Scientists discovered a 25-million-year-old fossil that belongs to one of the largest eagles, which has been unearthed in South Australia. This species once preyed on koalas, possums, and other marsupials.
The research was published Monday, Sept. 27, in the peer-reviewed journal Historical Biology; the newly discovered species, Archaehierax sylvestris, is one of the world’s oldest eagle-like raptors, as Independent reported.
“This species was slightly smaller and leaner than the wedge-tailed eagle, but it’s the largest eagle known from this time period in Australia,” Ellen Mather, the study’s first author and a Ph.D. candidate at Flinders University, said in a statement.
“The foot span was nearly 15 cm 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,” Ms. Mather added.
In March 2016, during a research trip to Lake Pinpa in South Australia, researchers from Flinders University in Adelaide discovered dozens of bone fragments in a dry lake. At this site, the team also found a partial raptor skeleton consisting of 63 bones.
According to the study, Archaehierax is the largest eagle known to have lived in Australia during the Oligocene period, dating back about 33.9 million to 23 million years ago.
“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,” Trevor Worthy, co-author and associate professor from Flinders University, said.
The findings show that the ancient raptors lived in the Oligocene period when Australia’s interior was covered with trees and lush green forests—not the dry outback of today.
“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,” stated Mather.
“The combination of these traits suggests 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,” she added.
When scientists tried to figure out where the new species fit into the eagle family tree, they discovered several features that are not prevalent in 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,” Mather said. “It’s unlikely to be a direct ancestor to any species alive today.”