The parched deserts of the South Australian outback were once a rainforest filled with a rich variety of birds and animals. Now, thanks to a new fossil discovery, we know the apex predator

of this lush ecosystem was a newly discovered eagle that lived 25 million years ago. We discovered the fossil remains of this species, named _Archaehierax sylvestris_, in prehistoric

sediments at Lake Pinpa, 400 kilometres north of Adelaide. The fossil, unearthed in March 2016, is described in a newly published paper in the journal Historical Biology. It is one of the

most complete raptor fossils from this time period found anywhere in the world. It comprises 63 bones, which is truly exceptional; most fossil birds are named on the basis of just a single

its relatively short wings and long legs, this eagle was likely an ambush hunter, waiting for unwary prey to approach, rather than a soaring forager. In the forest, it probably preyed on

medium-sized marsupials. But from a high perch, it would also have made forays over the lake where it could catch ducks and flamingos. ------------------------- _ READ MORE: ANCIENT BILBY

AND BANDICOOT FOSSILS SHED LIGHT ON THE MYSTERY OF MARSUPIAL EVOLUTION _ ------------------------- FOSSIL TREASURE TROVE Since the 1970s, the barren, salt-crusted sediments in South

Australia’s arid north have yielded a range of bone fragments, teeth, and other fossils of the animals that lived there — many of which would have been prey for _Archaehierax_. These fossils

include a host of mammals, ranging from wombat ancestors the size of a small cow, through a range of tree-dwelling herbivores such as possums and koalas, to small terrestrial carnivores no

bigger than a mouse. These animals lived around a large lake where crocodiles and turtles abounded, and freshwater dolphins played. Waterbirds were abundant, including cormorants, several

types of flamingo, four species of duck, and _Presbyornis_, a bizarre long-legged fowl that went extinct elsewhere in the world 20 million years earlier. Many smaller forest birds such as

songbirds, parrots and rails are also known, but most are not yet described. GLOBAL EAGLE FAMILY _Archaehierax_ was clearly a member of the raptor family, which includes most hawks and

eagles. But its bones differed in many ways from all other raptors, including similar-aged ones from elsewhere in the world. _Archaehierax sylvestris_ was not the only raptor we found at

Lake Pinpa. Isolated bones show a smaller eagle also lived in these forests, but the fossils are too fragmentary to give this species a name. There is another fossil raptor known from

deposits at Riversleigh World Heritage Area in northwest Queensland. _Pengana robertbolesi_ is a few million years younger than _Archaehierax_, and not closely related to the Pinpa bird. It

was adapted to capture prey in holes in trees. Our analysis suggests _Archaehierax_ was probably not closely related to any living raptor. Rather, it represented an ancient lineage that

split off near the base of the raptor family tree. This is consistent with previous genetic analysis suggesting most living groups of hawks and eagles evolved only in the past 20 million

years — roughly 5 million years after _Archaehierax_ lived and died. Previously, raptor fossils as ancient as 25 million years old were only known from Europe and North America.

_Archaehierax sylvestris_ and its smaller contemporary show that Australia was an important geographic location in the early global evolution of raptors. Australia is already widely

understood to be a cradle of evolution of songbirds, and our island continent doubtless played a similar role in the evolution of other types of birds too. ------------------------- _ READ

MORE: MEET THE GIANT WOMBAT RELATIVE THAT SCRATCHED OUT A LIVING IN AUSTRALIA 25 MILLION YEARS AGO _ ------------------------- These raptors and the earliest songbirds lived in temperate

rainforests. Back then, the area around what is now Lake Pinpa was located more than 1,100km south of where Adelaide is today, at a latitude equivalent to present-day Fiordland at the

southwestern tip of New Zealand. In the 25 million years since, continental drift has carried Australia and the fossils north at 6 centimetres per year (the speed at which your fingernails

grow), travelling more than 1,500km. The rainforest where these birds lived is now the arid outback. And there are almost certainly many fossils awaiting discovery there that will tell us

more about how Australia’s unique birds evolved.