First proof of old birds hirking over the Arctic circle

Recently discovered bone fragments from Alaska suggest that birds have bred and wiped in the Arctic for at least 73 million years.

“Which is a bit crazy because it is not easy to live in the Arctic and have newborn babies up there,” says student author Lauren Wilson at Princeton University.

Today, about 250 bird species have adapted to thrive on the Earth’s poles. Some migrate great distances and spend only the summers there, with 24 hours of light every day. Others also remain over the winter, persistent released temp that and eternal darkness for weeks afterwards. But a lot of Littletle was known about how and when these birds first came to the highest latitudes on earth.

Wilson and her colleagues searched for traces of old birds in a number of cliffs known as Prince Creek formation in northern Alaska, which was shaped on a coastal flood about 73 million years ago. At that time, what is now Northern Alaska, approx. 1000 to 1600 kilometers closer to the North Pole than it is today.

The team restored chunks of old soil from some thin rock layers in the formation. This was in winter when temperatures we -30 ° C (-22 ° F) and home was a tent. “It’s definitely the most intense fieldwork I have Eva,” says Wilson.

Back in the laboratory “spent the hours staring” through a microscope “by grain of sediment less than two millimeters,” Wilson says, carefully hunting through them after small fragments of fossil bones.

They revealed more than 50 old bird fossil fragments, many of which came from chickens or even embryonic birds. The fossilized bones from such young birds have an fungal structure because they take up an internship when bones grow rapidly.

While birds probably began to witch in the Arctic even earlier than 73 million years ago, the fossils are the oldest traces of this behavior that is so far. They push back to this in birds with 30 million years back.

Still, the fossils are very fragmented. They also show that you show where the birds lived there year -round or just during the warmer summers.

“The Arctic, as we know it, Espetius the foods that emanate an existence in the cold and darkness could not exist without Mayry Brirds calling the high latitudes home,” says Steve Brutted at the University of Edinburgh, UK, involved in the study. “These fossils show that birds were already integrated parts of these high -width communities many years ago.”

Wilson’s team could identify three main groups of birds among the fossil fragments: turned off toothed birds similar to pockets, extinct toothed birds that look like gulls, and some species that can belong to the same group as all modern birds.

However, the samples did not have any bones from a group of more archaic birds known as the enantiornithins – or “opposite birds” – which dominate fossil records from that time everywhere in the rest of the world. Gerald Mayr at the Senckenberg Research Institute in Germany, who was also involved in the study, believes this is “meaning” that might suggest that the ancestors of more advanced birds could cope with harsh Arctic conditions of some unique evolutionary traits that the birds of the ancestors were missing.

The ecosystem that gave rise to the Prince Creek formation exists at the time when the big non -birdinosaur were still controlling the world, and fossils suggest that the ancient birds shared these Arctic ecosystems with species of tyrannosaur and horned ceratopsians. There is this evidence that of these dinosaur also embedded in the Arctic.