Eagle with a 6-inch foot span roamed Australia 25 million years ago

Ian Randall For Mailonline 

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An eagle with a six-inch foot-span that ambushed unsuspecting prey such as flamingos and koalas ruled the food chain of South Australia 25 million years ago.

This is the conclusion of Flinders University experts who identified the new species, Archaehierax sylvestris, based on a 63-bone fossil discovered near Lake Pinpa.

Found on a remote cattle station, the remains from the late Oligocene Period are one of the oldest-known and 'best preserved' eagle-like raptors in the fossil record.







ARCHAEHIERAX'S AUSTRALIA

During the late Oligocene when Archaehierax sylvestris lived, the environment in Australia was starkly different to how it appears today.

While Lake Pinpa is today a bone-dry desert, 25 million years it was a vast, shallow body of water surrounded by verdant forests.

The team believe that Archaehierax would have ambushed its prey — likely koalas, possums, waterfowl, cormorants and flamingos — by swooping down from these trees and grabbing them with its long legs.

'This species was slightly smaller and leaner than the wedge-tailed eagle [Australia's biggest eagle alive today], but it’s the largest eagle known from this time period in Australia,' said paper author and palaeontologist Ellen Mather of Adelaide's Flinders University.

'The foot span was nearly 15 cm [6 inches] long, which would have allowed it to grasp large prey. The largest marsupial predators at the time were about the size of a small dog or large cat, so Archaehierax was certainly ruling the roost.'

'The fossil bones reveal that the wings of Archaehierax were short for its size, much like species of forest-dwelling eagles today. Its legs, in contrast, were relatively long and would have given it considerable reach.

'The combination of these traits suggest Archaehierax was an agile but not particularly fast flier — and was most likely an ambush hunter.

'It was one of the top terrestrial predators of the late Oligocene, swooping upon birds and mammals that lived at the time.'

'With eagles at the top of the food chain, they are always few in number — and so are infrequently preserved as fossils,' added co-author and fellow Flinders University palaeontologist Trevor Worthy.

'It’s rare to find even one bone from a fossil eagle. To have most of the skeleton is pretty exciting, especially considering how old it is.'

'I have studied this [site] for many years now, and this is the most exquisite fossil we have found to date,' Professor Worthy added.




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'The completeness of the Archaehierax skeleton allowed us to determine where it fits on the eagle family tree,' added Ms Mather.

'It shows a range of features unlike any seen among modern hawks and eagles.

'We found that Archaehierax didn’t belong to any of the living genera or families. It seems to have been its own unique branch of the eagle family.

'It’s unlikely to be a direct ancestor to any species alive today,' she concluded.

The full findings of the study were published in the journal Historical Biology.