25 million years ago, new research suggests that an eagle with a half-foot-long talon robbed an ancient koala from an Australian tree.
Paleontologists have discovered 63 fossilized bones since ancient times Koala-Hunter during an expedition to Lake Pinpa, a salt lake east of the Flinders Mountains in South Australia, in 2016.After a thorough examination of the bones, the team recently named a newly discovered eagle seed. Archaehierax sylvestris. They determined that ancient birds of prey do not have direct offspring that are alive today.
Bones date back to the Oligocene era, which lasted from 33.9 million to 23 million years ago. A. Silvestris Specimens are the oldest fossil eagle ever found in Australia and one of the best preserved, scientists reported in a journal on September 27. Historical biology..
“As apex predators, eagle and hawk are less abundant than the species they prey on,” Ellen Mother, a PhD student at Flinders University in Adelaide, Australia, emailed Live Science. Told. “This tends to be carried over to fossil records, as individuals of these species are less likely to fossilize.”
And when they are discovered, eagle fossils often contain very few bones, or sometimes only one, creating newly discovered fossils with 63 bones.
Today, fossilized Lake Pingpa rarely retains water and is set in a landscape of dunes sparsely adorned with grass and trees.But back A. Silvestris Soaring up in the sky, the lake looked significantly different, vertebrate paleo-vertebrate zoologist and senior author Trevor Worthy, an associate professor at Flinders University, told Live Science in an email.
At that time, the excavation site for Lake Pingpa was on a larger lake, the shore of the lake’s water system, extending the temperate zone by about 62 miles (100 km). Rainforest..According to fossil records, fish crocodile The lake was inhabited by freshwater dolphins, with stag beetles, possums, and ancestral koalas hanging on the shore.
“Overall, Lake Pinpa is the richest fossil site of the time in South Australia,” Worthy said. The earliest known ancestors of modern marsupials such as Bandicoot, Possum, Kangaroo and Wombat are all found here, along with many avian herbivores such as ducks and cormorants. But even in this ancient Australian fossil treasure trove, he said, there were few specimens of hawks and eagles, in between.
When Worthy’s team first discovered A. Silvestris A 2016 fossil said, “I quickly realized that there were big birds, but they were so fragmented that they weren’t brilliant.” In the first bone fragments they unearthed, the team found a bone in the lower leg called the fusion of the nail and metatarsal bone. These bones revealed that the specimen was an eagle, but at that time they did not know which species. So they carefully scooped the bone into a large mass of sediment, wrapped it in plaster, and sent the specimen back to their laboratory.
Worthy and the team then carefully released the bone fragments one at a time from the surrounding deposits and put all the bone fragments together into a complete bone with a jigsaw. Some bones contained as many as 20 small pieces, Worthy said. Next, we compared the assembled bones with the bones of various falcons, ospreys, eagles, and hawks. Based on this analysis, she determined that the fossils belonged to a family of birds of prey called the Accipitridae, including hawks, eagles, kites, and Old World vultures.
However, certain newly discovered fossil features, such as toe spacing and leg muscle insertion points, set birds apart from other members of the Accipitridae family, Mother said. Stated. Based on these characteristics and the age of the ruins of Lake Pingpa, the team concluded that the birds belong to previously unknown subfamilies and eagle species.
“We can be confident that the fossil represents a new species as the only other eagle species of the same age, Pengana Robert Boresi The form of Riversley, Queensland, Archaehierax“Mother said.
Unique features of A. Silvestris Bones also hinted at ancient bird hunting styles. The eagle had a 5.9 inch long (15 cm) leg span and long legs compared to its overall size. In short, predators had the best tools to reach and steal large prey from the top of the tree. And the relatively short wings of the eagle are not particularly fast flying, A. Silvestris It may be good at bombing unprotected koalas from above.
Eagle fossils are generally hard to come by, but they are relatively common at certain excavation sites, Mother said. For example, at the La Brea Tar Pits in Los Angeles, eagles and other predators were trapped in tar while trying to eat other animals in the pit. This means that a significant number of predator fossils can be found there today.
“But this is not the case for Lake Pingpa,” Mother said, saying that certain characteristics of the environment do not favor the protection of predators. “Our eagle fossil was a matter of luck.”
Originally published in Live Science.
Koala hunting eagle terrorized Australia 25 million years ago
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