Prehistoric Eagle Fossil Discovered in South Australia; Experts Investigate Their Survival During the Megafaunal Extinction Event

Thousands of years ago, a species of eagle twice the size of a modern-day apex predator soared over the Australian skies.

Giant Raptor from the Pleistocene Era

In 2021, experts discovered 28 bones of a giant bird of prey in Flinders Ranges, South Australia. These were additional fossils from the initial remains collected from the same site in 1956 and 1969.

In the study "A giant raptor (Aves: Accipitridae) from the Pleistocene of southern Australia," the researchers noted that the fossils belong to an eagle that has a wingspan of up to 10 feet (3 meters) and powerful talons that are wide enough to grab a koala or a small kangaroo. Named Dynatoaetus pachyosteus, the newly-described eagle species lived during the Pleistocene period over 50,000 years ago.

In terms of size, the raptor was similar to the extinct Australian vulture (Cryptogyps lacertosus) and the living wedge-tailed eagle (Aquila audax). It also had stout wing bones and very giant, robust leg bones, indicating that it was even more powerful and heavily built than Aquila Audax, the country's largest living eagle of prey.

The Dynatoaetus genus was endemic to Australia, meaning it cannot be found anywhere else. However, paleontologist, Dr. Ellen Mather from Flinders University reported that their analyses revealed that Dynatoaetus pachyosteus may be related to the Philippine eagle (Pithecophaga jeffreryi) and the large crested serpent eagle (Spilornis cheela).

Dynatoaetus pachyosteus was the second species found under this genus, the other being Dynatoaetus gaffae. Both species were found in Victoria Fossil Cave deposit, suggesting they lived in the area between 500,000 and 200,000 years ago. Since eagle fossils are rare, it is unknown when these birds went extinct.

The discovery of Dynatoaetus pachyosteus confirmed that its genus is not closely related to any eagles outside Australia. This suggests that this raptor group must have been in the country for quite some time instead of being a relatively recent arrival.

Surviving Mass Extinction

The mass extinction of Australian megafauna is usually related to the demise of large mammals, like the giant short-faced kangaroo, the marsupial lion, and the giant wombat. The event also included the loss of large reptiles, such as the giant armored skink, the constricting snake, and the giant goanna.

However, other groups, such as the birds of prey, were also affected which went extinct worldwide during the Late Pleistocene. It was believed that the loss of large mammalian species affected the food supply of the scavengers.

The two giant eagles were likely too specialized as hunters and scavengers of megafauna to adapt to a rapidly changing environment. As a result, their extinction caused a further chain of effects throughout the ecosystem.

Whatever caused the extinction of the two eagle species resulted in Australia having only one large raptor in its modern inland fauna. This is unusual since most continents at present have several eagles and vultures.