparently killed quite large prey in Australia with its huge claws. In the course of the wave of extinctions in the local fauna, however, the majestic bird of prey also disappeared from the sky of the continent at the end of the Pleistocene.
The story of its discovery is as exciting as the giant eagle itself. It began with an expedition into the depths of South Australia's Mairs Cave in 1959. In one chamber, cavers found deposits containing the bones of various animal species. Among these fossils were isolated remains of a bird that may have been a large eagle. A second expedition in 1969 then delivered more fossil puzzle pieces. For about half a century, however, this thin level of knowledge remained and the identity of the bird remained unclear.
Fossils from a cave expedition
But in 2021, a team led by the paleontologist Ellen Mather from Flinders University in Adelaide decided to get to the bottom of the mysterious finds again: They descended again into the depths of the cave to the site - in the hope of finding more bones of the to find the mysterious bird.
The exciting action was a success: "Half a century later, many more bones were discovered that were scattered deep under the rocks at the site," reports Mather. Among other things, the cavers recovered a partial skeleton of the bird - including leg and wing bones and a skull. Thanks to these discoveries, scientists have now been able to describe the spectacular bird of prey as a new species.
The bird of prey named Dynatoaetus gaffae had enormous dimensions and the characteristics of a predator instead of a scavenger. It was almost twice the size of Australia's largest bird of prey today - the wedge-tailed eagle (Aquila audax). According to estimates, Dynatoaetus gaffae probably reached a wingspan of about three meters. He was thus the largest known mainland representative of the eagle. It was apparently only slightly surpassed by two "island species": "It was gigantic - bigger than any other eagle from other continents and almost as big as the largest known eagles that once lived on the islands of New Zealand and Cuba," says senior author Trevor Worthy .
Mighty claws for big prey
But who was the unusually large bird of prey after? “It had huge claws, up to a foot in diameter, with which it could easily have taken down a young kangaroo, a large flightless bird, or any of Australia's extinct megafauna of the time. These include the young of the largest marsupial, Diprotodon, and the giant monitor Varanus priscus,” says Mather. 'It has often been noted how few large carnivores there were in Australia at the time, and Dynatoaetus is now helping to fill that gap,' the researcher says.
Interestingly, at that time Dynatoaetus apparently coexisted with the wedge-tailed eagle that survives today. Presumably, these species were specialized on different prey animals. This may have been a reason why the large, unlike the small, eagle has not survived to this day. Dynatoaetus disappeared at the same time as many larger Australian animal species became extinct around 50,000 years ago. Perhaps some of them were among its important prey items. It may not have adapted sufficiently to hunt others, and this may have been the end of Australia's largest bird of prey.
Source: Flinders University, professional article: Journal of Ornithology, doi: 10.1007/s10336-023-02055-x