A team of paleontologists has discovered in Australia the remains of a new fossil species of bird that lived during the late Oligocene. Named Archaehierax sylvestris , this species is one of the oldest eagle-shaped birds of prey in the world. ” This is the largest known eagle in Australia for this period of time, ” explains Ellen Mather, a researcher at Flinders University and first author of this work published in the journal Historical Biology .
“Eagles are at the top of the food chain, so they weren’t very abundant, and that’s why they are rarely preserved as fossils,” explains co-author Trevor Worthy. “It is rare, even, to find a bone from a fossil eagle. Getting most of the skeleton unearthed is quite exciting, especially considering the age of the remains. “
The Australian environment during the Oligocene was very different from today. The remains of Archaehierax were found on the arid shore of a dry lake (known as Pinpa Lake) in a desolate sandy desert habitat during ongoing research at Flinders University on an ancient ecosystem from the time when the interior of Australia was covered in green trees and forests.
Hunt among the trees
How did this oversized eagle avoid collisions with trees while hunting? Fossil bones reveal that Archaehierax’s wings were short for their size, much like those of eagle species that live in forests today. Instead, its legs were relatively long and would have given it considerable reach, ”explains Mather. “ The combination of these traits suggests that Archaehierax was an agile flier but not very fast, and would hunt by ambushing its prey . It was one of the main land predators of the late Oligocene, and it pounced on birds and mammals that lived at that time ”.
Archaehierax would have hunted koalas, opossums and other animals in the trees that surround a vast shallow lake, which was abundant with waterfowl, cormorants and flamingos. Of all the known species at this site, Archaehierax is one of the best preserved; the partial fossil skeleton is made up of 63 bones.
“The integrity of the Archaehierax skeleton allowed us to determine where it fits in the eagle’s family tree. It displays a variety of different characteristics than those seen among modern hawks and eagles, ”explains Mather.
“We discovered that Archaehierax did not belong to any of the living genera or families. It seems to have been its own unique branch of the eagle family, ”he muses. “It is unlikely that it is a direct ancestor of any species alive today.”